home      FAQs

Glossary of Packet Networking Terms

Important! This glossary has evolved over decades. Some of the definitions within would seem to advocate unreasonable system designs and archaic software which may be counter-indicated by modern design practices. Do not take any of the statements and definitions in this glossary to indicate advocacy or even tolerance of projects, products, ideas, or theories described hear-in. Thanks.

ACKnowledgement. A packet sent by a receiving station to tell the sending station that the packet was received correctly and the sequence number of the next packet that it would expect. The sending station then knows whether to send the next packet or to resend a missing packet. A form of handshaking. Also the 1 character handshaking response used in AMTOR mode A (ARQ mode).

See ACK.

Advanced Electronics Applications Inc. AEA designs, manufactures and markets a wide range of amateur packet products as well as other amateur related items.

Audio Frequency Shift Keying: A method of digital modulation. This is a mechanism for sending digital information over an audio line. AFSK is used over telephone lines and over radio. A signal 0 is sent using a low tone, often 880hz, while a signal 1 is sent using a high tone, often 2200hz. This is the mechanism used in packet radio 1200 baud TNC/modems.

Asynchronous Framing Technique. This is the protocol used by ROSE switches on an RS-232 LAN. First proposed by Toby Nixon of Hayes, it is a pending CCITT adoption as the accepted method for sending X.25 over asynchronous links.

An algorithm is a predetermined step by step procedure that solves a specific problem. This is a term used in computer programming.

An alternate ID for a packet station. Usually an alias is used for user connects to packet stations. Also called a node-name or a mnemonic, the alias will be sent in the TO field of a packet transmission originated at a TNC and directed at a system which can recognize its own alias.
Stations having an alias will always used the legal callsign and ssid for the FROM field. Nodes/switches will automatically translate the alias and will instead use a callsign, when making link level connects to a station having an alias.

Aloha net
An early (1975) packet radio experiment conducted by the University of Hawaii. The Aloha net is known for its performance definitions for packat systems which have hidden transmitters.

Perhaps the best of the personal computers available in the hobbyist price class during the 1980s, the Amiga saw terrible sales and lousy acceptance by the business and hobby computer community. It is most likely because of Commodore's poor marketing and the excellent marketing efforts of Apple, IBM, Microsoft and Digital. The Amiga did not have very high acceptance in the Amateur Radio community either. Users of the Amiga were known to hold their computers in high regard. Many high quality commercial programs were first delivered on the Amiga, including Video Toaster which was used in the TV series Babylon 5 for exterior images and space-flight scenes.

AMateur Packet Radio NETwork. Originally the name for TCP/IP IPv4 networks whose interconnections were performed over Amateur Radio. In the early 80s, still early in Internet history, the class A netblock 44 (also written as 44/8) was granted to the AMPRNet so that if Internet and Amateur Radio TCP/IP ever crossed paths, the routing would be respected.
In the later half of the 1990s the AMPRNet led the charge away from over-the-air packet radio through the most excellent interoperability between TCP/IP packet radio and the Internet.

AMateur radio Research And Development corp. A non-profit group based in Virginia devoted to advancing new radio techniques.

AMtor TEXt. A bulletin broadcasting system used by AMTOR bulletin stations like W1AW. Similar to the US Coast Guard NAVTEX system of naval advisories.

AMateur Teleprinting Over Radio. An improved method of RTTY that uses some forms of error recognition and correction to improve copy. Sort of a very simple basic form of packet using 3 character groups. AMTOR uses a limited character set (Capitol letters, numbers and a couple of controls like CR/LF - similar to the Baudot set). AMTOR is normally used on HF frequencies. AMTOR is modeled on a commercial protocol called SITOR. See also ARQ, FEC, SITOR, PACTOR, RTTY, Baudot.

analog signal
An electrical signal that changes in a smooth continuous manner and whose voltage or current may represent a numerical value or other physical property. Compare with: digital signal which is a signal that changes in discrete unambiguous steps.

American National Standards Institute. A US organization that sets standards on all sorts of things from nuts to computers. See also ISO.

Amtor Packet Link. An AMTOR BBS program written by Vic W5SMM and used on an IBM PC to operate an AMTOR mailbox and gateway between the packet BBS network and international AMTOR links.

Automatic Packet Reporting System. APRS is a shareware program written by Bob, WB4APR to map and track stations and objects as a graphical display. It can automatically map the location of packet stations using information contained in the beacon message or from a interfaced GPS receiver. It can also transfer messages to these stations and is useful during public service events.

Address Resolution Protocol. A TCP/IP protocol that matches proper callsign with TCP/IP address using an automatic broadcast query to a remote station if necessary.

ARPA Suite
The set of protocols standardized by the Advanced Research Projects Agency of the US Dept of Defense. Includes TCP and IP as elements, but leaves the lower levels (subnetwork and down) deliberately unspecified. The ARPA suite can be run on top of multiple subnetworks, unifying them into a single Internet.

Automatic Repeat reQuest. An error correction technique in AMTOR where the receiving station sends a 1 character ACK/NAK response to each AMTOR group sent. See AMTOR, ACK, NAK, FEC, handshaking.

American Standard Code for Information Interchange. Also called USASCII. The standard code that defines text characters (and control characters) in terms of binary or hexidecimal numbers. It is used for the tranfer of text between computing devices or input/output terminals.

Asynchronous Serial Line Protocol (usually just called SLIP). A technique for encoding IP datagrams so they can be sent across ordinary asynchronous modems and communications hardware.

asymmetric link
A link that works well in one direction but not in the other.
If this occurs on a dedicated point‑to‑point link, the throughput will be bad and it might not be clear which direction is bad. If this occurs on a zoo channel where the route qualities between nodes are not carefully set, this can result in very inconsistant behavior depending on where the link is being set up from or to.

A method of serial communication which uses start and stop bits to delimit each character and to synchronize the receiver to the data stream. The time between characters is undefined in async mode. Compare with: synchronous serial communication where a clock signal is either encoded into the data stream in some manner or is provided separately. Synchronous communications does not need start and stop bits. RS-232 is an asynchronous mode of communication.

audit trail
The list of headers (R: lines) attached to every BBS message that is used to trace the path that the message has taken from its originating BBS. See also header, path, R: header, BBS.

Many of the bulletin board and mail server programs (BBS) are capable of passing messages to each other. The process of a bulletin board recognizing that it has mail to go to another bulletin board, connecting to another board and then sending the traffic is called Autoforwarding. This allows packet users to send mail in a non real time fashion anywhere on the planet where compatible BBSs exist. See Forward File.

A process by which a network node can pass traffic to another node via one or more intermediate nodes.

This is the designation for the protocol used by TNCs to talk to one another. A book from the ARRL includes a [cryptic but] complete specification for AX.25. See protocol.

Binary-to-ASCII/ASCII-to-Binary. A file conversion program written by Brian KA2BQE. Also called BTOA or Radix 85. See also R95, 7-Plus.

A backbone is a system of links where nodes may communicate without interfering with or being interfered with by local access, and where data may be passed in a fashion and with hardware that is optimized for passing data, rather than optimized for inexpensive user stations.
Historically, packet radio users operated on the 2meter band. User stations would be on the air or off the air in unscheduled intervals. The configuration of a network station meant to service user stations would take into account that there could be competition for transmit time from the chaotically operated user stations. Generally a user access portal on a network node would have a Persistance and Slot-time setting appropriate for a zoo channel. A backbone station, on the other hand, is optimized to talk to one and only one other station Persistance would be appropriately set to never delay transmission to take advantage of the lack of competition on the channel.
See also Zoo channel, Persistance.

When a packet is sent and not responded to, the sending station will wait a specified "backoff" time before retrying. DWAIT and Persistance are two techniques of backoff. See FRACK, DWAIT, Persistance, collision avoidance.

back-up battery
A lithium cell used in TNCs and other computing devices to maintain the data stored in the RAM during times when the device is powered off. See also RAM, EPROM.

The original data signal before any encoding or modulation operations are performed on it is called the digital baseband signal.

The "signaling" rate on a data channel expressed as signal elements or symbols transmitted per second. A signal element or symbol may be a pulse or a burst of tone or any discrete signal change that can be measured. Another description of a signaling element would be a time-sliced bit of carrier modulated with data. For example: in 1200 baud packet, one signaling element would be a 1/1200 of a second of carrier (either rf carrier in the case of FSK or audio tone carrier in the case of AFSK) that would be frequency shift modulated by the data. A non- electrical analogy for a signaling element might be the flags that a ship flies to communicate with other ships important information. The flag would be the signaling element and one flag could communicate any one of hundreds of "data" messages. Another analog would be the semaphore signaling system used by Boy Scouts in which the visual picture of the person holding the flags is the signaling element and the position of the flags denotes the data (letters and numbers) being encoded. A signal bit or symbol may contain more than 1 data bit so therefore baud is not equal to bps. A telephone 9600 bps modem usually operates at 2400 baud with 4 bits of data (16 possible data states) in each signaling element. See also bps, data rate, transfer rate.

A 5 bit code used on RTTY communications. Named after J. Baudot, an early french inventor of telegraphic instruments. Compare with: ASCII which is an 8 bit code capable of coding 256 characters instead of 32 for baudot. See also ASCII, RTTY, AMTOR.

A simple modem and software package designed and supported by DL8MBT, DG3RBU and the baycom group in Germany. Early versions were shareware but the latest version (v1.5) is a commercial product marketed in North America by PacComm and Tigertronics.

A Baycom modem marketed by Tigertronics Inc.

Bulletin Board System. A server packet station which sends, receives and distributes bulletins and private messages for the benefit of packet users. It may also provide access to a library of data files of useful information for users. See also CBBS,FBB BBS, home BBS, MBL BBS, MSYS, PMS, REBBS, RLIBBS.

A regular broadcast of a UI (Unnumbered Information) frame from a packet station for identification purposes or as an information broadcast (such as a Mail-For broadcast from a BBS).

Bit Error Rate. The average number of errors per given quantity of data bits transmitted on a communications system. Usually expressed as errors per thousand or million or some such figure.

Bit Error Rate Test. Any error test on a communications system or component (such as a modem) to determine the average rate of occurance of errors in the data stream being passed. See also BER.

beta test
Beta test is the pre-release testing of hardware or software with selected typical customers to find out if there are any bugs or problems before releasing it to the general public.

Bulletin ID. A number given to each bulletin sent out in the BBS forwarding system for identification purposes and to prevent duplicates being created in the system. Compare with: MID which is a number given to all messages on the BBS system, personal as well as bulletins. The MID and the BID of a bulletin may be the same. Personal messages do not have BIDs unless they are addressed to a distribution list like SYSOP.

The smallest possible unit of data. A 0 or 1 number in the binary number system. Any one position in a multibit binary number.

bit bucket
Slang for a data "Garbage can". Sending a message to the bit bucket means to erase all trace of the message.

A technique used to prevent confusion between any 111111 bit pattern in the data and the flag character (01111110) used to delimit the start and end of each frame in the packet.

block check character
In a technique used to check transmission accuracy, a block check character is a character transmitted by the sender after each message block and compared with a similar block check character computed by the receiver. See also checksum, CRC, FCS.

A node or packet switch software written by John G8BPQ that creates a multiport node on an IBM PC or clone. Very popular with BBS operators to provide multiconnect BBS services with several ports i.e. LAN and Backbone ports.

Bits per second. The rate at which binary data is transferred on a circuit. See also baud, data rate, transfer rate. Compare with: baud, the "signaling" rate on the data channel.

A bridge is a server that links between two different frequencies but using the same protocol. Compare with: Gateway, which links two different networks using different protocols.

A communications protocol for sending binary files over packet radio. It is somewhat less efficient that other programs of this type and therefore is not recommended. See also 7-Plus, R95, B2A/A2B, conversion program.

See B2A/A2B.

By The Way. An abbreviation sometimes seen in packet messages.

