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- Hartford, CT
Read the conference story with audio and photos.
22nd ARRL and TAPR Digital Communications Conference
September 19-21, 2003
- Solving Noise Problems in Modern Radio Systems
by Bryan Ackerly, VK3YNG
In recent times there has been a substantial increase in the use of
technology in radio systems. This sort of technology has been slow to
on in amateur circles due partially to the fear and misunderstanding of
noise problems associated with mixing RF systems with digital
Many amateurs to date have avoided the mixture ofthese technologies. In
contrast survival in the commercial world requires it to battle with
issues on a regular basis.
This paper draws on knowledge gained on both commercial and amateur projects that successfully combine these technologies and indicates methods that can be used to produce working designs.
- PMap...New Windows Based APRS Client Software
by John Blowsky, KB2SCS
Why was PMmap created? The software was created to fill the perceived
need for APRS client software
that not only follows the APRS spec. to the letter but also does APRS
like APRSdos. The software was
developed on a 133 MHz PC with 64 meg ofRam. PMmap has run also run on a
120 MHz Laptop with
16 Meg ofRam. The running on lesser computers fills the need for "Come
as you are" emergency
communications. Yes the software runs slow on the Laptop but not so slow
as to be unacceptable.
- AMSAT Oscar-Echo, SDR-1000, and Higher Speed
by Frank Brickle, AB2KT and Bob McGwier, N4HY
If all goes well, in May 2004 AMSAT-NA will launch its newest satellite
on the Dnepr LV (a converted SS-18) from a Russian launch site. The
satellite has the ability to support several digital modes. They will
be difficult to support using offthe shelf conventional transceivers.
Recently, a realistic candidate has emerged in the form of an affordable
and easily usable software defined radio (SDR). In this paper we will
describe the digital capabilities of AMSAT-ECHO, the new satellite, and
the software defined radio can be the ideal terrestrial station for
exploiting those modes. We will discuss the changes and upgrades to the
to be provided by the manufacturer, that will be necessary for this
- Overview of Dynamic Forward Routing
by Edwin Brownrigg
Dynamic Forward Routing (DFR) is a software implementation of two
U.S. patents (USPTO 6,044,062, March 28,2000; 6,249.516, June 19,2001)
that express the invention of a software defined Mesh Protocol. DFR,
in combination with Internet Protocol (IP), enables a metropolitan area
network to configure itself dynamically. In a multi-radio wireless
there are no pre-determined fixed paths. All routes are indeterminate.
Worse, there can be many indeterminate paths, which if taken without
can congest the network to the point of guaranteed failure.
- Exploiting the Dynamic Flexibility of Software
Radio in FM Broadcast Receivers
by Declan Flood, Linda Doyle, Philip Mackenzie, Keith Nolan, and Donal O'Mahony
This paper demonstrates how the flexibility of software radio may be
to optimise radio communications systems. It describes our
implementation of a
software radio RDS (Radio Data System) receiver. Most FM stations
transmit a RDS
signal in addition to their audio output. RDS provides information about
current FM broadcast such as the program name etc. RDS is very similar
North American RBDS (Radio Broadcast Data System). Our implementation of
receiver uses high level RDS information to adapt itself. The objective
improve the receiver's functionality for the user and to reduce the
- TNC-X: An Expandable Microcontroller-Based Terminal
by John Hansen, W2FS
TNC-X is a new Terminal Node Controller design based on the
Chepponis/Karn KISS protocol.]
It is implemented using a Microchip PIC 16F628 microcontroller, a CML
MX614 Bell 202 modem
chip, an 8K Ramtron FRAM, a Maxim MAX232A level converter chip, and a
dual op-amp which
provides active audio filtering for the modem. From the beginning, this
TNC was designed
to be small, have low power consumption, and, most importantly, be
Expandability stems from two sources. First there is an on board socket
for a DLP-USB232M
USB module which provides the TNC with a USB port. Drivers that are
shipped with the module
make it appear to the host PC as a standard serial port. Thus PC
software that expects to
see a serial port on the computer will interpret the TNC-X as being
connected to such a
port, even when the PC has no serial ports, or they are all used by
In addition, when the USB option is used, the TNC can be powered from
the USB port of the
computer; no other power supply is needed.
