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Publications:

ARRL 7th Computer Networking Conference 1988

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This proceeding is available on CD-ROM


Location:
Columbia, Maryland

Coordinators:
Tom Clark, W3IWI
Andre Kesteloot, N4ICK
Dave Tillman, WA4GUD
Jack Colson, W3TMZ
Paul L. Rinaldo, W4RI

Hosted by:
Johns Hopkins Applied Physics Laboratory ARC
Tucson Amateur Packet Radio Association (TAPR)
Amateur Radio Research and Development Corporation (AMRAD)
Radio Amateur Satellite Corporation (AMSAT)
American Radio Relay League (ARRL)

Abstracts:
7th Computer Networking Conference
October 1, 1988

A Duplex Packet Radio Repeater Approach to Layer One Efficiency. Part Two
by Scott Avent, N6BGW and Robert Finch, N6CXB
Abstract: Last year the authors presented the first part of this paper at the 6th conference by presenting related material NOT contained within the text of the published paper itself. The intent of the verbal presentation was to spur interest in reading the published paper itself. This presentation contained a simple mathematical examination of simplex versus duplex repeater approaches to local area network implementation. In contrast the paper contained the design goals and basic equipment approach we implemented in our duplex repeater environment here in Southern California.

Proceedings Paper



Formal Description in Estelle of AX.25
by Michel Barbeau, VE2BPM
Abstract: A protocol description must be precise as possible in order to avoid multiple subjective and incompatible interpretations by the different implementers. Natural language (e.g. English) descriptions are a priori easy to understand but they are i ngeneral ambiguous. It has been now recognized that formal techniques give rise to more precise and complete descriptions of software. Estelle is such a formal technique specially designed for communications protocols. This paper investigate the use of Estelle for describing AX.25 a link-level protocol for packet-radio.

Proceedings Paper



International Code Designator for Amateur Radio
by J. Gordon Beattie, Jr., N2DSY and Thomas A. Moulton
Abstract: Amateur Radio now has an International Code Designator (ICD) assigned by the International Organization for Standardization (ISO) to identify Amateur Radio organizations, network components and applications in Open Systems. Open Systems are defined by the* use of the communications protocols of ISO and the International Consultive Committee for Telephone and Telegraph (CCITT) and their national member bodies. The architecture has been defined by these bodies as a model called the Open Systems Interconnection Reference Model (OSI-RM) to facilitate communications between applications using different computers and operating systems.

Proceedings Paper



Amateur Framing Protocol
by J. Gordon Beattie, Jr., N2DSY, Terry Fox, WB4JFI, and Thomas A. Moulton, W2VY
Abstract: Over the last ten years Amateur Radio packet mode operations have evolved to the point where there are approximately fifty thousand Radio Amateurs worldwide using the AX.25 Link Layer Protocol implemented in special computer interfaces called Terminal Node Controllers (TNCs). During this period many functional extensions or changes to the protocol have been suggested, but their use would not conform to the basic AX.25 protocol.

The authors have identified a common set of protocol capabilities which can be provided in a simple framing sublayer. These capabilities include framing, station identification, bit-error detection, digipeating, and appiication specific options. The Amateur Framing Protocol (AFP) presented in this paper defines a a format and a set of rules to support these functions, while providing an envelope for higher layer protocols such as ARRL AX.25 Link Layer, CCITT Q.921, CCITT Q.931, CCITT X.25, ISO 8208, ISO IP, and US DoD TCP/IP and ARP.

Proceedings Paper



Amateur Framing Protocol Specification
by J. Gordon Beattie, Jr., N2DSY, Terry Fox, WB4JFI, and Thomas A. Moulton, W2VY
Abstract: The Amateur Framing Protocol (AFP) is a general purpose data format protocol for Amateur Radio packet mode communications systems. AFP provides the framework on which other protocols may be implemented. An AFP frame provides an envelope to support any form of Logical Link Control protocol which two (or more) stations wish to use during packet mode operations. The relationship of AFP to other protocols is shown below.

Proceedings Paper



A Routing Agent for TCP/IP: RFC 1058 Implemented for the KA9Q Internet Protocol Package
by Albert G. Broscius, N3FCT
Abstract: The KA9Q Intemet Protocol Package has introduced full TCP/IP internetworking to the Amateur packet community yet, until now, automatic routing has not been available within the package. This paper describes an implementation for the KA9Q package of the DDN Internet standard Routing Information Protocol as specified in RFC 1058. Proper usage and configuration of this routing code are explained.