An 8 bit binary number (0 to 255) usually written as two hexidecimal numbers such as 1E (decimal 30) or AF (decimal 175). All modern computers handle data as bytes.

callbook server
A server whose function is to allow stations to access callbook information either on-line or by remote file request.

capture effect
In FM frequency modulation operation, if two signals (or more) are impinging onto a receiver at a time, the FM receiver may be able to demodulate the strongest signal.
Depending on the relative intensity of the signals, as well as bandwidth and channel noise conditions, this capture effect can be somewhat profound. It can be demonstrated on an FM repeater by generating a modulated FM signal from a weaker station into the repeater, and then a stronger station keys up and sends a non modulated signal. All trace of the weaker signal is eliminated at the receiver. Depending on conditions, the signal strength of the stronger station may be only slightly higher than the weaker station. Both may be fully quieting. This experiment you may try at home.

CAT5 cable
Category 5 cable. CAT5 refers to a telephone specification for an 8 conductor cable used for telephone, Ethernet, and other purposes. For the purposes of packet radio, we're probably not all that interested in the difference between the different categories. It does matter for some things that are really nearby packet radio networking.

The interesting thing about Ethernet cable is that it uses solid core wire and has 4 twisted pairs of wire in a jacket.


A packet BBS system originally written in C programming language by Hank, WRLI as a "generic" BBS code and released to the public domain in 1986. Other authors and groups then extended and supported various versions of the code. Best known is the DOS version written and supported by Ed, K3RLI and others of the CBBS Group. An Amiga version was produced and supported by Peter, VE5VA and Dave, VE3GYQ produced a LINUX version. Versions for ATARI ST and VMS may also be available.

Consultative Committee for International Radio. An international organization that sets standards for radio communication.

Consultative Committee for International Telephony and Telegraphy. A United Nations committee for telecommunications standards.

Broken up into small areas, or cells. Cellular techniques used in radio communications allow many users to access a network and allow the reuse of frequencies in a more efficient manner. Cells are created by limiting the power transmitted and by the use of specially designed antennas and receivers.

cellular LAN
A packet LAN node (user node) that has a deliberately limited coverage such that it serves only the number of users it can handle efficiently. Some suggest that a cellular LAN should cover a population of 100,000 people with 100-200 amateurs and 50 packet users. The frequencies used could be repeated within short distances so long as the coverage areas do not overlap. The cellular user nodes would be linked together with backbone links to form a network allowing any user to reach any node in the network.

Any letter, number, punctuation or any other symbol including control characters, contained in a message.

chat node
See conference node.

A number used for error checking purposes. It is the arithmetic total of all data bytes in a data block. See also FCS (frame Check Sequence), block check character.

When a computer is unable to process data as fast as another computer is sending it, the receiving computer may instruct the sending computer to stop sending the data. This condition is often referred to in the packet world as "choke". "Unchoke" refers to the re-enabling of the sending computer. A computer in this case is the node or TNC.

In a TheNET network, a circuit is an assigned connection between two nodes.

Connectionless Network Service (see connectionless, datagram).

An improved technique for packet communications on HF frequencies. Clover uses 4 audio data channels (like a four-leafed clover) and automatically adapts to changing propagation conditions. It uses a form of forward error correction (FEC) to improve efficiency. See also FEC, AMTOR, PACTOR.

See PacketCluster, node stack.

Complementary Metal Oxide Semiconductor. A type of digital circuit made up of MOSFET transistors widely used in computers and other digital devices. CMOS circuitry generally uses very low power and can operate over a wide voltage range (typ 3-15v). Some versions are compatable with TTL circuitry. CMOS is also the name given to the memory that stores set-up configuration information in an IBM AT computer. See also TTL.

Where 2 stations transmit a packet on the same channel during the same time period causing interference and destruction of both packets.

collision avoidance
Any technique that reduces the possibility of another collision on a retry transmission of a packet. See also persistance, slottime, dwait, retry, polling.

Same as professional-means. This is any service that is run by people who are paid to run them. That means Internet, cellular networks, corporate links, corporate satellites, state radio, state microwave, state fiber, dark fiber, and anything else some ham doesn't personally maintain at their whim.
Amateur radio managed hardware that is locked behind a door or gate is a grey area that we have to be really careful about because in times of emergency, we can't get to the gear to make adjustments or make repairs.
It is a grey area and not a black area because at least we get to design and specify the ham gear, making it easier for us to manage in times of crisis than fully commercially operated equipment could be.

communications protocol
The rules governing the exchange of information between devices on a data link. See also protocol.

compressed forwarding
Forwarding between BBSs using a data compression technique to reduce the amount of data to be exchanged. This is common between FBB BBSs.

conference node
A specialized node that allows many users to connect and communicate with each other. Resembles an Internet Relay Chat conference. Some node software like G9BPQ, TheNET X1-J and NOS have built-in conference modes. Also called crowd or chat nodes. See also: JNOS, MSYS, NOS, TheNET.

refers to a packet protocol or service that does not have the concept of a "connection". Packets may be sent at will, without prior arrangement or need for connection setup/teardown procedures. An analogy would be the postal service where letters (datagrams) can be sent anywhere without prior arrangement.

refers to a protocol or service that requires that a logical or virtual "connection" first be established with a special procedure before data can be sent. Another procedure is used to "tear down " the connection when it is no longer needed. The amateur packet AX.25 level 2 protocol is connection oriented. An analogy would be the telephone system where you must callup (connect to) another phone before talking and hang up (tear down) the connection when you are finished.

Connection Oriented Network Service (see connection-oriented, virtual circuit).

Contention is when 2 or more stations on a channel want to transmit at the same time. If they do, it may produce a collision. See also collision, HTS.

converse mode
In a standard user station TNC, Converse mode is an option where when connected to another stations the characters sent from the keyboard to the TNC are observed and only printable text characters are recorded without processing. Control characters, like backspace and ENTER are interpreted by the TNC and used to control when packets are sent and for editing of the line to be transmitted. The opposite mode is transparent mode where characters are sent over the air without being interpreted.

conversion program
Any software program that converts binary files into ASCII text files for easier transmission on packet radio. Examples are 7-Plus, R95, uuencode, etc.

Carrier Operated Relay. A circuit that closes a relay (or turns on a transistor) when a radio carrier is detected. This is how a radio repeater knows to turn on its transmitter when it receives a signal on its input frequency.

The area in which a transmitted signal can be heard effectively is that transmitter's coverage. Usually coverage refers to both transmit and receive. Wide area coverage means that the station can be heard and can hear over a wide area. See cellular, WAN, LAN.

Central Processing Unit. This is an Integrated circuit contains an arithmetic processor unit, an instruction processor, address bus drivers, data bus drivers, registers. Generally a CPU needs memory, data memory, clock, and input output components to become a computer. Examples: 1802, 6502, 8088, Z80, 68000, 80286, ARM, BlackFin, Pentium, PowerPC
See also MPU.

Cyclic Redunancy Check. The error checking procedure that verifies a packet. See also block check character, checksum, FCS.

CROWD node
This was a name given to TheNET chat engines used in the NEDA network between 1990 and 2000.
See conference node.

Carrier Sense, Multiple Access. A system of packet operation that requires that all stations on a channel wait for the channel to be quiet before transmitting. CSMA dates from the Vancouver VADCG packet TNC which did not have over-the-horizon range. The addition of over-the-horizon capability to packet radio negated the usefulness of CSMA but CSMA was never replaced. Most amateur radio packet uses CSMA.

Carrier Sense, Multiple Access with Collision Avoidance. A CSMA system with a method to reduce repeated collisions between two stations trying to transmit at the same time. One example of collision avoidance is the FRACK/DWAIT method where a random time delay passes before a packet transmission is retried.
This mechanism does not prevent over-the-horizon packet collision events but does cause the channel to run slower. If used properly this could enable a link to be slow enough that collisions would not occur, even though the Carrier Sense aspect is not detecting the over-the-horizon transmissions.
See also persistance, polling.

Clear To Send. A control line on a RS-232 port (pin 5 on DB-25) which indicates that the device is turned on and ready to receive data. Compare with: RTS or DTR which is the line that indicates that a device is got data ready to send. See also RS-232, RTS, DTR.

A Kantronics radio product. These devices are 10 watt crystal controlled Amateur Radio transceivers operating in the 430 to 450Mhz range. They are digital radios in that they do not accept an analog input. They are intended to be connected to a packet radio modem for use at 9600 to 19200 baud. They actually can go to higher baud rates but the modulation bandwidth is narrow enough that this doesn't work very well.

Demand Allocated Multiple Access
This is a scheme where a master station on the channel could allocate time to client stations so they could transmit traffic to the channel. This is similar to a polling scheme. DAMA was implemented as part of the FlexNET packet network node.

dark fiber
Fiber-optic cable between two customers where there is no active equipment between the two customer sites. If you have a factory in town A and a business office in town B you could have a fiber-optic cable laid between the sites along right-of-ways owned by telephone or cable or power utility. The ends of the fiber are physically in the control of your company and you are hooking up your own equipment to the ends of the fibre. There is no active electronics along the fiber between your two sites.

The numerical representation of information. Usually expressed as binary bits or hexadecimal bytes.

A TNC manufactured and marketed by Kantronics. The DataEngine has two HDLC radio ports and one serial port. The modems are plugged in and are available up to 19.2 Kbps.

data hub
A regional BBS which acts as a distribution center or hub for the local BBS network. It also acts as a consolidation BBS for outgoing messages. Compare with a BBS network that forwards in a linear manner, that is from one BBS to the next to the next and so on.

data rate
The basic rate at which data is transferred on a circuit. Often referred to as "baud rate" (which is like saying speed speed) but more correctly should be bits per second or bps. See also baud, bps.

data set
A telephone industry name for a modem.

Information packets in a connectionless environment. Datagrams are completely self-contained as far as the network is concerned. The information needed to get each datagram to its destination (including, but not limited to, full source and destination addresses) is carried in each datagram. An analogy would be a letter sent in the postal system. The envelope contains all of the information (name and address) necessary to deliver the letter (datagram).

DB-9 connector
See DE-9 connector

DB-25 connector
The 25 pin subminiature D shaped connector used on many digital devices as a RS-232 (serial) port. See also DE-9 connector.

Data Carrier Detect. DCD is a signal indicating the presence of data on the communications channel. The TNC uses the DCD signal to hold-off the transmitter when the channel is occupied. Some TNCs and modems employ a "DCD" that simply indicates the presence of a RF carrier or noise energy on the channel rather than true Data Carrier Detect. See also hold-off, modem, TNC.

DCD hold-off
See hold-off.

Data Communications Equipment. Usually refers to a modem or any equipment that receives data from a DTE (terminal or computer).

DE-9 connector
The 9 pin sub-miniature D shaped connector used on IBM AT computers and many other digital devices as a serial port connector. Often called (wrongly) a DB-9 connector. See also DB-25 connector.

To the right is an image of 2 connectors, a DE-9 male at the top, and a DE-9 female on the bottom.


DE-9 hood
The hood refers to a covers used to finish a DE-9 connector, giving it a handle, electrical protection, and mechanical soundness.

The image to the right shows a kit of parts used to assemble a DE-9 hood.


See DED Host.

DED Host
Firmware written by Ron WA8DED that allows a computer to control a TNC with greater interaction than with KISS mode. Also called DED firmware or Host mode. This firmware can be operated using a dumb terminal by a human but it isn't very verbose.

dedicated link
A point-to-point link between two dedicated ports for the exclusive use of those ports or nodes. The name of a newsletter published by NAPRA. See HTS, backbone, NAPRA.

dedicated port
A port designated for a specific purpose with only one other station on the frequency, usually a tie-in to a server or other network hardware. See dedicated link.

defined neighbor
Another name for G8BPQnode/TheNET's locked route.

The deviation of a FM radio is the maximum change or shift in the carrier frequency during modulation. It is usually expressed as peak deviation in kilohertz.

An amateur packet BBS program written by Joe N3DFD.

slang for the shifting of an AFSK signal back and forth between the two tones.

See digipeater.

A software and modem package designed to emulate a TNC on a Commodore 64 computer. The software was written by DL2MDL and others while the modem was designed by Willy YV1AQE. The software and modem info is distributed in North America by Barry W2UP and is described in 73 Magazine Aug 88.

