Copies of the papers presented at, or published for DCC are available in various ways. A paper printed in the proceedings will be available for purchase in most cases in hard copy as the DCC proceedings. It will in most cases also be available as an individual paper in PDF format as a free download via a link below the abstract (where available) It may also be available on CD-ROM. A paper printed in the proceedings may not have been presented at the conference. Also a presentation at DCC may not be in the printed proceedings. In those cases it may be available on DVD, CD-ROM or as a MP3 download. Links to what is available will be on the page specific to the particular year's DCC.
- Des Moines, Iowa
- Local Sponsors:
- Central Iowa Technical Society (CITS)
- Amateur Radio and Computer Society (ARCS)
- Des Moines Radio Amateur Association (ARCS)
- Amateur Radio and Computer Society (ARCS)
Read the conference story with audio and photos.
23rd ARRL and TAPR Digital Communications Conference
September 10-12th, 2004
- DttSP: An SDR core in C
by Frank Brickle, AB2KT and Bob McGwier, N4HY
Last year at this conference we presented an overview (AMSAT OSCAR Echo,
SDR-1000, and HigherspeedFSK, by Frank Brickle, AB2KT and Bob McGwier,
N4HY) of the design for a suite of software to implement a Software
Defined Radio initially for the FlexRadio SDR-IOOO. We described the
functional breakdown of the software and the overriding design goals and
principles that were to guide the development.
The first iteration of that software is complete. It is currently embedded in the new SDR-IOOO console running under Windows. However, the DSP core is independent of the Windows version -indeed, it is basically independent of the SDR-IOOO hardware as well. We are currently completing the parallel Linux version of the console and are poised to start the inevitable rewrite of the core software. What we would like to describe here are the revised estimates of what the software is good for, and further, where it will be going over the next few months.
- Overview of Dynamic Forwarding Routing
by Edwin Brownrigg
Dynamic Forward Routing (DFR) is the expression of two US patents (USPTO
6,044,062, March 28, 2000; 6,249.516, June 19, 2001) for the invention
of a software defined Mesh protocol. DFR, used in combination with
Internet Protocol (IP), enables a metropolitan area network to configure
itself dynamically. In a multi-radio wireless network, there are no
predetermined fixed paths. All routes are indeterminate. Worse, there
can be many indeterminate paths, which if taken without intelligence can
congest the network to the point of guaranteed failure.
- KidCQ: A Prototype System for Direction Finding
by Caroline Guay, VA3WYZ, Mike Kennedy, VA3TEC and Brian Neill, VA3BPN
This paper was written to document the design and implementation of the
KidCQ prototype tracking system which could help in locating abducted
children. KidCQ places an emphasis on protecting the privacy of
children. Strong protective mechanisms have been incorporated to prevent
fraudulent use of this tracking system.
- The Micro908 Antenna Analyst
by George Heron, N2APB and Joe Everhart, N2CX
Here's a low cost and portable microcontroller-based instrument that
automatically determines SWR and reactance characteristics of an HF
antenna system. Advanced features of DDS frequency control, LCD tuning
display, PC data collection and plotting, numerous operating modes and
easy software upgradability make this design attractive for homebrewers
and antenna enthusiasts.
- A General Format for Data Compression
by Han Javan and Mike Fulton
Transmission of huge amount of data, either analog or digital requires
significant amount of bandwidth and processing time. Data companding can
reduce the required bandwidth and the transmission time to an acceptable
level. Analog companding have been fully developed and several
companding methods such as u-Law and A-Law compression methods are now
in commercial use. They are basically log amplifiers. But it was not
until 1970 with the event of personal computers that digital companding
received special attention. Although several software have been
developed but there seems to be no a general format for digital data
This article addresses a new general method for companding any digital data by introducing a new compression format. Specifically a method will be introduced to convert a 16 bits data to 12 bits then to an eight and finally to 6 bits, thus reducing the bandwidth and transmission time by a factor of 16/6. The recovered data, depending on resolution and dynamic range of the sampled signal may have some inevitable error, which is the fundamental drawback of every compression method. However, it will be shown mathematically that the suggested method forces this error to attain a minimum possible value not to exceed allowed resolution.
- A Systems Approach to Amateur Radio
by Peleg Lapid, 4XlGP
For more than 5O years, observing, from my corner of the world, being a
Ham and using my training and expertise as a systems engineer and
communications engineer I watch the development and deployment of radio
amateur step by step in parallel with and from time to time ahead of the
commercial and military communications. I recall the MCW and CW than AM,
SSB, the digital modes AMTOR (maritime TOR), AX25-Packet and so on.
During the last decade I have seen some new development within the
amateur community, namely: -the PSK31, Pactor and others.
Since we are not bound any longer by analog signal processing, and can use the power of digital processing this is the time to rethink what we wish our hobby to look in the coming years. Will it stay with CW, SSB, and the known digital modes? Or, to my point of view, can we have a "Master Plan" or a "Model" for the future to enable a new era of radio amateur communications based on the power of the digital processing.
- Digital Chat Modes
by Patrick Lindecker, F6CTE
The following paragraphs describe some Ham digital "chat" modes. High
rate digital modes for file transmission as CLOVER, PACTOR I and II or
HF Packet are not covered here.
- PSKFEC31 and PSK63F
by Patrick Lindecker, F6CTE
In this paper, I will describe two digital modes "keyboard to keyboard"
of PSK (Phase Shift Keying) type: the PSKFEC31 and the PSK63F, both
provided with a error correction capability, this with the goal to show
the type of problem that one can meet when creating a new digital mode.