Proceedings Paper



Recommended Power and Antenna Height Guidelines for LAN's and WAN's
by Bob Bruninga, WB4APR
Abstract: What follows is simply an appeal that we apply some degree of frequency coordination within the digital allocations on two meter FM. We have noted rapid growth in the nASH DC area as shown in figure 1 with over 38 BBS's, 35 DIGI's and a number of NET/ROMS and TCP/IP nodes spread over the 100 KHz segments starting at 145.0, 145.5 and 145.6 plus 221 MHz. The nature of packet radio i3 quite forgiving in accommodating multiple users and a mix of services on any one frequency. But condoning a total free- for-all mixture can not possibly result in an effecient network. The opposite extreme of total coordination and rule making is restrictive and abhored by most radio amateurs.

Proceedings Paper



A Totally Awesome High-Speed Packet Radio I/O Interface for the IBM PC XT/AT/386 and Macintosh II Computers
by Mike Chepponis, K3MC and Bernie Mans, AA4CG
Abstract: This paper describes a plug-in card for IBM PC XT/AT/386 compatible computers or the Apple Macintosh 11 computer. It is designed to handle two 56 kilobit/sec full-duplex channels via DMA and 10 slow speed (19,200 bits/sec or less) channels via interrupts without main processor intervention. The board uses an NEC V40 processor and up to six Zilog 85C30 Serial Communication Controllers, together with either 256k bytes of DRAM or 1 megabyte of DRAM to omoad the main processor from low-level interrupt fielding. It communicates with the main processor with an 8k byte memory window in the IBM version, and directly with Macintosh II main memory using the Bus Master concept of the NuBus. It is targeted at replacing existing TNCs in the high-speed networks of the future; special consideration has been given to the support of TCP/IP. Even the minimum (easily upgradable) implementation with only one 85C30 outperforms all existing TNCs, relying on the host PC only for bootstrapping, power, and of course, an effective user interface when called for.

Proceedings Paper



AMSAT's MICROSAT/PACSAT Program
by Tom Clark, W3IWI
Abstract: In 1989 AMSAT-NA plans to launch the first of a series of low-earth orbit (LEO) satellites dedicated to serving digital store-and-forward message handling. These satellites are quite small cubes, approximately 230 cm (9 inches) on a side weighing less than 10 kg this small size has led to our calling the project MICROSAT. Despite the small size, the satellites are crammed with state-of-the-art electronics. This paper will review the development program leading to this design and some of the technical details as well as describing how the terrestrial user will make use of the resource. We are planning on the launch of 4 satellites using MICROSAT tcchnology into LEO in early 1989, and several more launches over the next 2 years.

Proceedings Paper



The DSP Project Update
by Dr. Thomas Clark, W3IWI and Dr. Robert McGwier, N4HY
Abstract:TAPR and AMSAT have signed a formal agreement which forms a joint project. The purpose is to bring the rapidly advancing technology and techniques of digital signal pro- cessing to bear on the communication needs of amateur ra- dio. The AMSAT-TAPR digital signal processing project has made steady progress over the past year on both soft- ware and hardware. Lyle Johnson is leading the hardware effort in Tuscon and will report on that progress elsewhere in these proceedings. We will report on work that is on-going to choose what the second generation DSP unit will look like.

Proceedings Paper



Digital Radio Networks and Spectrum Management
by Paul A. Flaherty, N9FZX
Abstract: Spectrum Management is a vital part of amateur radio. Questions of where to place services in the available spectrum continue to plague frequency coordinators. This paper contends that multiaccess radio systems should be allocated in the spectrum below one GigaHertz, and that monoaccess or link oriented systems be placed above that frequency.

Proceedings Paper



Where is My High-Speed RF Part II
by Terry Fox, WB4JFI
Abstract: In 1986 this author presented a paper at the 5th ARRL Computer Networking Conference in Orlando, Florida regarding high-speed RF (or more accurately the lack of it). That paper was meant to spurn on experimentation in the RF arena of packet radio. This paper is meant to continue where that one left off. It seems we have made some progress, but have also stood stil 1. While the last statement at first appears contradictory, it does describe what has happened.

Proceedings Paper



Proposed AX.25 Level 2 Version 2.0 Changes
by Terry Fox, WB4JFI
Abstract: This paper is presented to document some of the major changes proposed over the last four vears of operation for the AX.25 Level 2 Version 2 Protocol. These changes have been collected by this author from various sources, and were recommended by a working group of the ARRL Digital Committee which met in Juiy of 1988.