A store and forward digital repeater that receives a packet, checks it for errors and retransmits it a short time later. It takes no responsibility for the delivery of the packet. It does not ACK reception of a packet. See also simplex digipeater, duplex digipeater, store-and-forward, real time, repeater. Compare with: full duplex regenerative real-time repeater, which repeats the data at the same time without delay but does not check for errors. Also compare with: node which is normally a store-and-forward but which is "smarter" and takes responsibility for the delivery of the packet toward its destination and acks every packet received correctly. All user TNCs have digipeater capability but current practice discourages use of digipeaters except where it is necessary to get to a network node. Some network nodes (eg. TheNET 2.10) will not accept a digipeated signal.

digital signal
An electrical signal that changes in discrete unambiguous steps, each representing a numerical data value, or logic state.

DIN >Deutsche Industrie Norm (English
German Industrial Standard). A german standards organization responsible for setting industrial standards of products made in Germany. A european equivalent of ANSI or possibly EIA. The most visable evidence of their standards are the various DIN plugs used in consumer electronics products. A 5 pin DIN socket/plug is used as the radio port on most TNC-2 clone TNCs.

Diode Matrix
A circuit in which the RS-232 ports of a number of NET/ROM nodes or ROSE switches are connected together with isolating diodes. Any node can communicate with any other node on the matrix. See also Hexipus, octopus, dogbone.

Domain Name Service. A TCP/IP server that acts as a IP address database linking hostname.domain_name to IP address. See also domain name, FQDN, host, hostname, IP address, TCP/IP.

Department of Communications. The former name of the Canadian federal department that regulates all aspects of radio communications in Canada. It was also called Communications Canada. The new name is Industry Science Canada, Communications Division. The Canadian equivalent of the FCC. See also ISC, FCC.

Digital Operators Emergency Radio Service. An active packet network group in Plattsburgh, N.Y.

Two diode matrices connected together with two TNCs and a wireline link. See diode matrix, wireline link.

domain name
The IP name designating a group of host computers that are logically (though not necessarily physically) connected together. Domain names are like IP addresses; periods separate parts of the name, with each part representing a different level in the domain hierarchy. But the domain name is ordered in reverse, its highest level portion is at the right, the opposite of IP addresses. An example of a domain name would be ampr.org. which designates all the host computers operating in the AMateur Packet Radio domain which in turn is one of the many ORGanizations in the INTERNET system.

A gateway server that links packet radio to a MS-DOS computer and allows one to operate the computer remotely via packet radio.

Digital Orbiting Voice Encoder. A station aboard OSCAR 17 satellite.

A circuit from a node to a user, initiated by the node on command from a distant user.

The process of sending data from a BBS or other server to the user. Usually refers to the transfer of large files from a server to a user.

Digital Radio Systems Inc. Best known for a line of PC plug-in TNC cards.

Digital Signal Processing. A modern technique of analyzing analog signals by converting the analog signal to a digital form and processing it with a speciallized computer circuit.

Data Terminal Equipment. Usually refers to a terminal or computer or any equipment that generates or receives data.

Data Terminal Ready. One of the RS-232 signals (pin 20 on DB-25) that indicates that the computer or terminal is ready to send data. It is similar and sometimes interchangable with RTS (ready to send).

dumb terminal
An ASCII terminal with video display and keyboard that can send and receive ASCII text but cannot do any computational operations.

duplex digipeater
like a simplex digipeater, except that different receive and transmit frequencies are used. Compare with: Full duplex real-time repeater which repeats received data at exactly the same time. See also digipeater, store-and-forward, real-time.

A random delay in sending a retry packet. Used as a collision avoidance system. See also persistance.

See PacketCluster.

Dynamic rerouting
In a network where redundancy exists in the backbones from one part of the network to another, some types of network software allow the network to recover automatically from a backbone failure by rerouting traffic through alternate paths. This is called "dynamic rerouting" as it can adjust dynamically to a changing network.

dynamic routing
An automatic process used by some network protocols such as NETROM/TheNET, that sets up and maintains network routing tables based on information received from neighboring nodes. Compare with ROSE, a network protocol in which the routing tables are setup and maintained manually by the node-op. See also dynamic rerouting, node broadcast, NET/ROM, ROSE, TheNET.

also email. Electronic Mail. Any messages sent over the BBS system or through the INTERNET system.

Easy Mail
MFJ's version of a personal bbs in a TNC.

Electronic Industries Association. A standards organization in the USA made up of representatives from most of the major electronic manufacturers. EIA formulates and controls standards defining the electrical and functional of all types of electrical and electronic equipment. The RS-232-C interface is an EIA standard.

The imitation of any device or system (including physical systems such as weather) by means of software running in a computer system. For example, Baycom software running in a computer (in conjuction with a simple modem) will imitate and perform all the functions of a TNC. Baycom is therefore said to "emulate" a TNC.

envelope delay distortion
See group delay distortion.

Erasable Programmable Read-Only Memory. A non-volatile memory IC used in TNCs and other computers to hold the operating program. It can be erased and reprogrammed a large number of times.

Exposed Receiver Syndrome. This is a condition where a packet station, be it node or user, is unable to transmit due to the fact that it perceived the channel as being active almost continuously. This can be caused by Hidden Transmitter Syndrome (HTS) and is often the case when a node is located on a high hill with surrounding metro areas. It is also a serious problem on widely used WAN channels such as 145.01 MHz. See also HTS, WAN, LAN, hold-off.

even parity
An error checking method in which each character must have an even number of 1 or "on" bits in its ASCII binary number.

eye pattern
A pattern produced on an oscillioscope to show jitter and phase distortion of a data signal transmitted on a communication channel or through a particular component such as a modem. The eye pattern is produced by triggering the scope with the original data signal and displaying the received data stream on the horizontal trace.

FAcsimile(X). A method for transmission of pictures and graphics data. The graphics data may be text material.

An increasingly popular amateur BBS software written by Jean-Paul F6FBB and others.

Federal Communications Commission. The US federal commission that regulates all aspects of radio communications in the United States. The FCC is equivalent to ISC Communications Div (DOC) in Canada.

Frame Check Sequence. A 16 bit (2 byte) number included with each frame in the packet used for error checking.

Forward Error Correction. A technique of error correction in which packets or AMTOR groups combine the data from two or more transmissions to yield less errors. In AMTOR FEC mode, the data is sent twice and the receiving station(s) record all known characters without resorting to an ARQ ACK/NAK transmission. See also AMTOR, ACK, ARQ.

Software stored permanently in a ROM or EPROM IC.

A data character (01111110) used to delimit packets (beginning and end) and to separate multiple frames in one packet transmission. The same character is often used during the TXDelay to help synchronize the TNC receiver circuits at the beginning of packets. Should 6 binary ones occur together in the text of the packet, a process called bit-stuffing is used to modify the character so that it can not be confused with a flag character. See also bit-stuffing, TXDelay. In computer terminology, a flag is a single status bit included in an information field. For example, in a BBS program a number of flags are used to indicate whether a message has been read, forwarded, killed, old, etc.

flat network
A flat network is a system of dual port nodes where one of the ports is on a common zoo channel port between all other nodes. It is said to be flat because the network topology is flat. A flat backbone port is not on 2m or HF. This port specification is also used where the other stations on frequency are not able to operate with respect to Hidden Transmitter Syndrome or if locked routes and connect disable are not used on all adjacent nodes. See Zoo channel.

A critical, negative and/or insulting response to a BBS bulletin or message.

A network protocol developed by the FlexNet Group in Darmstadt, Germany
The software ran on an embedded machine or on a MSDOS PC and supported connection into and out of nodes on the system, much as does TheNET and G8BPQ. FlexNet came after TheNET and had many modern features not seen before or after.
Alas, FlexNET appears to be unsupported at this time (late 2014).

flow control
The control of data flow on a communications circuit by software (XON/XOFF) or hardware means (RTS/CTS). See also handshaking, RTS, CTS, XON/XOFF.

flood bulletins
BBS bulletins that are forwarded to all BBSs in a given geographic area (like water flooding a skating rink) or a group of BBSs that specialize in a common field. "Flood" regions can be local, regional or national or alternatively they could be a special interest group such as RACES.

flood header
The bulletin header information that specifies what geographical region or special interest group is to receive a flood bulletin.

Frequency Modulation. A method of transferring data or voice information over a carrier signal such as a radio wave. FM is done by changing the frequency of the carrier in direct proportion to the waveform (audio or digital). The amount of change is called deviation and is usually around 3-5 KHz peak for a typical voice radio.

forward file
This is the disk file in a packet bulletin board system (PBBS) that is responsible for directing the autoforwarding operation. By making entries in this file, the PBBS sysop may select what packet paths are used to each PBBS that is forwarded to, when each operation is performed and what traffic is sent during each sequence of the forwarding operation. See also autoforward.

The transferring of messages between BBSs.

forwarding frequency
A channel or frequency used exclusively for transferring messages between BBSs.

Fully Qualified Domain Name is the combination of the complete IP hostname and complete IP domain name to designate a unique IP address. For example ve2dm.ampr.org. The period at the end is essential to the FQDN as it indicates that is the end of the address.

FRame ACKnowledge delay. This is the time after a packet is transmitted by a TNC before the TNC decides that a frame acknowledgement is not going to occur. At that point the TNC performs backoff (waits a random time) and retries the frame transmission.

A single block of data along with necessary addresses and control bytes that can comprise a packet. A packet may contain from 1 to 7 frames sent together.

Computer programs released into the public domain for the unrestricted use by anyone at no charge.

Frequency Shift Keying. A method of digital modulation where the carrier is switched between two distinct frequencies. This is the technique used on HF packet and many of the high speed modems such as the G3RUH 9600 bps system.

File Transfer Protocol. A TCP/IP protocol that transfers files (ASCII text or binary) between TCP/IP host computers.

Communications in which reception and transmission take place at the same time. In radio, this means that transmission and reception are on two separate channels. See also half-duplex, repeater.

G3RUH modem
A 9600 bps plug-in modem for TNC-2s and other amateur TNCs. It was developed by James Miller, G3RUH. Circuitry contains adaptable filters to adjust for bandwidth limitations in commercial radios and a"randomizer" circuit to prevent DC offsets on modulated data. Similar to but may not be totally compatable with K9NG modem. Believed to be compatable with the new TAPR 9600 bps modem. See also modem, K9NG modem, TAPR, HAPN.

John G8BPQ is the author of a widely used packet switch software that, in the 1990s, emulated a multi-port TNC on a IBM PC or clone. This software normally runs in TSR (Terminate and Stay Resident) mode and allows routing from an AX.25 network or TheNET system directly to the PBBS or other program running on the PC. It also performs TheNET routing across its radio ports.
As of 2014, John is still working on his software which now runs as an application in Linux on Wintel computers and embedded ARM platforms, in Unix on the Macintosh, and in various flavors of Microsoft Windows.
G8BPQ node software can support various TNC hardware types and modes including HF packet systems, audio card virtual TNCs etc.

A very general term for anything that connects two networks together especially two networks with different protocols or different parameters. For example between a VHF 1200 bps network and an HF APLINK station. In the ARPA world, "gateway" has a much more specific meaning: a packet switch that handles IP datagrams. Gateway was also the name of a packet newsletter published by ARRL and now included in QEX magazine.

group delay distortion
Also called envelope delay distortion. A distortion of the data signal produced when the different frequency spectral components of the digital signal are phase shifted by different amounts resulting in a distorted pulse shape. For best results, it is important that radio filters, amplifiers and other components in the communication system have a constant phase shift across their bandwidth. This is called "flat group delay" characteristic.

Graphics Packet. GP is an icon driven DOS packet terminal program written by Ulf DH1DAE. Features include BBS listing capture, message number transmission, off-line editor, auto real time 7PLUS decoding and "QSO spy". The program is "Hamware" and free to all radio amateurs.

A BBS program written by Doug, N2GTE. It is reported to be compatable with FBB BBS.

