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Sorry, ARRL 14th Digital Communications Conference 1995 is no longer available
This proceeding is available on CD-ROM
- Arlington, Texas
- Greg Jones, WD5IVD
- Dave Wolf, WO5H
- Dave Wolf, WO5H
- Hosted by:
- Tucson Amateur Packet Radio
- Texas Packet Radio Society
- Texas Packet Radio Society
14th Digital Communications Conference
September 9th, 1995
- Availability of Seventy 9600 baud Packet Channels on Two Meters
by Bob Bruninga, WB4APR
Unbelievable? Not Really! With the advent of the latest 9600 baud packet radio modems, there is an unexploited mechanism for opening up dozens of half duplex data channels without ANY impact on existing voice and data band plans. Read this proposal thoroughly before jumping to any conclusions.
- The WA4DSP 56 KILOBAUD RF Modem: A Major Redesign
by Dale Heatherington, WA4DSY
In 1987 I designed a 56 kilobaud RF modem which was sold in kit form by GRAPES, the Georgia Radio Amateur Packet Enthusiast Society. This paper describes how the WA4DSY 56 kilobaud RF modem was radically redesigned to lower cost, reduce size, and improved reliability, manufacturability and usability. The reader is referred to the ARRL publication Proceedings of the 6th Computer Network Conference, page 68 for details on the original design.
- Extended Sequence Number (modulo-128) option for AX.25
by Rob Janssen, PE1CHL
An extension to the AX.25 protocol is proposed, to enhance the efficiency of transmissions of large numbers of small packets on half-duplex interlinks. The sequence number space is increased from 8 to 128 to accommodate larger values of MAXFRAME, and procedures are described to enable monitoring of extended sequence number frames, and resequencing in case of frame loss.
- DSP-93 Update: The TAPR/AMSAT Joint DSP Project
by Greg Jones, WD5IVD, Bob Stricklin, N5BRG, Robert Diersing, N5AHD
This paper discusses the geniuses of the TAPR/AMSAT Joint DSP project. The end result was the TAPR/AMSAT DSP-93. As of July 1995, 300 units have been made available to amateurs for construction. Items to be covered include: a history of the project, history of the DSP-93, DSP-93 design, current software suite, code development, and comments on the successful use of Internet for project support.
- Introduction to Programming the TAPR/AMSAT DSP-93
by Ron Parsons, W5RKN, Don Haselwood, K4JPJ, Bob Stricklin, N5BRG
The purpose of this paper is to give a brief overview to assist potential programmers, new to the TAPR/AMSAT DSP-93 environment, insight into the tools and techniques available when developing for the DSP-93. The full developers/programming guide is available from TAPR.
- An Introduction to FlexNet
by Gunther Jost, DK7WJ, Donald Rotolo, N2IRZ
Features and operation of FlexNet packet networking software are discussed. Details of the software architecture, RMNC and MS-DOS hardware platforms, applications, user interface, adaptive parameters, and routing techniques are presented.
- Convolutional Decoders for Amateur Packet Radio
by Phil Karn, KA9Q
This paper describers two freely available convolutional decoders written in the C language. One implements the Fano algorithm for sequentially decoding three rate 1/2 K=32 codes while the other implements the Viterbi algorithm for maximum likelihood decoding of the rate 1/2 K-7 NASA standard code. Both support 8-bit soft-decision decoding with arbitrary metric tables and perform according to theory. Using GCC 2.6.3 under BSDI/OS 2.0 on an AMD 486DX4-100 CPU, the Fano decoder runs up to 375 kb/s while the Viterbi decoder runs at a constant speed of 75.1 kb/s. On a 90 MHz Intel Pentium, the speeds are 594kb/s (Fano) and 118 kb/s (Viterbi). This is fast enough to be useful in many amateur packet radio applications. The code is available over the Internet.
- Data Radio Standard Test Methods
by Burton Lang, VE2BMQ, Donald Rotolo, N2IRZ
The Data Radio Standard Test Methods document is introduced and explained. The document consists of a number of standardized test methods, written in a clear, step-by-step format. Each test method is designed to be easy to perform, including the proposed DRSTM database of measurement data.
- Modeling some Data Communications Functions using Microsoft Excel 5.0
by Thomas C. McDermott, N5EG
Recent enhancements to the Microsoft Excel spreadsheet program, version 5.0, provide some interesting features that may be of interest to those designing or analyzing data modems. This paper looks at the following examples: 1) bit error rate of a modem vs Eb/No in additive white gaussian noise (AWGN), 2) phase-locked loop response vs. loop filter parameters, and 3) modem eye patterns vs. channel response, and shows how each can be modeled with Excel 5.0.
- Building a Packet Network
by Karl Medcalf, WK5M
Since the beginning of amateur packet radio, users have tried to push the limits. This has taken many forms: how far can I get, how much data can I pass, how fast can I go. In 1987, Software 2000, Inc. developed the NET/ROM code, which replaced the EPROM in TAPR clone TNCs, in an attempt to improve the packet situation. This code provided the first attempt to build a network using amateur packet radio. Much of the current network software throughout the world is based on this code, and new implementations continue to arrive on the scene. This paper will present various viewpoints on network construction, and does not intend to imply that any one concept is superior to any other. It is intended to provide node operators (current and future) with ideas for consideration to help improve the existing system.
- DAMA - Another Network Solution
by Karl Medcalf, WK5M
This paper will discuss some of the drawbacks to the most widely used networking system (NET/ROM and its derivatives), and one idea to help alleviate some of the problems. It will explain, in some detail, the DAMA (Demand Assigned Multiple Access) protocol as proposed and implemented in some areas of the world.