- Real-Time Speech with AX.25 - An Evaluation of the
Possibilities and Restrictions
by Nicolai Heilemann, DL9TS
A study about the possibilities of real-time speech transmission using
amateur packet radio
is presented. In this study it is shown, that a common 9600
Bitjs-channel has the
theoretical possibility of transmitting speech data with only short
The restrictions of the AX.25 protocol for real-time transmission are
that an appropriate setting of the transmission parameters still allows
real-time transmission. A hybrid emulation system using traces from a
channel as well as coded speech gives an estimation of the expected
speech quality and
an implementation of a real-time transmission tool allows first
results of these experiments show the possibility to use AX.25 for
transmission even if the resulting speech quality is not yet satisfying.
tolerance of listeners towards distortions has been much higher than
expected and there
are possibilities to improve the system with respect to the user
perceived speech quality.
- GPS Solutions for Tracking Applications in Steel
by R.K. Jha, K.K. Mallik, S. Jha, S.M. Mohanty, M.S. Sharma, and T Ravindra
GPS (Global Positioning System) is a satellite based radio navigation
system. The unique
feature of this system is that it allows users to determine their three
position, velocity and time anywhere in the world: be it land, sea or
many other applications initially developed for military purpose, it is
increasingly used for civilian purposes. GPS based vehicle tracking
system can have
various interesting and extremely useful applications in steel industry
raw material handling, hot metal and steel ladle movement, dispatch of
- The DSPx: An Experimenter's Module for Digital
by Lyle Johnson, KK7P
There has been interest in applying digital signal processing (DSP)
Amateur radio for more than a decade.
In the early 90's, AMSAT and TAPR teamed to produce a standalone external unit, the DSP-93. This kit provided advanced filtering and modems. Its cost was high, and a later effort was made to incorporate the Motorola DSP56002 Evaluation Module (EVM) into a similar enclosure. This was lower in cost and fairly popular, but Motorola soon discontinued the EVM.
In 1999, Bob Larkin, W7PUA published his DSP-lO Software Defined Radio articles in QST. This was built around an Analog Devices development board, which sold for only $89. This same board was the basis for all of the DSP experiments in the latest ARRL publication, Experimental Methods in Radio Frequency Design. Alas! Analog Devices increased the price of the evaluation board from $89 to $245, and has all but discontinued it in favor of more current technology. During the late 90's, soundcards began to appear in personal computers. Today, it is difficult to find a PC without a soundcard. And modem PC processors include DSP instructions which execute at incredibly fast rates. This has resulted in an explosion of available software to use the soundcard in conjunction with a radio to perfonn DSP tasks. Witness the explosion in popularity of "soundcard modes" such as PSK31.
What's an experimenter to do?
- SDR and VLF Time Signals
by Poul-Henning Kamp
VLF signals have been used to transmit precise time and frequency
signals since roughly
the second world war and even in these GPS days, DCF77 and WWVB signals
still responsible for getting more people out of bed in time than any
other time and
frequency distribution method.
This paper outlines some experiments on receiving a decoding these signals using a software defined radio, and the results obtained. For illustrations and data please see the URL in the paper.
- ERMTP: An Eventually-Reliable Message Transmission
Protocol for a Low-Bandwith HF Environment
by Huilong Huang, KD7YCO and Stephen Pink, KF1Y
Why Low-Bandwidth Reliability?
PSK31 has developed into one of the most popular digital modes of the last few years with its relatively easy to use software combined with a very efficient use of amateur spectrum. Another reason for PSK31's popularity is that all an amateur needs to have is a general purpose computer running the PSK31 software; i.e., no special hardware is required. The limiting factor, however, in PSK31 communication is that this mode supports only unreliable communication, making keyboard-to-keyboard chat about the only feasible application. Other services besides chat such as file transfer, email, etc. need support from the underlying channel that corrects for all (or most) errors in the communication. It seems impossible to support reliable communication with the kind of coded, lowbandwidth, simplex channel provided in PSK31. For such reliable communication support, one has had to resort to modes such as Pactor II, which uses many times more bandwidth and needs specialized hardware to provide a reliable and reasonably efficient channel of communication.
The purpose of this paper is to present a new protocol, the Eventually-Reliable Message Transport Protocol (ERMTP), that can provide reliable communications over low-bandwidth noisy radio channels such as HF. We envision this protocol to support such applications as email and file transfer and their variations such as world wide web communication. ERMTP uses a half-duplex channel that delivers packets or cells of data to the application that has been checked for accuracy by the sender and receiver. Our current implementation of ERMTP is based on PSKCore and, with some modification, can be used with current PSK31 user applications. Our intention is to create a reliable message service for the support of traditional data applications, yet retain the low-bandwidth quality of PSK31 as well as the reliance on PC sound-card-only hardware technology.