See Hierarchical routing.

Communications in a duplex system arranged to permit operation in either direction but not in both directions at the same time. See also full-duplex, digipeater, simplex, simplex digipeater, semi-duplex.

Computer programs released as freeware specifically for use by radio amateurs at no charge. There may be restrictions limiting the commercial use of the programs. See also freeware, shareware.

The exchange of data or signals between sending and receiving devices that ensure that the circuit is ready for communications. On RS-232 linked devices, the RTS (or DTR) and CTS lines are used for hardware handshaking or Control-S/Control-Q characters for software handshaking. On packet radio circuits, supervisory bytes in the packet and ACK and other control frames are used for handshaking. See RTS, CTS, DTR, RS-232.

Hamilton Area Packet Network. An active amateur packet group in Hamilton, ON best known for the development and marketing of a 4800 bps modem (for installation in TNC-2 or clones) and plug-in TNC cards for PCs. For more information,contact: HAPN, 5193 White Church Road, Mount Hope, Ont L0R 1W0. See also HAPN-T modem.

HAPN-T modem
A 4800 bps add-on modem card for TNC-2 (and clone) TNCs which uses bipolar pulse modulation and can be used with most any radio transceiver. See also HAPN.

HAZardous MATerial. A database of hazardous material properties that is available on some BBS systems.

High-level Data Link Control. The ISO level 2 link level protocol on which AX.25 was based.

The R: lines attached to a BBS message that indicate the forwarding path that the message has taken. The header lines contain the date and time, message number, and hierarchical address of each BBS that handled the message. Header may also describe the TO, From and @BBS address fields of the message as well as the subject line information of the message.

header line
See header.

heard list
On some user TNCs and on certain node and BBS systems, the most recent stations heard are listed in a heard list. On a TheNET Plus node, the user stations heard in the last 15 minutes are listed in a heard list.

Hexadecimal. Numbers to the base 16 (0-9,A-F).

An Amateur packet group based north of Toronto in the Barrie, ON area.

A six port diode matrix card developed and marketed by NEDA (North East Digital Assoc). See Diode Matrix, octopus, NEDA.

hidden terminal syndrome
Another name for hidden transmitter syndrome.

hidden transmitter syndrome (HTS)
A condition in a CSMA packet system where several stations who cannot hear each other (they are HIDDEN TRANSMITTERS) are allowed to transmit at the same time and thus cause collisions thereby reducing throughput on the channel. It is also called the hidden terminal syndrome in some areas. See also CSMA, collision, throughput. Compare with: ERS exposed receiver syndrome, which is the inhibiting of transmit at a high node site due to other nodes on the same channel at a distance. They may not be strong enough to trash the local packet but reduce the throughput due to the delayed response.

hierarchical address
A geographical addressing system for stations involved in the amateur BBS system. The hierarchical address is a series of abbreviations of increasingly larger geographical areas (each abbreviation is separated by periods) within which the station resides. For example, the hierarchical address of a major Montreal BBS is VE2FKB.#MTL.PQ.CAN.NA which in effect says that VE2FKB is at Montreal which lies within Province of Quebec which lies within Canada which lies within North America. The state/province abbreviations used are those normally accepted by the postal system. National abbreviations are set by international agreement.

hierarchical routing
A BBS forwarding technique using the hierarchical address as guidance.

The process by which a TNC delays transmitting until the DCD indicates the channel is clear. See DCD, collision avoidance.

home BBS
The "home BBS" is the full service BBS at which a user receives his mail and to which all mail for that user is addressed in the format <user_callsign> @ <home_BBS_callsign>. It is very important that each user chooses ONE and only one home BBS and that it is a "full-service" BBS known to the BBS forwarding system. Otherwise the user's messages will get hung up in the system.

The computer or terminal attached to a TheNET node when operating in host mode for sysop entry to the serial port. Host is also the name given any computer running TCP/IP. See also hostname, remote host, TheNET.

host mode
A program written by Ron WA8DED which allows a computer to control a TNC directly. Some BBS programs took advantage of the command language in Host Mode to control the TNC and to allow multiple users to connect to the BBS at the same time. TheNET incorporates a very small subset of the Host Mode command set. Also called DED Host software (or firmware when stored in an EPROM). Host Mode is also used to refer to the condition where a node has a CRT terminal or computer plugged into it that will be used in ASCII mode (not using networking protocol).

An alphabetic alternative to the numeric IP address designating a single computer running TCP/IP. The hostname is usually written in lower case. For example: a computer that Dino, VE2DM runs as a test node has a hostname of test.ve2dm whereas its IP address is . Obviously the hostname is easier to remember. See also domain name, FQDN, Internet address, TCP/IP.

Hidden transmitter free. See HTS free.

See Hidden Transmitter Syndrome. Also called Hidden Terminal Syndrome.

HTS free
A packet channel with no hidden transmitters. This may be a dedicated point-to-point link with only two stations on it, a shared channel on which all stations can hear each other or a shared full duplex channel with a repeater to link the stations. See also hidden transmitter syndrome, repeater, point-to-point link.

A proprietary but recently license-free bus created by NXP Semiconductors (formerly Phillips). The I2C bus uses two wires and a reference ground to communicate between multiple digital devices. The bus is multi-drop and multi-master. Multi-drop means that more than one client can be on the bus and may be addressed by a master. Multi-master means that there can be multiple stations commanding the bus. In the case of the I2C bus, only one master can be sending or reading at a time.
The I2C bus is usually used across a single board and there are many inexpensive chips, like memory devices, temperature sensors, serial number repositories, which are addressable using I2C compatible masters.
The two wires are a clock wire, driven by whatever device is presently mastering the bus, and the data wire, driven by the master during the address phase and command phase, and the master or slave, during the data phase.
The I2C bus has multiple speed ranges, and multiple means of addressing, providing different quantities of addressable units on a given bus.

See ROM image.

Information frame
The part of a message or frame containing unique information is called the information frame. Other parts of the message include sync and CRC. See packet.

The Internet is a public system of computers which communicate over commercial lines (usually telephone or leased telephone lines) using TCP/IP. Most Internet terminals are at government and commercial research facilities and educational facilities. Use of the Internet network is free although use of the computers that are hooked into the Internet may not be. Most people who have access to the Internet either pay a fee or have connection to the network from work or school.

Internet address
An Internet address is the total e-mail address of a user in the Internet system. It consists of the user's log-in name and the FQDN (fully Qualified Domain Name) separated by an @ character. See also domain name, e-mail, FQDN, host, hostname, Internet.

Internet Protocol. The core protocol of the ARPA suite. IP is a simple connectionless (datagram) protocol that handles addressing, fragmentation and type-of-service routing in the heterogeneous internetwork environment. See TCP/IP, KA9G, ARPA Suite, connectionless.

IP Address
A numeric address designating a host computer running TCP/IP. For example: VE2DM's test computer is . Compare this with his hostname.domain_name test.ve2dm.ampr.org. See also domain name, FQDN, host, hostname, Internet address, TCP/IP.

Intermediate System. ISO's term for a packet switch.

Industry Science Canada. ISC is the Canadian government ministry that merged Communication Canada with Science and Technology. ISC is now responsible for the control of all radio communication in Canada. See also DOC, FCC.

International Standards Organization. ISO formulates and publishes specifications for everything from screw threads to computer communication protocols. See also OSI.

jitter - variations in the phase or amplitude of a data modulated signal having no relationship to the data. On amateur packet signals, phase jitter may cause errors in decoding the data.

A version of KA9Q NOS TCP/IP software written by WG7J that combines a BBS, node, and conference server with TCP/IP functions.

K9NG modem
A 9600 bps modem designed by Steve K9NG and marketed by TAPR. It uses the same modulation technique as the G3RUH modem but does not have the adaptive filters. The "randomizer" circuit from the K9NG modem is used in the G3RUH modem. It may be compatable with the G3RUH in some circumstances but not guaranteed. It has been replaced by the new 9600 bps modem from TAPR. See also modem, G3RUH modem, TAPR, HAPN-T modem.

KA9Q Internet (KA9Q NOS)
Original name for TCP/IP or NOS amateur packet software. A C software package developed by Phil Karn KA9Q and others. Implements the major elements of the ARPA protocol suite: IP, ICMP, TCP, UDP, Telnet, FTP, SMTP and ARP. Also implements subnetwork drivers for SLIP, KISS, AX.25, Ethernet and Appletalk. Primary environment is the IBM PC (and clones), but has been rewritten for 68K- based machines like the Commodore Amiga and Apple Macintosh, also to UNIX system 5 environments. See also NOS, TCP/IP, Internet, ARPA Suite.

Kantronics All Mode. The multi-mode TNC made by Kantronics.

A level 3 networking protocol written and supported by Kantronics. It is not compatable with NETROM/TheNET or other network protocols and must communicate with them at level 2 AX.25 protocol. See also K-NODE.

Kantronics designs, manufactures and markets a range of amateur packet products including the popular KPC TNCs and KAM multimode controller.

keplerian elements
The set of numbers used to completely describe the motion of an object in space such as a satellite. Also called orbital elements.

Communications between two packet user stations in real time. Tends to be rather slow unless both operators are fast typists.

The process of deleting a message from a BBS after reading it or for other reasons.

Keep It Simple, Stupid. A TNC operating mode where the TNC merely translates packets between half duplex, synchronous HDLC on the radio port and full duplex asynchronous SLIP framing on the host port; the host computer must implement all higher level protocols, including AX.25 if it is used. Gives the host computer full access to and control over all fields in each packet. Compensates for the lack of a HDLC hardware controller on many computers. The KISS TNC is only responsible for TX delay and DCD hold-off. Kiss is used with TCP/IP hosts and also often used with BPQ and other such PC based packet switches. See also TCP/IP.

An operating mode in the Services Section of a MSYS PBBS system that operates like and is compatable with a Kantronics KA-Node. See also KA-Node, MSYS.

See local area network.

Link Access Procedure, Balanced. AX.25 is based on the Balanced Link Access Procedure of the CCITT X.25 standard. LAPB in turn conforms to the HDLC standard.

A DOS packet terminal program written by Joe, N3DFD.

A shareware terminal program written and supported by Joe, G3ZCZ. See also YAPP, Paket.

link layer
Level 2 in the 7 layer OSI computer communications protocol set. AX.25 is the amateur packet level 2 protocol.

local area network
A digital network channel covering the smallest group of stations in the hierarchy of trunks, backbones and workstations. LAN would mean local area, WAN is wide area.
For ham radio purposes a LAN could be all of the simplex partners of a digital station, or it could be all of the stations sharing a token ring or polling system. It could also be all of those stations that are local to one central station.
Historically a LAN was all of the stations in range of a particular server or service.

locked node
An entry in the nodes table of a TheNET node that has been manually entered by the sysop and which will not be modified by the dynamic routing algorithm. A locked node is used by the sysop as a network management device.

locked route
An entry in the routes table of a TheNET node that has been manually entered by the sysop and which will not be modified by the dynamic routing algorithm. A locked route is used by the sysop to modify the quality of a route to a neighbor node or to prevent an unreliable route to a neighbor node from affecting the routing process.

A test in which the output of a modem modulator or other full-duplex digital device is looped back to the input of the demodulator or device. The looped back signal may be either analog or digital.

mail box
A personal bbs in a TNC. Sometimes also refers to any BBS system handling personal mail. See also Mail Drop, PMS, Personal BBS.

Mail Drop
AEA's version of a personal bbs in a TNC. See also PMS, personal BBS, PakMail.

One of the two possible binary states in a data communications system. The mark is the resting state in an asynchronous serial system. The negative voltage state on a RS-232 port is called mark. One of the two tones in an AFSK modulation is mark. Compare with: space, which is the opposite state.

See diode matrix, hexipus, octopus.

matrix monitor
A matrix monitor is a hardware or software device that can display the data passing across a diode matrix in a form that is legible and informative. G8BPQ switch software includes such a program.

An amateur BBS program written by Jeff WA7MBL. See also YAPP.