Proceedings Paper



Transmission of IP Datagrams over NET/ROM Networks
by Daniel M. Frank, W9NK
Abstract: One of the main design goals of the Internet Protocol was that IP datagrams could be carried over existing local- and wide-area networks. This characteristic of IP makes it possible to build so called "internetworks" out of existing network facilities. We built support for an existing Amateur wide area network, NET/ROM, into the KA9Q TCP/IP package, allowing the use of NET/ROM to carry IP datagrams, and adding features which make the KA9Q software useful as a full duplex NET/ROM packet switch. We have also shown that NET/ROM may be used as a datagram network only, independent of its transport and application layer facilities.

Proceedings Paper



More and Faster Bits: A Look at Packet Radio's Future
by Bdale Garbee, N3EUA
Abstract: The biggest problem facing amateur packet radio today is the inability of the ham community to envision the breadth of possibilities that exist once higher speed modems become available. This paper attempts to survey some of the applications popular in other networking environments, and comments on their possible use in the amateur service. In addition, a preliminary report on work in progress to develop multi-megabit per second connections on the microwave bands is presented.

Proceedings Paper



Can We Continue to Ignore Level One?
by Eric S. Gustafson, N7CL
Abstract: For some reason which I cannot fathom, there has been a great reluctance to specify or even to provide guidelines for the various level 1 issues in the amateur packet radio system. This reluctance traces back all the uay to the very early days of packet radio development. I Sind this situation very strange indeed since if level 1 isn't uorking. all the other levels of the protocol uhich everyone eeems eager to specify doun to the last bit position are all irrelevant.

In this paper I will choose one of the most coneistently botched and yet most easily corrected level 1 parameters, the modem's data carrier detector. I will show how the performance of our present packet systems can be improved by careful consideration of even just this simple level 1 issue.

Proceedings Paper

Finger - A User Information Lookup Service
by Michael T. Horne, KA7AX
Abstract: With the recent explosion in amateur TCP/IP activity, primarily made possible by the KA9Q Internet Package, the need has arisen for a user information lookup service. Users on the amateur network can now retrieve important information about other amateurs through the use of a new application called fnger. This paper describes finger and its potential as an important source for information retrieval in the amateur networking world.

Proceedings Paper



Big Sky Telegraph and Other Tales
by Dave Hughes WNKV696
Abstract: Discussion on implementing packet radio to provide telecommunication services to schools.

Proceedings Paper



International Routing Designators
by Lew Jenkins, N6VV, David B. Toth, MD, VE3GYQ and H.N. Hank Oredson, W0RLI
Abstract: It has become obvious by now that the work-horse of our so-called packet network is the venerable BBS program. In fact, some will argue that it has been too successful. Every time that a band-aid is needed to "fix" the network, it is applied through the various BBS programs. It is probably fair to say that the maintenance of the forwarding tables is a drudgery that most sysops could do without. This point also under-scores a serious problem faced by all networks: ROUTING.

With the introduction of WORLI V7.00 and support for Hierarchical routing designators, we have an opportunity to improve traffic routing particularly for international traffic. Since N6VV is at the present time responsible for traffic to Asia and the Pacific, and occasionally Europe and Africa, he has implemented some Hierarchical routing designators which will assist him in international routing.

Proceedings Paper



AX.25 Packet Radio Communications Using Meteor Scatter Propagation
by Thomas Johansson, SM5IXE
Abstract: Meteor scatter propagation is commonly used in modern commercial and military digital communications. This traffic preferably takes place in the frequency range 30 to 50 MHz, where the reflectivity and duration of the meteor trails are the best. Meteor scatter links exhibit very reliable communication, even during periods of low meteor trail occurrence [2]. Among radio amateurs digital meteor burst communication has been discussed for many years. Despite this, no experiments on amateur basis have (to the knowledge of the author) been performed in Sweden or elsewhere in the world. During the past two years several amateurs have reported the random appearance of AX.25 packets from very distant stations. The propagation of these packets can only be explained by meteor scatter reflections. This supports the idea to exploit these reflections for packet radio links. The following paper reports on the realization and results of an initial experiment with packet radio communication using meteor scatter propagation in the 144 MHz amateur radio band. The tests were carried out during the meteor shower Geminides in the midst of December 1987.

Proceedings Paper



The AMSAT/TAPR DSP 1 Project: Hardware Design
by Lyle V. Johnson, WA7GXD
Abstract: This paper is intended to provide a design overview of the DSP 1 hardware configuration, sponsored by TAPR/AMSAT joint development project.

Proceedings Paper



MICROSAT Project - Flight CPU Hardware
by Lyle V. Johnson, WA7GXD and Charles L. Green, N0ADI
Abstract: This paper focuses on the design of the flight computer hardware and outlines some of its capabilities.