These modes and many more are available in one of the software developed by the author, program which name is Multipsk, downloadable from the following WEB site: http://members.aol.com/f6cte/
- Anatomy of an APRS-IS Server
by Pete Loveall, AE5PL
(The Evolution of javAPRSSrvr and Its Adjuncts) In 2002, APRS-IS (APRS
on the Internet) was in disarray and bordering on collapse. There were
three core servers through which every packet in APRS-IS was supposed to
pass. first.aprs.net was running aprsd on Linux, second.aprs.net was
running APRServe on Mac as 9, and third.aprs.net was running aprsd on
FreeBSD Unix. There were over one hundred non-core servers, most running
various versions of aprsd and some running AHub. So, what were the
- Update on the TAPR VNA Project
by Tom McDermott, N5EG
The paper reports on the status of the TAPR Vector Network Analyzer
project, a 200 KHz to 100 MHz USB-based vector network analyzer. Changes
since the project was published in the July/August 2004 issue of QEX
magazine include a beta test, lessons learned during the beta test, and
suggestions for further improvements.
- SCAMP (Sound Card Amateur Message Protocol)
by Rick Muething, KN6KB
Digital modes enjoy increasing popularity and performance thanks to a
better understanding of Digital Signal Processing (DSP) and continual
improvement in the performance of modern computers, sound cards, and
operating systems. SCAMP is a new experimental "wide-band" (2 KHz)
digital sound card message protocol suitable for HF. SCAMP leverages
the work by Barry Sanderson, KB9VAK and employs an ARQ "wrapper" around
Barry's Redundant Digital File Transfer (RDFT) scheme to provide the
error-free automatic operation necessary for today's modern digital
message systems. This paper documents work in process developing and
testing a new sound card mode that promises Pactor-like performance for
HF channel transmission.
- Digital Messaging for AERS, A Progress Report
by Victor Poor, W5SMM
At the July 2003 meeting the ARRL Board resolved to establish an ad hoc
committee of members to develop a comprehensive program to enhance the
current ARES emergency communications capability to include rapid and
accurate handling of long range (inter-state, national, and
international) emergency communications. This led to the formation of
the ARESCOM committee in September 2003.
At the July 2004 ARRL Board meeting the chairman of the ARRL ARESCOM committee presented the committee's final recommendations to the ARRL Board where it received unanimous acceptance. This paper summarizes some of the committee's recommendations and the technical implications of implementing them.
- Design and Implementation of Receiver System for
Suppressing Radio Frequency Interference Using Adaptice Filters
by K. Jeeva Priya
Radio Frequency Interference (RFI) is increasingly affecting radio
astronomy observations. Recent interference mitigation techniques
developed for communication engineering have been applied in radio
astronomy. However, RFI rejection achieved till now is not sufficient
for radio astronomy. Research in developing new techniques is therefore
This paper describes an improvised technique of RFI suppression by adaptive filters by constraining the bandwidth of the reference signal and also to study the effects of quantisation of bits to suppress RFI.
- A Practical Evaluation and Comparison of Some
Modern Data Modes
by Steve Richards, G4HPE
This report aims to make recommendations for the use of modem data modes
when considered for the purpose of broadcasting textual information (few
transmitters to many receivers) over Amateur Radio HF paths.
It is suggested that modern data modes could find an application in amateur emergency HF communications. The possibility of 'broadcasting' messages and information is of interest here. For example, it may be possible to provide a UK-wide service from a single, or a few, well-appointed stations. Because ofthe comparative ease with which an HF data receive-only facility can be established at temporary locations, a national information system might be an achievable goal for radio amateurs. Such a facility might, for example, carry low-precedence traffic in order to free official channels for more important messages.
- Continuing the KF6XA/W3NRG Propnet Experiment Non
Reciprocal Beacon Capture
by Ed Sack, W3NRG
In June 2002, we reported an unusual propagation phenomenon observed in
the process of participation in the Beaconet/Propnet program on 10
meters. In an article published in QST, we documented fairly consistent
reception of KF6XA's beacon signals at W3NRG even though the distance
and the terrain between the two stations would not lead one to expect
regular communications on that frequency. KF6XA is located at Murrieta,
CA and W3NRG is located at Coronado, CA. The stations are on an almost
exact north-south line, 63 miles apart, with several high peaks along
In September 2003, we noted that a phenomenon similar to what we were witnessing had been reported in a WorldWarII study of propagation along a similar path. The authors of that study hypothesized that a sharp demarcation between cold and moist air at lower levels over San Diego and very dry warm air at higher levels was responsible for the unusual propagation conditions that were being observed.
- Spread Spectrum Power Control
by Darryl Smith, VK2TDS
The FCC when they were drafting the Part 97 rules for Spread Spectrum
felt that power control was something that should be included in
operations of higher power links. One presumes that they felt that at
lower powers the added complexity of power control was not needed given
the low probability of interference.
When they were writing these rules they could never have imagined the number of spread spectrum devices that would potentially be sharing the bandwidth just a few years later.
The purpose of this paper is to encourage the use of automatic power control in spread spectrum operations for all users, even those operating under Part 15.
- D-STAR: Digitally Modulated Voice and High Speed
by Matthew F Yellen, KB7TSE
An overview of D-Star and its potential uses.
- Software Defined Radios - The Future is Now
by Gerald Youngblood, AC5OG, Bob McGwier, N4HY and Eric Wachsmann
- Abstract: A Software Defined Radio (SDR) is a radio in which all modulation and demodulation functions are defined, and therefore configurable, through software. This creates tremendous flexibility to improve and adapt the capabilities of the radio over time without changing the hardware. The potential for amateur radio experimentation is virtually limitless in terms of performance improvement and the introduction of new operating modes. This paper takes a look at the FlexRadio Systems SDR-1000 architecture and capabilities.