Multimode Communications Processor. A fancy name for a multi-mode TNC such as the KAM.

MFJ Enterprises Inc. MFJ designs, manufactures and markets a range of amateur packet products such as the popular MFJ-1270 TNC (TAPR TNC-2 clone) used for network building as well as other amateur related items.

Message ID. An identification number given to all messages entered on a BBS system. For bulletins it is often the same as the BID. See also BID.

Russian (Soviet) space station whose cosmonauts regularly use packet radio to communicate with amateurs around the world. The callsigns used all end in MIR.

See alias.

Montreal Packet Net. A group of amateurs from Montreal, Quebec who were responsible for the very first amateur packet radio broadcast on May 31, 1978.

MOdulator/DEModulator. A device which takes the data modulated signal (RF, audio or pulse) received from the communications channel and restores the data to a form that can be used by the CPU in a computing device (or that can be read on a terminal). At the same time it converts data from the computing device to a form that can be transmitted out on the communications channel. Most TNCs contain an internal 1200 bps modem and have space to plug-in another modem for a different radio data speed. See also TNC, G3RUH modem, K9NG modem, HAPN- T modem.

modem header
The connector inside a TNC-2 clone TNC used to connect an external modem to the TNC for higher speed or different mode of communication. All the data and control lines from the CPU/SIO to the modem pass through this connector.

Microprocessor Unit. This is similar to CPU (Central Processor Unit) except usually an MPU is assumed to have all of the necessary parts to be a fully operational processing element. It includes clock, instruction engine, code memory, data memory, input/output buffers. Usually, these days, an MPU assumes a single chip machine where only the clock crystal (if even that) is external to the integrated circuit.
MSP430, PIC, ARM7, 8051, 68HC08 are all examples of MPUs.

An amateur packet BBS software written by WA8BXN. Versions also contain switch node, dxcluster and conference node modes. See also BBS, node, K-Node, NET-Node.

MTL/WQC Network
A network of nodes in Montreal Area dedicated to linking Montreal west to Ontario and south into northern USA. Main linking is through a hub repeater and node stack at VE2RM site at Rigaud, QC.

A process by which a user can connect to several stations at once.

Negative AcKnowledgement. A packet or AMTOR ACK response that indicates that the data was NOT received correctly. See also AMTOR, ACK, handshake.

Northwest Amateur Packet Radio Association. This is an association founded in 1983 to promote packet radio in the Pacific North West region of USA. They publish a newsletter called "Dedicated Link".

North East Digital Association. NEDA was an association that was formed in 1989 by by KA2DEW, WA2WNI, WA1TPP, K1MEA, NQ1C and WA2VAM to support and promote efficient packet network development. Development of network concepts and standards as well as the writing and publication of up-to-date network and general packet information were goals of NEDA.
NEDA promoted into existence a network that at its furthest reaches enabled connectivity from Detroit to Prince Edward Island though the NEDA participating nodes included Ontario, Quebec, Pennsylvania, New York, Vermont, New Hampshire, Maine, Massachusetts, Rhode Island, Connecticut, New Jersey only.
NEDA met its Constitutionally mandated conclusion in 2000 and disbanded itself.
NEDA had several interesting novelties. Its Constitution forbid it from owning network hardware. It was entirely an educational, publishing, and supervisory club. They did network node management but of network hardware they did not own. NEDA put out hundreds of pages of journals per year for 11 years. The NEDA network had hundreds of network nodes connected via hidden-transmitter-free network links, most of which were 1200 baud point‑to‑point links delivering hundreds of times the throughput typically associated with a packet radio connection.
NEDA's journals were called Annual, Quarterly, Report, and Maps.

In a network of packet nodes, the neighbor of a node is any node that is talked to DIRECTLY on either the serial or radio ports.

New England Packet Radio Association. An amateur packet group based in the New England/Boston area.
NEPRA was founded by several early packeteers including W0RLI and K1UGM.
The club was especially interested in building and maintaining packet bulletin board interconnectivity and promoting access to the bulletin boards by the BBS users. NEPRA made it its mission to keep new users from generating contra-traffic which would interfere with the activities of the BBS sysops.
The club met northwest of Boston in Concord and Billerica Massachusetts.

A operating mode within the Services Section of a MSYS PBBS system that emulates a NET/ROM or TheNET node. See also MSYS, K-Node, NET/ROM, TheNET, node.

A proprietary product of Software 2000, Inc (W6IXU). Consists of ROM firmware for the TNC-2. Implements AX-25 at the link layer (L2), with ad-hoc protocols at the network (L3) and transport layer (L4). Also provides a command interpreter and "transport level bridge" that patches incoming or outgoing regular AX.25 level 2 connections to internal transport layer connections. Uses datagrams at the network layer, virtual circuit at the transport layer. Provides automatic routing between NET/ROM nodes but the user is still responsible for "source routing" between the end NET/ROM nodes and the ultimate source and destination. Compare with: ROSE, a network protocol which is similar in function but uses manual management of routing tables rather than automatic dynamic routing. See also TheNET, BPQ, ROSE.

Any group of stations participating in communications as a set, where any one station can interact with more than one other station. A traffic-net is a network. So is a set of three PCs plugged into an EtherNET switch.
In packet terms a network is considered to be a set of nodes with interconnections.

network co-ordinator
The person or group responsible for the orderly development of the packet network, including channel frequency co-ordination but more importantly the co-ordination of internode linking and the control of LAN coverage areas so that the number of users that can be served at the same time is maximized. The network co-ordinator must also try to resolve disputes between various network user groups that would endanger the network efficiency. The network co-ordinator must be very well informed on the latest network techniques and the identity of all operating nodes and servers in his region. network layer = Level 3 of the seven layer OSI communications protocol set. The network layer specifies the communications between adjacent nodes or networks and interfaces with the User at the level 2 link layer and with distant nodes at the level 4 transport layer protocol.

A node is an active element in a network. This can mean anything from a user station to a server to a network switch. Traditionally a node in packet radio is an intelligent router of real time data which has a unique identity, and where a command line supervisory session can be established.
Since TheNET has only one radio per TNC and since each TNC has a unique identity, it is unclear if a 3 port TheNET switch is actually three separate nodes. In normal usage, the "node" referes to the entire site, and not to an individual command interpreter. See G8BPQ and TheNET.

node broadcast
In a NETROM/TheNET node network, a node broadcast is one or more UI frames sent by the node at regular intervals containing routing information on all the nodes in its node table. The neighbor nodes use these node broadcasts to update their node routing tables. Node broadcasts are the key to dynamic routing method of route table maintenance. Node broadcasts add a significant amount of overhead to the channel. Compare with ROSE: A network protocol that uses manual routing table maintenance and thus does not need node broadcasts. See also dynamic rerouting, dynamic routing, NET/ROM, TheNET.

node cluster
See node stack.

node hopping
When the user explores the network by the process of connecting from one node to the next along a path and checking the routes available by reading the nodes table, routes list and INFO response. It is a good way to learn about the network and what is available on it. Also called route stepping.

The person(s) responsible for the software and parameters of a node stack. Also called site sysop.

node stack
Two or more nodes on one site interconnected by a diode matrix. Also called a node cluster.

A packet radio networking organization in Germany whose members created and popularized TheNET packet radio network nodes. Web link

Node Operating System. A TCP/IP based node software. See also JNOS, KA9G, TCP/IP.

Non Return to Zero. A binary code format in which binary ones and zeros are represented by two discrete voltage levels and the voltage remains at the indicated level for the duration of the code bit. Compare with RZ or bipolar pulse modulation in which the signal would return to an average level between bits. The name NRZ is somewhat confusing but it may come from the magnetic recording industry where zero indicated an unmagnetized state on the tape and binary ones and zeros were indicated by positive or negative magnetization. NRZ is the form that most binary signals take within computer circuitry. See also NRZI.

Non Return to Zero Inverted. A binary code format in which a data 0 produces a transition (either from 0 to 1 or from 1 to 0) in the code and a 1 in the data produces no change in the code. It does not mean that the NRZ code is merely inverted. The main advantage of NRZI is that it does not matter at what point in the transmission that one starts to decode, the subsequent data will be the same. The code signal actually sent to the modem and transmitted by an amateur packet TNC, is in NRZI format. On receive the TNC converts it back to NRZ format for the CPU to process. NRZI is also known as NRZ-S (space).

National Traffic System. A volunteer amateur radio system for handling formal traffic messages, traditionally by CW but increasingly by packet and other digital modes in recent years. NTS had its origins in the very beginning of the ARRL (Relay meant relay of messages, not unlike todays forwarding of messages through the BBS system).

null modem
A interconnect device or data cable used to connect together two DCE or two DTE digital devices. The RS-232 TXData/RXData and RTS/CTS lines are swapped.

obsolescence count
In a NETROM/TheNET system, each node entry in the nodes table is given an "initial obsolescence count" each time the route is confirmed by a neighbor's node broadcast. The obsolescence count is reduced at regular intervals. When the obsolescence count reaches a predetermined value, the node entry is considered obsolete and is no longer broadcast to its neighbors.

An eight port diode matrix card once marketed by NEDA. For technical reasons (it loaded the RS-232 too much) it was replaced by the Hexipus board. See diode matrix, hexipus.

Ontario Packet Experimenters Network. For more information see TPG or HEX9. Also Ohio Packet Experimenters Network.

Open Systems Interconnect. A project of the ISO to develop a set of computer communication protocols.

The non-information data that is sent on a channel to control routing, addresses and supervisory bytes sent with the information data in the packet and any other transmissions that do not convey actual information but still take up time and capacity on the channel. Some node protocols (like ROSE) have less overhead than others (like TheNET).

PacComm Packet Radio Systems Inc. PacComm designs, manufactures and markets a range of packet radio products, both amateur and commercial, including the popular Tiny-2 TNC used in many network nodes.

A packet is a block of many characters (or bytes) which are sent together, along with a few extra characters (checksum) used to guarantee that the data is completely error free. The packet includes addressing information so that the receiving station knows that the packet is for it as well as who sent the packet.
A typical ham radio packet is:
lead-in flag bits - sent as a repeating series of 1-0-1-0-1-0-1-0 etc..
Address block containing a from-address and a to-address
flag bits separating address block from information frame
checksum consisting of a cyclic redundancy check number which is used to verify that the entire message is intact.
A packet will be ignored, as if it were noise, if the entire message is not received intact.
See also datagram, frame, information frame.

packet switch
Another name for a L3/L4 node. See also node, ROSE, NET/ROM, TheNET, BPQ.

A proprietary software from Pavillion Software. It creates a speciallized BBS for DXers and operates with all users connected in such a way that dx information can be distributed in "real time".

An advanced high speed network node controller designed and marketed by Gracilus Inc. The PacketTen controller will handle up to 10 ports, some of which can be up to 1 Mbps (that one million bits per second) and runs TCP/IP NOS code.

An amateur radio satellite carrying a packet store-and-forward node. When launched became OSCAR 16. OSCAR 19 (LUSAT built by AMSAT Argentina) is almost identical.

PACket Teleprinting On Radio. An HF digital communications protocol developed in Germany. PACTOR combines the good features of both AMTOR and packet for improved, more efficient HF data communications. There are two basic versions of PACTOR, the original German system that uses a unique form of analog bit addition method of forward error correction (FEC) and "digital" PACTOR that uses software to attempt to emulate the FEC system. The analog FEC is much superior but requires the use of a special PACTOR controller whereas the digital PACTOR can be run on a regular multi-mode TNC but requires a much higher signal- to-noise ratio to receive correctly.

Packet Assembler/Disassembler. A device that interfaces an ordinary "dumb" terminal to an X.25 packet network. It gathers typed characters into outgoing packets and translates incoming packets back into serial asynchronous data streams. Also provides a simple command interpreter for setting up and tearing down connections, controlling parameters, etc. The amateur packet radio TNC was heavily modeled on the PAD.

A terminal program written by Tony VK2DHU. See also Lan-link, Yapp.

AEA's name for their personal BBS in a TNC.

AEA's PK-232 multi-mode TNC.