- The Tulsa National Weather Service TexNet Interface Project
by Bob Morgan, WB5AOH, Greg Jones, WD5IVD
This paper details information concerning the interface to the NWS system in Tulsa by the TexNet network and how it can be replicated by other networking systems at other NWS sites. Several functions are provided from the TULSWX node including: automated severe weather alert broadcasts, emergency service broadcasts, color weather radar images using the NexRad Doppler (the WSR-88D), and the dissemination of messages directly to various EOCs and spotting groups.
- An Update on TexNet and the Texas Packet Radio Society
by Bob Morgan, WB5AOH, Greg Jones, WD5IVD
This article shows the current status and updates the progress and accomplishments, since the last published article in 1990, of the Texas Packet Radio Society, TexNet network, and other projects. The topics for this update codes the growth of the organization, the expansion of the network, the reliability aspects of the network, the latest firmware, and continuing projects.
- DSP-93 Programming Hints
by Frank H. Perkins, Jr., WB5IPM
TAPR/AMSAT DSP-93 is surprising user-friendly to program, considering it has a 40 MHz Harvard-architecture DSP processor under the hood. Applications can be successfully developed with only a PC and an oscilloscope. So far, more than a half dozen radio amateurs have developed and published applications for the DSP-93, including N5EG's windows-based oscilloscope and spectrum analyzer for the DSP-93, W3HCF's super-hot HF modem, a collection of satellite and terrestrial modems by this author, plus Mac versions of the spectrum analyzer and oscilloscope displays by W5RKN. In this paper, I offer you several hints on programming the DSP-93 that will hopefully get you around a couple of rough spots I have encountered. These hints are intended for someone with a working knowledge of assembly language programming, the 320C25 instruction set and the Programming Guide for the DSP-93.
- NETMGR: A Graphical Configuration for ROSE X.25 Packet Switch Networks
by William Slack, NX2P, Donald Rotolo, N2IRZ
NETMGR is a windows-based graphical configuration utility for ROSE X.25 Packet Switch networks. This paper describes the features and usage of the software in detail.
- Graphical Information Systems and Ham Radio (The future of APRS technologies)
by Keith Sproul, WU2Z
GIS is a major buzz-word in the scientific and computer graphics communities. GIS, or Graphical Information Systems (also sometimes called Geographical Information Systems) is the display of significant amounts of data on a graphical system, usually a map of some kind. This paper discusses various amateur GIS and the future of amateur GIS.
- AX.25 Transport Layer Drivers for TCP/IP
by Mark Sproul, KB2ICI, Tim Hayes, N2KBG
Current TCP/IP over packet radio is largely implemented with KA9Q's NOS and its many variations on PCs and NetMac on Macintoshes. NOS was written before good general purpose networking software was available and was written as an monolithic do-everything program. Today's multitasking operating systems have built-in networking support and there exists a large base of good server and client software for all platforms (Macs and Windows) that use this networking ability. Because of these things, a large, monolithic program is no longer needed and is actually a severe handicap. By implementing a transport layer AX.25 driver for use with system's native TCP/IP protocol stack, the existing programs that utilize TP/IP for Internet activities can be used for amateur packet radio activities. These include many excellent free and shareware programs for both Macs and Windows machines.
- The Puget Sound Amateur Radio TCP/IP Network
by Steve Stroh, N8GNJ
The Puget Sound Amateur Radio TCP/IP Network (also know as WETNET, the Washington Experimenter's Tcp/ip NETwork), centered in the Seattle, Washington metropolitan area, has built an extremely functional packet radio network based on TCP/IP networking and cellular RF techniques. The network encompasses more than eighteen separate Local Area Networks, an estimated 200 users, four 9600 baud bit regenerative repeaters, and a full time Internet gateway. This paper is intended to provide an overview of an operational Amateur Radio TCP/IP network.
- 6PACK - a 'real time' PC to TNC protocol
by Matthias Welwarsky, DG2FEF, Tom Sailer, HB9JNX
During the development of the PC/FlexNet software package, there was a strong desire to use the existing hardware, especially the very widespread TNC2, which populates almost every packet radio station nowadays. Sysops of the TheNetNode digipeaters also showed much interest, since many TNN nodes use TNC2 devices connected using a KISS token ring. 6PACK provides: data transparency, predictable capacity requirements on the ring, data and realtime information is distinguished, fast response to changing channel usage is provided, automatic ring setup replaces a channel number, and data is protected by a checksum.
- Skimming the Layers
by Ken Wickwire, KB1JY
Many parents have recently announced the rebirth of HF radio through the midwifery of digital signal processing. Newer and older hams have discovered or rediscovered the ionosphere as the place where PacTOR, GTOR, CLOVER and APRS hang out. Other amateurs connected with commercial or government HF
are excited about the increasing use of automatic link establishment (ALE), and of data modems with serial- and multi-tone waveforms, forward and reverse (ARQ) error correction, and equalizers. Government HF standards committees are well into the development of sophisticated software for adaptive communications at the Data Link and Network layers of HF data-transmission systems.
The purpose of this paper is to describe what it means to "measure HF digital performance" on the air, and to give an overview of what's needed (and available) for making such measurements. It will turn out that in most cases the hardware needed to assess over-the-air performance comes with the system to be assessed: if you have the system (usually a computer, a radio modem and an HF transceiver with an antenna), you have all the hardware you need. A surprising amount of freeware or shareware is also available. This paper surveys of some of that software.
- Recommendation for Hierarchical Address Protocol
by Dave Wolf, WO5H, Roy Engehausen, AA4RE, Hank Oredson, WORIL, Greg Jones, WD5IVD
The TAPR BBS Special Interest Group recommends the adoption of the x.3.4 hierarchical address protocol. This paper outlines that recommendation. The full proposal is available via Internet.