- Off the Shelf Digital Radio
by Victor Kean, K1LT
Need for Complex Antennas
I have been an avid 160-meter contester for a number of years. The 160-meter band interests me because the long wavelength makes antenna design a challenge not easily solved by the mere application of money. Furthermore, receiving antenna design becomes the focal point of station performance because of the nature of 160-meter propagation.
The standard approach to 160-meter receive antenna systems uses the Beverage Wave antenna. One strings a long wire, low to the ground (about 10 feet) for several hundred feet in the direction of the desired signal. A contest station typically uses 8 of these antennas to cover 8 compass points. The clever use of transformers allows one to use a parallel pair of wires to cover two opposite directions. A high performance-receiving array consists of 4 pairs of wires, about 800 feet long each laid out like a + and an X superimposed. Thus, the high-end station requires about 15 acres of land.
An array of verticals requires considerably less real estate for comparable directivity.
- The Future of ARQ in Congested HF Bands
by Peter Martinez, G3PLX
It is almost exactly 25 years to the day since the writer conducted the
in the use of Automatic Request (ARQ) techniques, introducing for the
first time the
concept of error-free delivery of messages over the error-prone HF
following this with the first experiments with automated
using ARQ links. This paper looks at the way in which ARQ techniques
have been used within
amateur radio since that time and attempts to extrapolate into the
future. The conclusions
reached are that current ARQ techniques have major flaws within the
context of today's
amateur radio community, and will have to undergo changes if the demand
message-handling is to continue as part of amateur radio into the next
- Telpac and Paclink - Streamlined AX.25 Packet
Server and Client for a Full Service Ham Radio Messaging Network
by Rick Muethng, KN6KB and Vic Poor, W5SMM
Ham radio's love affair with surplus hardware, budget software and a
volunteer spirit has served us well by keeping our hobby affordable
fostering many significant innovations. But the reality of high quality
is that it takes real programming skills and significant development
time to build
a worthwhile and reliable program. On-going enhancements and support
also pose tough
challenges when hams have come to expect free cradle-to-grave program
To manage development and maintenance efforts, a new approach had to be
writing next generation packet servers and clients. These programs must
be easy for
sysops and users to setup, provide intuitive familiar user interfaces
Netscape, Eudora) and reliably support both new and legacy BBS message
systems and TNCs.
This paper describes two examples of modem amateur packet programs
along with implementation approaches that minimized the development
provided solid foundations for future contributions and easy
- Direction Finding Abducted Children: Proposal for
a New Amateur Radio Emergency Service
by Brian Neill, VA3BPN
This paper is a proposal for a system that would enable amateur radio
pinpoint the location of an abducted child. Where possible the system
and protocol that is pervasive throughout the amateur radio community
such as 2-m
equipment, digital communications, direction finding equipment, APRS and
This system does require that the abducted child be carrying a special device. While this paper does not provide specifications for the actual device, a set of functional requirements are proposed in the hope that some qualified amateur will attempt to prototype and build a child location device (CLO).
Parent's and children's privacy are given due consideration throughout this paper. A number of security controls and mechanisms are included to ensure that police are the only party that is able to activate a child's device; and they must obtain key information from the parent before they are able to activate. The security oontrols aim to reduce the possibility of abuse, protecting the system and ultimately the child carrying a device (CLO).
Finally, the appendix suggests an operations framework to be used in a DF enabled search for an abducted child. This framework example is provided, as a means to describe how the ham community can respond to this class of emergency, should police ask their local amateur radio club for assistance.
- WAPaprs: APRS on a Cell Phone
by Richard Parry, W9IF
WAPaprs is an application to display APRS information on a cell phone
supports the Wireless Application Protocol (WAP). It was written to
useful APRS data within the size, memory, color, and bandwidth
of a wireless handheld device. The paper includes a description ofall
options and example displays.
- DSP Programming Using DirectSound and MFC/VC++
by Frank Perkins, WB5IPM
This paper discusses DSP programming using Microsoft DirectSound
and MFCNC++. Topics covered include an overview of Microsoft Windows
programming, the MFCNC++ framework, DirectSound, AX.25 demodulation and
packet decoding, and simple TCP/IP Winsock communications. A packet
monitoring program is used as an example. The link to the VC++ folder
for this program can be found at www.tapr.org in the "Conferences"
- A Digital PSK31 Meter
by George Rothbart, KF6VSG
Building a digital field strength meter for your PSK31 station.