The various timers, counters and other variables that control the operation of TheNET and similar nodes are called the node parameters. The node-ops use these parameters to manage the network and maintain efficient transfer of packets between the various nodes in a network. For more information on node parameters, contact your local node-op or network co-ordinator.

A bit added to a binary word for error checking purposes. For odd parity, a 1 or 0 bit is added to 7 data bits so that the total bit count is an odd number. For even parity, the total bit count is made even with the parity bit. Parity words can be similarly used with groups of binary words.

See parameters.

The path is the designated route through nodes, digis, and servers that must be used to pass data from one point to another. On a BBS message, the path is the list of BBS's thru which that message passed from origin to destination.

A PBBS can mean either a Packet Bulletin Board System (a normal full service BBS) or a Personal BBS. A personal BBS would better be referred to as a personal mailbox, maildrop, PMS or other such name to distinguish it from the full service PBBS. See also BBS, MSYS, FBBS, REBBS, RLIBBS, personal bbs.

Personal Computer Packet Adapter. A PC plug-in card made and marketed by DRSI that operates as a TNC.

In a NETROM/TheNET system, the technique of network management by "locking routes" and "locking nodes"is called perming.

A collision avoidance technique where the decision to transmit a packet is made by generating a random number between 0 and 255, comparing it to a parameter called p-persistance and if the random number is less than the p-persistance parameter, the packet is sent. If the number is greater, the TNC waits a period of time called slottime and then repeats the process. The p-persistance parameter is usually set to a value equal to 256 divided by one less than the maximum number of stations expected on the channel. See also Frack, Dwait, slottime, collision avoidance, back-off.

personal bbs
A limited function BBS contained within a users TNC firmware with which the user can enter or receive his/her own personal messages from other users or from the nearest full service BBS. Usually referred to by one of the commercial trade names such as PMS, Mail Drop, etc.

Protocol ID. The first byte of the packet frame which identifies which protocol is used for the packet frame. AX.25 PID is $F0 while TheNET and other higher level protocols have other PIDs.

Packet InterNet Groper. A TCP/IP diagnostic procedure that checks if another station is on the air and what the quality of the link is.

Phase Modulation. A modulation technique in which the phase of the carrier is shifted in direct relation to the modulating signal. Phase modulation is actually the modulation used in most so called "FM" radios used for voice communications. Phase modulation in which the modulating waveform has been de-emphasized by 6db per octive yields a signal identical to FM modulation. See also FM.

Poor Man's Packet. A simple modem and software package to be used with a personal computer to emulate a TNC. Developed by Andy N8KE and Kevin WB2EMS and published in 73 Magazine Aug 91. More info available from Kevin Feeney, WB2EMS. See also Baycom.

Personal Message System. PacComm's name for their version of a personal bbs in a TNC.

point‑to‑point link
Also called a dedicated link or a dedicated point‑to‑point link.
A radio link between two stations where both stations are configured such that they only hear each other, and where the parameters at each end of the link are optimized for that one other station. Point to point links may use directional antennas, unusual polarizations, finely tuned power levels, and other features to minimize bit errors, maximize throughput, and minimize the coverage footprint of the two stations, promoting best conservation of spectrum. See also dedicated links, backbone, shared multi-point link, HTS.

poll packet
In the latest version of AX.25 packet protocol, if a transmitted information packet is not acknowledged, the transmitting TNC will generate a poll packet to see if the destination TNC is still around. If the poll packet is acknowledged, then the transmitting TNC will once again attempt to send the information packet. Note that if there is periodic noise at the receive TNC, than the poll packets might be received but a particularly long information packet might never get through. In that case, the retry process might take place until timeout occurs and the link is disconnected. See also retry.

In packet terms, polling is a collision avoidance method in which one master station queries each of the users on the channel if they have a packet to transmit. The sending stations will not transmit until they have been "polled" by the master station. In this way no two stations will transmit at the same time thus avoiding collisions.

Post Office Protocol. A TCP/IP server that acts as a temporary storage of messages for stations that are not on the air continuously. Does not have the full functions of a BBS.

An input/output channel or connector on a node or TNC. A TNC normally has one or more radio ports hooked to a radio transceivers(s) and a RS-232 or serial port that may be connected to the users terminal (computer) or another node serial port in the case of a TheNET (or other type of higher level node) node stack. A port may also refer to a special purpose node such as a user-port, IP-port, backbone port, etc or any such access node to a network.

Short for potentiometer.

In its simplest form this is a variable resistor. Literally this is a device for changing the potential of a circuit. Abbreviated "pot", this is used for adjusting volume levels, regulated voltage, maximum current, transmit duration, lag time, or some other value. Electrically a potentiometer will change the resistance between one pin in the device (base) to two other pins (high and low). The resistance between the high and low pins stays the same while the base pin moves across the resistance range between the other two pins. Thus if the high to low resistance is 10Kohms, and the base is pointed just below the middle, you may get 4.7Kohms from base to low and 5.3Kohms from base to high. At the same time the low to high resistance will remain 10Kohms. This would be called a linear potentiometer. Another kind is a logarithmic potentiometer where the position of the base affects the resistance from base to low exponentially as the base is rotated toward high.

Potentiometers may be naked on a circuit board, or may be physically attached to a front panel and connected to a circuit with insulated wires. Potentiometers always have some means of making an adjustment, usually a knob or a screw-driver socket.

In the image to the right, R7 is a potentiometer. Inserting a screwdriver into the top of the yellow area will enable the operator to adjust the potentimeter. This particular unit turns for about 90% of a full rotation. Some units turn for many rotations from stop to stop and that kind of potentiometer is called a multi-turn.


A product of Anderson.

Anderson Powerpole is a quick disconnect used by ham radio operators to carry 12v DC. Powerpoles are delivered in single pin and dual pin variety though the dual pin is a recent adaption and is only available in red and black paired connectors. Multi-pin connections are assembled by fitting single pin connectors together. The pins have a most excellent spring loaded contact when the connectors are plugged together. They are also sex-less. Any pin will connect to any pin. If two or more pins are assembled into a connector arrangement, the pin systems become polarized while still being unisex.
Powerpole connectors are available in a variety of sizes. The 15A, 30A and 45A use the same plastic shell and the three current carrying sizes are able to be plugged together. Be sure never to plug a 45A load into a 15 or 30A current connector or wire!

A loosely organized group of sysops and node-ops in Quebec.

Packet Radio.


Same as commercial-means. This is any service that is run by people who are paid to run them. That means Internet, cellular networks, corporate links, corporate satellites, state radio, state microwave, state fiber, dark fiber, and anything else some ham doesn't personally maintain at their whim. Amateur radio managed hardware that is locked behind a door or gate is a grey area that we have to be really careful about because in times of emergency, we can't get to them to fix them. At least we can understand them and repurpose them.

Programmable Read Only Memory. A memory IC in which the data is permanently stored and cannot be altered. The term PROM actually covers both erasable PROMs such as EPROM and EEPROM and non-erasable proms programmed by blowing fusable links or diodes on the chip. In practice however PROM usually refers only to the non-erasable types. See also EPROM, ROM. protected backbone = A protected backbone is a channel where none of the known nodes involved on the backbone will accept traffic from any unknown device on the channel.

A communications protocol is the set of rules and procedures used to implement a technique or method of communications.

pseudo-digital repeater
A full duplex node or repeater which transmits a signal (such as a tone, flags or unmodulated rf carrier) to indicate to the other stations on the channel that the channel is in use. An example would be a HAPN 4800 bps node that transmitted a carrier whenever an rf signal was heard on the input channel. As the HAPN DCD is actually a noise squelch system, the presence of such a carrier on the input of the node is "repeated" to the output channel. This can be very useful on split frequency multiuser shared channels. It is also simpler than a full regenerating repeater but at the cost of half the throughput. An audio repeater used in packet service would be a pseudo-digital repeater if the repeated tones were unsuitable for decoded data (say due to phase shift or noise) but served to prevent collisions.

Phase Shift Keying. A data modulation method in which binary data is encoded as discrete changes in the phase of the carrier signal. In amateur packet, PSK is used mainly on OSCAR satellite data communications. PacComm markets a PSK modem to be used with TNCs.

Packet Status Register, a newsletter published by Tucson Amateur Packet Radio Corp. See TAPR.


Reported to be a program for satellite downlink telemetry.

Public Domain
Available to the general public at no charge. Information, especially computer programs, that are released for unrestricted use by anyone are said to be in the public domain. Such programs are also called freeware. See also shareware, freeware, hamware.

Man-made interference on a radio frequency, whether intentional or not. Ignition noise would be a good example of QRM that can affect packet signals since a single pulse could possibly alter a bit and therefore destroy a packet.

Natural interference on a radio frequency such as lightning crashes, rain or snow static or solar noise.

NETROM/TheNET software allows for a factor called quality to distinguish between various paths joining two nodes. The quality factor is used to select the "best" path for a connection between the two nodes. The quality assigned to each path is determined by initial values set by the node sysop and was originally intended to indicate the relative communications efficiency of each path. More recently however, quality has been used as a route management tool by the node and network sysops and would probably be better named the "route priority factor".

Radix 85. See B2A/A2B.

Radix 95 is a shareware program written by Greg WD5IVD and distributed by Texas Packet Software. A communications protocol for sending binary data on packet by converting it to ASCII by a known algorithm, splitting the file into small chunks and sending them as regular messages. See also 7-Plus, conversion program.

Random Access Memory. The volatile memory IC in a computer that holds data only so long as power is applied. A TNC uses RAM for temporary storage, messages and parameters. This may be made non-volatile with the use of a lithium backup battery. There are two types of RAM, SRAM (static RAM) that will retain data as long as power is applied and DRAM (dynamic RAM) in which the data must be renewed periodically to be retained without loss.

Raspberry PI
A computer designed by the charity, Raspberry PI Foundation in Great Britain, as an educational tool. The Raspberry PI has sold millions of units. There is an A version unit and a B version unit. The Foundation started taking orders for the B unit in Feb 2012 and the lower cost A unit a year later. Model B has 512MB SDRAM, two USB ports plus Ethernet. The A unit has 256MB SDRAM, no Ethernet and only one USB. The two units use the same CPU and graphics.

The Radio Amateur Telecommunications Society. RATS is an amateur radio association in New Jersey that is dedicated to the improvement of communications systems in the Amateur Radio Service. RATS is best known in the packet field for ROSE, a networking protocol software written by Tom W2VY and others. For more information on RATS contact: The Radio Amateur Telecommunications Society, P.O.Box 93, Park Ridge, NJ 07656-0093. See also ROSE, ROServer, PRMBS.

Real-time in packet terms may have several meanings. A real-time repeater transmits the received data at EXACTLY the same time (not counting the phase shift or circuit delay of a fraction of a millisecond) as opposed to a node or digi-peater which will delay repeating the data until the channel is clear (known as store-and-forward). Real-time may also apply to a keyboard-to-keyboard contact in which the data exchange delay does not exceed the users attention span. Non-real-time could refer to a BBS message that could take hours or days to be exchanged.

An amateur BBS software written by Roy AA4RE. Also 4RE BBS.

A BBS server program written by Chris, G6FCI. REDIST is designed to allow users to send a personal message to a BBS in a distant part of the world and have it converted to a limited coverage bulletin for distribution in that locality. It is written for and can only be used on a FBB BBS. Also a REDIST program having the same function has been written by Hank, WRLI for use with the RLIBBS system.

redundancy path
An alternate path between 2 nodes on a network that can be used if the primary path fails for whatever reason.

regenerating repeater
See repeater, full duplex real-time regenerating.

remote host
A remote host is the computer at the other end of a TCP/IP host to host link. See also host, TCP/IP.

repeater, full duplex real time regenerating
A digital repeater that receives and transmits at the same time (on 2 separate frequencies). The received and demodulated data is fed to the transmitter modulator so that an exact copy of the received data (but cleaned of all noise and distortion from the receiver) is retransmitted at the same time it was received. Such repeaters are useful to create a hidden transmitter free environment on a wide area network. See also digipeater, real-time, pseudo-repeater.

response time
This is the time between sending data to a remote device before an expected response returns to the originating station. Also in the ax.25 protocol, response time is the deliberate delay after a frame is received before the ACK frame is sent so that the ack frame may be piggy-backed on an outgoing data frame if possible.