Proceedings Paper



RADIX 95: Binary to Text Data Conversion for Packet Radio
by James G. Jones, WD5IVD and Gerald A. Knezek, KB5EWV
Abstract: Binary files can prove to be difficult to transfer over the current amateur packet radio network. Radix 95 provides a way to convert data such as compiled programs or graphic images to printable ASCII characters and allow their transfer in Converse Mode. Radix 95 (base 95) iS a simple variable length encoding scheme which offers greater efficiency than is available with conventional fixed-length encoding procedures.

Proceedings Paper



Amateur TCP/IP: An Update
by Phil R. Karn, KA9Q
Abstract: Amateur radio use of the DARPA Inter-net protocols ("TCP/IP") has grown from a paper proposal during the "protocol wars" of several years ago to a well-established reality today. Because the TCP/IP software is free and available to radio amateurs and all other noncommercial users, it is hard to say exactly how many are using it. One rough estimate is the number of Internet addresses that have been assigned from the "network 44" block for amateur packet radio: about 1,000 amateurs in several dozen countries. The package has also gained considerable popularity outside of amateur radio, especially in universities.

With the popularity of TCP/IP on amateur radio has come another most welcome development: the appearance of others making substantial contributions to the software effort by creating new features and enhancing existing ones. Several of these contributors have documented their work in other papers in these proceedings, and any other potential contributors are also encouraged to do so. In this paper I will review the TCP/IP developments and experiments of the past year. Although I will mention several contributors by name, the project has grown much too large for this to be an exhaustive list; I hope no one will feel slighted if they are accidentally omitted.

In this paper I will also comment on some of the lessons learned so far, and then discuss possible directions for the future. As expected, much has been learned about the operational aspects of true computer networking on amateur packet radio. We've also learned quite a bit about coordinating the development of a com- plex software package when volunteers all over the world are involved.

Proceedings Paper



Cellular Area Coverage Transport Networks
by Donald V. Lemke, WB9MJN
Abstract: With the advent of level 3 software becoming widely available to Ham Packet Radio, a complete rethink of transport radio systems can lead to greater thruput improvements. This paper details a cellular area coverage transport system. Designed to be collision-free, and not significantly effected by modem lock-up times, this radio system would have thruput equivalent to modem data rate.

Proceedings Paper



9600 Baud Packet Radio Modem Design
by James Miller, BSc, G3RUH
Abstract: The theoretical minimum audio bandwidth required to send 9600 baud binary data is 4800 Hz. Since a typical NBFM radio has an unfiltered response from zero some 8 kHz, transmission of 9600 baud binary data is perfectly possible though it. This paper describes a successful implementation.

Proceedings Paper



ARES/Data: A Packet-Radio Database for Emergency Communications
by W.E. Moerner, WN6I and David Palmer, N6KL
Abstract: ARES/Data is a multiple connect specialized bulletin board system tailored to store and retrieve basic information about people, places or things during an emergency. The program is a generalized form of the FINDER program (Family Information Database for Emergency Responders) written by David Palmer, N6KL and W. E. Moerner, WN6I. Although ARES/Data allows access to the database via packet radio, the program can also operate stand-alone without the need for packet radio hardware. The actual operating mode is chosen by the system operator when the ARES/Data program is started.

ARES/Data is a system which allows collection and organization of information during a widespread emergency that overloads normal communications channels. The program is designed to be flexible, so that it can be used without change for both small and large disasters to organize information about victims, evacuees, locations, or even ham radio operators.

With alternate power sources and their own frequencies, Amateur Radio Emergency Service (ARES) operators can provide the ARES/Data service without tying up critical communications channels or relying on commercial power.

Proceedings Paper



PACSAT Software
by Harold Price, NK6K and Robert McGwier, N4HY
Abstract: The evolving structure of the Microsat system software is discussed. With a launch services agreement in hand, several "Pacsats" should be in orbit in 1989; they will have more memory and a more complex suite of system and application programs than any amateur spacecraft launched to date.

Proceedings Paper



Overview of ARRL Digital Committee Proposals for Enhancing the AX.25 Protocols into Revision 2.1
by Eric L. Scace, K3NA
Abstract: A working group within the ARRL Digital Committee has been evaluating enhancements and other proposals for improving AX.25. This paper summarizes the most significant items which are being proposed. You are invited to comment on these proposals. Comments are desired so that any final recommendations by the Committee will benefit from the broadest possible input.