See more details at www.ssiserver.com/info/pskmeter
- HSMM - High Speed Multi-Media
by Neil Sablatzky, K8IT and Mark Williams, AB8LN
HSMM -High Speed Multi-Media is focused on using IEEE 802.11b Standard
and adapting it to Part 97 Operation on 2.4 GHz.
- Southern California Coastal Propagation
by Ed Sack, W3NRG
During the Summer of2001, W3NRG set up a PSK1 BEACONet station1 on
28.131 MHz at his QTH
in Coronado, California. Almost immediately, the station began to record
signals of KF6XA whose Maidenhead locator code placed that station in
What made this reception interesting was that the distance between the
63 miles, is not characteristic of 10 meter ground wave propagation and
there are at
least three "mountains" in the path that obscure the simple line of
The BEACONet PSK31 signal protocol includes a preamble of approximately 30 characters followed by a "payload" consisting of station call letters, number of times per hour the beacon is being transmitted, a station configuration code, the Maidenhead locator and a cyclical redundancy check signature (CRC.) Stations are or have been active in various parts of the United States and in Europe and Australia. The recommended transmission timing is between six and twelve times per hour. Software is available to record the reception of signals which pass the cyclical redundancy test and, in certain cases, even send reports over the internet automatically at menu selectable times.
Early on in the KF6XA to W3NRG data collection process we recognized a definite time dependency on the number of confirmed reports received by W3NRG. We published our early data in a QST article in June 2002 A profile of the terrain between the two stations is shown in that article. The reviewers of the article provided various explanations for the propagation that was being observed.
- Speech Synthesis Added to PSK31
by Ed Sack, W3NRG
Radio Amateurs are well known for their keen interest in combining
several technologies to provide new features for the hobby. One such
combination is the use of computer speech synthesis to monitor PSK31
Thanks to the availability of an inexpensive speech synthesis program
freeware written by amateur N7YG it is now possible to listen to the
of a PSK31 stream rather than watching the text develop on the computer
- Vocoder Redux: The AMBE-2020
by Dennis Silage, K3DS
A Digital Voice Systems AMBE-2020 voice coder (vocoder) has been
as a functional replacement for the obsolete AMBE-IOOO. The effort, in
was a capstone senior design project in Electrical and Computer
Temple University, which fosters advanced technical topics in
education using amateur radio. The implementation is open-source and
with the data communication protocol ofthe original G4GUO AMBE-IOOO
design. This AMBE-2020 vocoder is offered as a reasonable standard for
radio digital voice experimentation. Further documentation for the
vocoder is available at www.temple.edu/k3tu.
- Legal Rules and Regulations in the Amateur Radio
by Miroslav "Misko" Skoric, YT7MPB
This paper analyzes some elements in domestic and international
that govern the use of the amateur radio service, as an embryo of the
professional and scientific activities in the ICT areas. After the
global and local
situation being carefully analyzed, the paper suggests some rules and
improvements, according to the actual state of the modern wireless and
- APRS IP Moblie in a Non-Dynamic Wireless
Environment or 802.11 APRS
by Darryl Smith, VK2TDS
The APRS Internet Service is a wonderful concept for a highly
distributed GIS system
for connecting hardwired users to the worldwide collection of APRS
the world is moving away from the idea of hardwired connections, and
the situation where users are wishing to access the data of the iGate
system whilst mobile.
While services such as FINDU.COM have the capability to send data to mobile devices such as laptops, PDA's and cell phones, this transmission of data is not necessarily bandwidth efficient -particularly when the maps are available already on the mobile device. Once colleague received a bill for about US$300 for his PDA for the month, with the majority from when he left FindU.COM running one night.
Whilst many of these devices allow a TCP/IP connection from the mobile device direct to the APRS Internet System (APRS-IS), the user is left with intermittent connections to the server -connections that are re-made when each new base station is encountered.
- Bazaar Ham Publicity: Applying the Bazaar Approach
to Ham Radio
by Darryl Smith, VK2TDS
Amateur Radio is not a hobby that has a single central controlling body,
Catholic Church. Yet many people think ofthe hobby as if it did have a
single body with the
will and resources to publicize the hobby. This paper describes some new
ways to think
of the hobby, and presents some ideas to publicize it.
This is NOT a technical paper. It is intended to provide ideas on how other technical concepts can be marketed to the world.
- SDR Update
by Gerald Youngblood, AD5OG
SDR-1000 Overview on the PC Based, Software Defined Radio
with Open Software - GNU Public License, including the full