Retry is the process by which a packet that is sent and not acknowledged will be resent by the sending station. This retry is repeated until the acknowledgement is received or until a "retry counter" reaches its limit and the circuit is terminated. See also back-off, dwait, frack, persistance, collision avoidance.

reverse forward
Reverse forward is a process where a connecting BBS may request if any mail is available to be taken by the connecting BBS at this time.

Registered Jack #12. This is a connector used for microphone plugs on many different mobile radios.

The RJ-12 connector has 6 conductors.

Registered Jack #45. This is the connector used on Ethernet wire and for microphone plugs on many different mobile radios.

A RJ-45 connector has 8 conductors.

The RJ-45 connector is commonly used for 10baseT and 100baseT Ethernet. It is often seen with CAT5, CAT5e and CAT6 wire.

Shown to the right are three views of a shrouded RJ-45 plug. The shroud is the blue plastic cover which protects the release clip.


An amateur BBS software package written by Hank WRLI.

Reference Model. Another name for the OSI 7 level set of data communication protocols. See also OSI, ISO.

Read Only Memory. A non-volatile memory IC used to permanently store operating programs in computers and other digital devices. ROMs come in many forms such as masked ROM (permanently programmed by the IC manufacturer), PROM (field Programmable ROM), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), OTP (One Time Programmable ROM), etc.

ROM image
The set of binary data that is programmed into an EPROM or other ROM.

RATS Open Systems Environment. A networking protocol software written by Tom W2VY and others from the Radio Amateur Telecommunications Society in New Jersey. It is distinguished from other network protocols such as NET/ROM and TheNET in that the routing tables are manually maintained rather that being automatically set-up and updated as with NET/ROM and TheNET. This results in less overhead on the network since routing information does not have to be broadcast regularly. From the user standpoint, ROSE requires only that you know the ROSE address (derived from telephone area codes and exchange numbers) of the destination node and callsign. For more information on the ROSE protocol, see the downloadable user information files on many BBSs or contact RATS directly. See also RATS, TheNET.

An amateur packet BBS software written by Brian KA2BQE. Although PRMBS was written originally for use on the ROSE network, it is now being used on many non-ROSE systems. See also BBS, ROSE, RATS.

Route stepping
See Node hopping.

Any device that can control and direct the routing of datagrams by a node. For example the internal protocol in TheNET X1-J firmware that directs IP datagrams to their proper address according to a manually entered routing table would be an "IP router". See also dynamic routing, Net/ROM.

routing loop
This is a condition where a packet is sent through a node more than once due to routing errors. This can usually occur when one node in a NETROM/TheNET network fails and some of the remaining nodes continue to broadcast its existance for several hours but with unusable routes.

RS-232-C is the Electronics Industry Association (EIA) standard number for the most common interface used between computers. RS-232 data is sent 1 bit at a time with a negative voltage (called MARK) to indicate a zero value and a positive voltage (called SPACE) to indicate a 1 value. Additional bits may be added to separate the characters being sent. Also called serial communications. RS-232 is an asynchronous communications protocol.

Ready To Send. A control line on a RS-232 port that indicates that the device has data ready to send. On some devices the DTR line is used instead of RTS. On a packet TNC modem header, the RTS line is used as PTT signal for the transmitter. See also CTS, DTR, RS-232, handshaking.

Radio TeleTYpewriting. An early mechnical based (now replaced by computers) method of data communication on radio using the 5 bit baudot code. In 1980 8 bit ASCII was also permitted on RTTY in the US. TELEX and TWX are commercial telephone systems using the same techniques as RTTY.

Regenerativer Umsetzer fur Digitale Amateurfunk Kommunikation (English = Regenerating Transponder for Digital Amateur Communications). A packet transponder project flown on board OSCAR 13 satellite. Developed by AMSAT-DL group in Germany.

Received Data stream produced by a modem demodulator. See also TXData.

Shuttle Amateur Radio EXperiment. An educational program in which U.S. Shuttle astronauts communicate with schools using voice and packet.

A communications system that is full duplex at one end and simplex at the other end. Packet operation through a realtime full-duplex repeater would be semi-deplex operation.

serial port
The RS-232 serial asynchronous communications Input/Output port on a data device such as a computer or TNC.

serial communications
Digital communications in which the data is sent one bit after another on a single wire or or radio link. See also asynchronous, synchronous.

server, server node
A server is any station that provides a service to users other than the owner. This may include BBSs, DxClusters, DOSgates, TheNET nodes, ROSE nodes, TCP/IP hosts, Callbook lookup, HF gateways, etc. Servers are usually distinguished by being large generators of data on the network.

shared, HTS free backbone circuit
A backbone channel shared by 3 or more nodes, all of whom can hear each other either directly on a simplex frequency or with the help of a digital repeater (regenerating or pseudo- repeater) on a full duplex split frequency. The available throughput on the channel is shared between the users and appropriate persistance and slot-time must be used. See also backbone, HTS, repeater, collision avoidance, persistance.

Computer programs that are DISTRIBUTED freely and may be copied by anyone and evaluated free of charge but for which serious users are expected and requested to register and pay a user registration fee. Those who do register the program usually obtain additional documentation, updates, etc as a reward.

System ID. A block of characters exchanged between BBSs when they connect to each other. The SID is used to indicate which software system the BBS is running and what features are available for forwarding.

A communication method in which communication between two stations takes place one direction at a time regardless of whether the receiving and transmitting is on the same frequency or on split frequency. However in amateur radio terminology, simplex usually means receiving and transmitting on the same frequency. This can lead to confusion, so one should be very precise as to what they mean when referring to simplex (either single frequency simplex or split frequency simplex). Amateur packet operation is normally simplex but most modern TNCs are capable of operating full-duplex if connected to the proper radio system. See also half-duplex, full duplex.

shield card
a daughter card for one of the tiny computers like Arduino or Raspberry PI. The daughter card in this case is usually the same size as the computer board so it completely obscures the top of the computer. It may be called a shield because it protects the motherboard from visibility.

simplex digipeater
a regenerative digital repeater that receives a packet, verifies that it was received correctly, and if appropriate retransmits it on the same frequency it was received on as soon as the channel is clear. Also called a Store-and-forward repeater. Compare with: Repeater, Full duplex real time regenerative, which retransmits the data at exactly the same time as it was received but which does not check for errors. See also digi, duplex digipeater, repeater, store-and-forward.

site hardening
Term for ruggedizing a site by adding backup power, shielding or lightning protection.

site manager
Person(s) who is responsible for node and repeater site access and hardware maintenance.

site sponsor
This is the person or group who is financially involved in acquiring and maintaining node hardware.

site sysop
This is the person(s) who is responsible for the software and configuration of a node site. Also called a node-op or node sysop.

SImplex Teleprinting Over Radio. A commercial communications system very similar to AMTOR and used mainly for marine communications.

slime trail
On a NETROM/TheNET node, the node table will temporarily show distant nodes that connect through it. The temporary node will be listed at the beginning of the nodes list and will show callsigns only, no alias. This node list entry is called a slime trail because you can trace back to see the origin and route of the distant node.


In the persistance method of collision avoidance, slottime is the time delay before repeating the random number persistance calculation. See also persistance, Dwait, CSMA/CA, collision avoidance.

Simple Mail Transfer Protocol. This is the part of the TCP/IP system which is responsible for sending mail between TCP/IP hosts.

Slang term meaning installed/in-use software that was not free, and was not paid for, i.e. was stolen.

SuperPacket. It is a packet terminal program written by Sigi DL1MEN of the Baycom team in Germany. The latest versions (since ver 7.0) are NOT public domain software and must be purchased from the author.

Space, like mark, is one of the two possible states in a binary communications system. On an asynchronous serial system, the start bit is space. On a RS-232 port, the positive voltage level is space.

A DX information message posted on a PacketCluster. A spot usually contains the frequency and callsign of a dx station presently on the air with the call of the station entering the info.

Secondary Station IDentification. A number (from 0 to 15) added to a callsign when a packet user needs more than one packet address. For example, VE2RM-0, VE2RM-4, VE2RM-7, etc are different packet addresses for the various TNCs used at the VE2RM node site. Or a user station may use a different SSID for his personal mailbox bbs and for his keyboard operations.

Special Temporary Authorization. In the USA, a special permit granted by the FCC to operate in a manner not normally permitted. ALL AUTOMATIC HF packet forwarding up to 1993 was permitted under a small number of STAs sponsored by ARRL even though unattended HF operation was not normally permitted.

The process used in nodes and digipeaters where a packet is received, processed for errors, ect, and retransmitted toward its destination at a later time (seconds later). This is compared with a full duplex digital repeater that retransmits the data at virtually the same time. The term may also describe the BBS forwarding of messages hours or even days after they are entered or received.

When multiple connections are made from the same TNC at the same time, each connection is called a stream.

Another name for a node. See also packet switch, node, ROSE, BPQ, NET/ROM, TheNET.

A serial communications mode in which the data bits are sent continuously without character start and stop bits and with an embedded clocking signal for synchronization of the receive circuits. Amateur AX.25 packet radio communications use synchronous transmission of data.

sysop, BBS sysop
The person(s) responsible for the smooth operation of a BBS, including maintaining forwarding routes, redirecting misaddressed messages, checking for illegal or improper messages, etc. See also site sysop, BBS.

Tucson Amateur Packet Radio Corp. TAPR is a non-profit organization that develops and promotes amateur packet radio including hardware, standards and publications. TAPR is probably best known for the TNC-2 TNCs (and their widely marketed clones) that were the impetus for the major growth of amateur packet radio. They publish a regular newsletter called Packet Status Register (PSR). For more information on TAPR please contact: Tucson Amateur Packet Radio, P.O.Box 12925, Tucson AZ 85732-2925.

Terrestrial Amateur Radio Packet Network
Two definitions
1. A packet radio network built entirely of Amateur owned operated radio equipment and forsaking any automated trafficking to or from commercial professionally operated networks like the Internet.
2. A group founded by KA2DEW and located mostly in the vicinity of Raleigh/Durham/Chapel Hill North Carolina which is fostering a TARPN.

Transmission Control Protocol. A major element of the ARPA suite. Provides reliable, connection-oriented byte stream service on an end-to-end basis. Runs atop IP and sits at the transport and session layers. See also KA9G, TCP/IP.

In amateur packet, TCP/IP refers to the KA9Q Internet software or any of its many versions running on a personal computer. It also refers to any of the servers such as JNOS running on the network under TCP/IP control.

A presentation/applications protocol in the ARPA suite used for terminal to terminal and terminal to host communications (e.g., remote login). This protocol is used in Packet/Internet gateways to allow connections with other similar gateways around the world.

Two definitions:
1. A network site with only one link. An end of the network.
2. Any data display/data entry device. A terminal usually consists of a CRT (cathode Ray Tube) display and a keyboard connected to a RS-232 serial port. May also be called a dumb terminal because it cannot do any computational operations.

A networking node protocol developed by the Texas Packet Radio Society Inc. and used primarily in Texas and the southwest.
Also, a network in Texas built by the Texas Packet Radio Society using TEXNET equipment. TEXNET the network appears to have gone away around 2000.

A program written by the Nord<>Link group in Germany that emulates WA8DED Host firmware in a PC.

A driver program developed by the Baycom group in Germany for Baycom and USCC cards when used with SP and GP terminal programs. See also Baycom, GP, SP.