Proceedings Paper



Introducing System Description Language for AX.25 and Related Protocols
by Eric L. Scace, K3NA
Abstract: This paper is part of a series of papers which provide extended finite state machine representations for AX.25 and related protocols. The state machines are depicted using state description language (SDL) graphic conventions from the Z.100 series of Recommendations developed by the International Telegraph and Telephone Consultative Committee (CCITT) of the Intemational Telecommunications Union (ITU). An extended finite state machine representation of a communications protocol such as AX.25 avoids the ambiguities associated with prose descriptions. These descriptions also compel the protocol designer to confront many of the error scenarios which arise on a communications path, and simplify the implementor's task of producing correct solutions which will interwork with solutions created by others.

This particular paper introduces the SDL symbols and explains other general aspects of SDL diagrams. It also lays out an organization of extended finite state machines which, together, perform the AX.25 link layer protocol, handle multiple simultaneous links, interact with the radio transmitter and receiver, and accomodate large data units sent by the application.

Proceedings Paper



AX.25 Data Link State Machine
by Eric L. Scace, K3NA
Abstract: This paper is part of a series of papers which provide extended finite state machine representations for AX.25 and related protocols. The state machines are depicted using state description language (SDL) graphic conventions from the Z.100 series of Recommendations developed by the International Telegraph and Telephone Consultative Committee (CCITT) of the Intemational Telecommunications Union (ITU). An extended finite state machine representation of a communications protocol such as AX.25 avoids the ambiguities associated with prose descriptions. These descriptions also compel the protocol designer to confront many of the error scenarios which arise on a communications path, and simplify the implementor's task of producing conect solutions which will interwork with solutions created by others.

This particular paper describes an extended finite state machine which executes the data link procedures between two stations.

Proceedings Paper



AX.25 Link Multiplexor State Machine
by Eric L. Scace, K3NA
Abstract: This paper is part of a series of papers which provide extended finite state machine representations for AX.25 and related protocols. The state machines are depicted using state description language (SDL) graphic conventions from the Z.100 series of Recommendations developed by the International Telegraph and Telephone Consultative Committee (CCITT) of the International Tdecommunications Union ~TU). An extended fnite state machine representation of a communications protocol such as AX.25 avoids the unbiguities associated with prose descriptions. These descriptions also compell the protocol designer to confront many of the error scenarios which uise on a communications path, und simplify the implementor's task of producing conect solutions which wiU interwork with solutions created by others.

This particular paper describes an extended finite state machine which supports multiple simultaneous AX.25 links. "Link" here embraces both AX.25 connections (established between two stations with the SABM command) and connectionless operation between two stations (using UI frumes exclusively). The main responsibilities of the link multiplexor SDL machine are to insure that each link has a fair and equal opportunity to access the radio channel, und to handle incoming frames which require digipeating.

Proceedings Paper



Simplex Physical Layer State Machine by
Eric L. Scace, K3NA
Abstract: This paper is part of a series of papers which provide extended finite state machine representations for AX.25 and related protocols. The state machines are depicted using state description language (SDL) graphic conventions from the Z.100 series of Recommendations developed by the International Telegraph and Telephone Consultative Committee (CCITT) of the International Tdecommunications Union ~TU). An extended fnite state machine representation of a communications protocol such as AX.25 avoids the unbiguities associated with prose descriptions. These descriptions also compell the protocol designer to confront many of the error scenarios which uise on a communications path, und simplify the implementor's task of producing conect solutions which wiU interwork with solutions created by others.

This particular paper describes an extended finite state machine suitanle for use on shared simplex radio channels; such channles represent the vast majority of environments where AX.25 is employed today. A sister paper describes a similar machine suitable for use on full-duplex channels.

Proceedings Paper



A Brief Note Proposing Non-Aloha Access Techniques for PACSATs
by Jeff W. Ward, G0/K8KA
Abstract: Carrier-sense multiple-access (CSMA), as used in most terrestrial packet radio networks, is not efficient for low-Earth orbiting store-and-forward packet satellites (PACSATs). This note describes a simple time-division multiple-access protocol for PACSATs. A procedure is proposed for eariy experiments on the UoSAT-D Packet Communications Experiment (PCE) transponder, using AX.25 as the link protocol with satellite-controlled TDMA arbitration.

Proceedings Paper



The UoSat-D Packet Communications Experiment
by Jeff Ward, G0/K8KA
Abstract: This paper describes the Packet Communications Experiment (PCE), which will be the primary payload on the UoSAT-D satellite. UoSAT-D is to be launched in 1989, along with several other Amateur PACSATs. The PCE design will be based on results of the UoSAT-OSCAR-11 Digital Communications Experiment, using an 80C186, 512 kbytes program RAM and 4 Mbytes message-storage RAM. It will be an open-access Amateur Radio PACSAT messaging system.

Proceedings Paper



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