A TNC based node program developed by Hans DF2AU and the Nord-Link group in Germany. TheNET node firmware runs in a TNC. It presents a connection point in a network enabling a station to connect into the network. The user is then presented with a command syntax that enables connection to another TheNET node or to connect out of the network to a service or user station.
TheNET resembles NET/ROM and there is some dispute as to who was the originator. TheNET is public domain software and has been expanded on by several other groups, for example, TheNET 2.xx from Bill NJ7P and others in Arizona and TheNET X1.x from Dave G8KBB in England.
TheNET uses an automatic adaptive routing protocol to set-up and maintain a routing table for the proper transfer of packets to neighboring nodes according to node information received from neighboring nodes on a regular basis. As with any L4 transport layer node, it accepts responsibility for the delivery of the packet to the next L4 node along the path and acknowledges back to the sender the correct reception of the packet. See also NET/ROM, BPQ, TCP/IP, ROSE, NOS, Converse node. Compare with: ROSE node which uses manual maintenance of the routing tables. Compare with: Digipeater, which does not acknowledge to the sender, does not take responsibility for delivery and can only relay a packet to the next digi along the path.

TheNET Plus
TheNET 2.xx versions written by Bill NJ7P.

The amount of data sent by an originating station that actually reaches its destination in a given period of time. This must not be confused with the channel data rate in baud or bps. Throughput can be calculated either by observation or by taking the original data rate and subtracting out all the wasted time and overhead due to network protocols and TX delays, lost time due to choking and that due to collisions. See also choke, overhead, retries, response time.

Tigertronics Inc. markets a Baycom modem called Baypac and is an official distributor of Baycom ver 1.5 software. See Baycom.

In a NETROM/TheNET network, all frames are assigned a Time-to-Live number which specifies the maximum number of nodes the frame can be passed to before being cancelled. It is used as a protection against looping endlessly or to control the propagation of L4 routes.

Slang for TNC.

A compact TNC manufactured and marketed by PacComm. The Tiny-2 is fully compatable with all TNC2 firmware and is very popular for node operation. The latest version (Tiny-2 Mk2) accommadates 2 different firmware programs that may be switched at will. See also PacComm.

Terminal Node Controller.
A TNC is a box created for use by end-user stations as a stand alone computing platform. A ham operator with a dumb terminal could use a TNC to receive and transmit packet radio. TNCs were invented in the early 80s and generally operate with a simplex radio to establish connections via other trivial packet radio equipment.
TNCs can serve as building blocks of more sophisticated networking hardware by using computer accessible protocols into and out of what was the ham-operator end of the TNC.
A TNC is a computer interface to a dumb terminal, or to a real external computer, with a packet assembler/disassembler. The packet assembler/disassembler takes the message components from the computer interface, and sends it over the radio, having pursued its own timing in concert with channel activity. It may also receive a packet message from the radio and make it available to the computer interface. The timing of the transmit and receive operations is notionally under the control of the computer interface but it is actually capable of receiving a message even as the computer interface is asking it to transmit.

In 1984 TAPR released their second model TNC which used a Z-80 CPU instead of the 6800 CPU used in the original TAPR TNC. The TNC had a few interesting features, some of which were very important to the development of packet radio capability in the next 20 years.

TAPR later released a 2nd model of the TNC-2. This one came with the larger memory complement and one more LED on the front.

TNC-2 clone
TAPR licensed the TNC-1 and TNC-2 designs. The TNC-1 begat the Kantronics TNC line. TNC-2 begat MFJ, PacComm, DRSI and a few others.

See TNC-2

A TNC manufactured by Coastal Chipworks and designed to work piggyback on a Raspberry PI board. The TNC-PI uses an I2C interface to support multiple TNCs on the same Raspberry PI.

The TNC-PI uses a Microchip PIC CPU and supports KISS mode only. It does not digipeat, make or accept connections without support from a host computer.

A TNC manufactured by Coastal Chipworks. This TNC includes USB connection to the host computer (if any). The TNC uses a Microchip PIC CPU.

token ring
This is a system where multiple stations share a LAN and maintain a permission slip (the token) which grants transmission authority to one station. That station would finish its transmit one-way, or exchange, and then grant the token to another station on the LAN.

topology (network)
The study of or the description of the hardware configuration of a network with all its nodes, links and paths. How well a network functions is more related to its topology than to the software used to form a network.

Toronto Packet Group. An active packet radio group in Toronto, ON. For more information, contact Keith Goobie VE3OY @ VE3OY.

An amateur packet terminal program for personal computers written by Gerard FC1EBN and others. TPK is designed to run in conjunction with a complementary program on a FBB BBS to give the user an up-to-date listing of BBS messages without having to connect to the BBS. The FBB BBS sends out a UI frame with the header information each time it receives a message or bulletin. The user station monitors the channel in an unconnected mode and records the UI frames so as to prepare a listing of the bulletins available. Any personal messages and any desired bulletins can then be downloaded by the user terminal automatically (often using compressed forwarding). This technique is designed to reduce congestion on the channel where normally many users would connect and download the same long list. See also FBB BBS.

transfer rate
See data rate.

transparent mode
A mode of operation of a packet TNC that allows the sending of all possible binary sequences without fear of actuating commands in the TNC. Designed for the transfer of binary data files. See also converse mode.

transport layer
Level 4 protocol in the seven level OSI computer communications protocol set. It controls the transfer of datagrams between two level 3 nodes via a number of intervening L3 nodes.

Transistor Transistor Logic, or Time To Live.
Transistor Transistor Logic is The name for one of the types of circuitry (made up of bipolar transistors) used inside TNCs, computers and other digital circuits that operates on logic voltage levels of 5v and 0v. This compares with the serial port RS-232 voltage levels of -12v and +12v. Some TNCs have a TTL level plug to interface with simple computers such as the Commodore C-64.
Time-to-Live is a figure sent in a packet transmission which determines how many radio hops a message is allowed to transit. On each hop the TTL figure is decremented. When it reaches 0, the message will not be repeated again.
Time-To-Live is used to mean a decrementing counter in other networking discussions.

turnaround time
The total time that it takes for a radio and TNC to switch between transmit or receive so as to properly communicate with the other end of the circuit. See also TX Delay.

Transmit Data stream fed to a modem modulator. See also RXData.

The delay between the time the TNC issues a transmit command and the actual packet data starts. The TNC usually sends flags during this period although some node software may send an alternating 0101 bit stream that sounds to the ear like a pure tone.

Unnumbered Acknowledgement frame. A packet frame sent in an unconnected mode to acknowledge a connect or disconnect request.

Universal Asynchronous Receiver/Transmitter. This is an IC used in computer devices to convert high speed parallel data from the CPU data bus into a lower speed serial data stream for the RS-232 interface.

Unnumbered information frame. An Information frame without a frame number that is sent as a broadcast during a beacon, nodes broadcast, CQ, TPK item, and other similar frames. It is not acknowledged and there is no guarantee that it will be received. Also called an unproto packet.

An unproto packet is another name for a UI frame.

A circuit from a user to a node or BBS initiated by the user. See also downlink.

The process of transfering data from a user station to a BBS or server. Usually refers to sending messages or large files from a user to a BBS.

Packet networking software written by N1URO. The software uses Linux drivers and tools and provides compatibility with TCP/IP and many modern and legacy HF and VHF packet radio protocols. It also provides interoperability with many modern packet over Internet tools. http://n1uro.ampr.org ftp://n1uro.ampr.org/packet/

An internal PC packet modem card.

user port or user channel
This would be a mechanism for a transient station to access the network without making prior arrangements. This would be either a zoo channel where collisions could occur, or would be a DAMA, token ring, or other controlled collision free system where stations could check in to the network and then be given a slot, or be polled, to participate. The software/firmware required to operate the user station is not common.
See also LAN, DAMA, polling.

A binary to ASCII text conversion program and file transfer protocol originally written for Unix to Unix (uu) data transfers over 7 bit links. See also conversion program, R95, 7-Plus.

Vancouver Amateur Digital Communications Group. An amateur packet group in Vancouver B.C. responsible for developing one of the earliest widely used packet protocols called the Vancouver Protocol.

vancouver protocol
An amateur packet level 2 protocol developed in 1979 by Doug VE7APU and VADCG in Vancouver BC. Also known as the VADCG protocol.

See virtual circuit.

virtual circuit
The service provided by a connection-oriented network. Virtual circuit data packets generally carry less header information than datagrams, since addresses have been specified at connection setup time. Amateur packet AX.25 level 2 uses virtual circuits. See also connection-oriented.

Ronald Rakes, WA8DED wrote and released firmware for the TAPR TNC-1 and later the TAPR TNC-2 which fully implemented the TNC operation. The big difference between DED code and the TAPR original was that the computer to TNC interface was more easily operated by an application on the computer. DED firmware was adopted by BBS application developers as the TNC code of choice.
Ron's source code was released into the public domain and this also enhanced the respect his programs had in the community.
NORDLINK, a German packet radio group and DC4OX wrote a TNC package called TheNET which utilized WA8DED's source code and was itself released as open source. This became the parent of many other networking packages including G8BPQ, NET/ROM, MSYS etc..
See also Host mode.

See wide area network.

weather node
A weather station linked to a packet radio node for remote monitoring of weather conditions by packet radio.

wide area network
A data network covering a large geographical area often linking together many LANs on the same channel. A good (or poor depending on your viewpoint) example of a wide area network is the 145.01 MHz channel used on 2m 1200 bps packet. Wide area networks are also chronically affected by severe hidden transmitter syndrome (HTS) and exposed receiver syndrome (ERS). See also HTS, LAN, ERS. Compare with: LAN which covers a small area and which ideally should have only one node or server on the channel.

wideband packet
Anything faster than 1200 bps (baud). Some would suggest that anything slower than 56Kbps is not wideband or that wideband would be any speed that requires more radio bandwidth than the "normal" VHF fm transceiver used on amateur packet.

A Windows based packet terminal program written by Howard KI7CU. WinPak (latest version 1.50) is in the public domain as "Hamware" free to all radio amateurs.

This is a slang name for a Personal Computer using an Intel processor 80386 descendent processor and capable of running MSWindows. Wintels run Linux as well as Microsoft OSs.

wireline link
A connection between the modem headers of two or more TNCs such that the TNCs communicate via their radio ports but without the internal modems or radios. This allows 2 diode matrices to be connected together to form a "dogbone" or allows two TNC's with different protocols (such as KANODES or ROSE nodes) to communicate with each other at high speed. The communication takes place using AX.25 protocol.

Another term to describe a node to node or TNC/node to PC server connection via the serial ports and a diode matrix if necessary.

Hank Orelson, W0RLI, author of a widely used packet bulletin board. See also RLIBBS, CBBS.

An amateur packet circuit between two distant points using commercial communication circuits such as Internet, telephone, satellite or microwave links.

A CCITT standard protocol for the subscriber interface to a public packet switched network. Consists of two layers, link (level 2) and packet (level 3). The amateur AX.25 protocol is a highly modified version of just the link later of X.25; it does not have a packet layer.

Software handshaking using characters such as Crtl-S/Crtl-Q to turn on and off a communications channel. Compare with: RTS/CTS handshaking which uses hardware control lines on the RS-232 port to control data flow.

Yet Another Packet Program. A shareware terminal software package to interface a personal computer to a TNC. Contains scrolling, message handling, editing, and other utilities to aid the user on packet. Also a protocol for transferring binary files over radio or telephone links. Written and supported by Jeff WA7MBL. See also Lan-Link, Paket.

Do not hesitate to verify any of this information and (as usual) send me corrections, missing words, better definitions etc.
Notes: This Glossary of Packet Terms has been compiled from several sources in the public domain in addition to my own personal knowledge and experience.
The following are listed as authors of this glossary:
VE2BMQ, KA2DEW, N2IRZ, Toronto Packet Group
North East Digital Association, Northwest Amateur Packet Radio Association,
TPG Packet Users Guide.
Copyright 2014↝2017 -- all rights reserved by KA2DEW. If reproduced, the reproduction must include an amended copy of these Notes. May not be reproduced in any form for commercial purposes with the express permission of all of the authors, living and dead. Amateur network groups (including but not limited to ham radio) may reproduce this document as part of a package for the purpose of promoting packet radio or their local network provided that full credit is giving to the source and authors. Any group intending to use this document for the approved purpose should contact the authors for the latest update version in HTML format.
Tadd, KA2DEW, care of TARPN.