28th ARRL and TAPR Digital Communications Conference

October 25-27, 2009, Chicago, Illinois

A PS/2 Keyer: Using Keyer Paddles to Emulate a PS/2 Keyboard and Mouse
By David Bern, W2LNX, Montgomery College, Rockville, Maryland

Abstract: This paper describes my experience learning to program a Microchip PIC microcontroller in C. The program for this project emulates a PS/2 keyboard and a PS/2 mouse using CW keyer paddles for input.

Proceedings Paper

Universal Ham Radio Text Messaging – – A Programming Opportunity for TAPR
By Bob Bruninga, WB4APR

Abstract: Although most people think of Text Messaging as a recent phenomenon, they do not realize that amateur radio has had text messaging for over a century. This was recently well demonstrated on the Tonight Show with Jay Leno when two old hams using CW beat the socks off of two hip teenagers using text messaging on their cell phones. [0] Even though CW has yielded some turf to newer digital modes, amateur radio still relies heavily on an abundant tool box of instant text messaging capabilities. I recently counted over two dozen such systems currently active on amateur radio. The purpose of this article (a shortened version appeared in the September, 09 QST) is to not just review this broad capability, but in so doing, to inspire us to write interfaces and middleware to tie these systems together where possible to meet the following objective: Anytime, anywhere using any device, any ham can send a text message to any other ham by callsign alone using any digital device he may have in his immediate possession.

Proceedings Paper 

Matched Filter and Maximum a Posteriori Detector for Amateur Radio Digital Modes
By Rob Frohne, KL7NA and Mark Priddy, KE7UFF, Walla Walla University

Abstract: This paper describes a method of demodulating a digital signal that takes into account a priori probabilities of letters being sent to calculate posteriori probabilities of the letters given what was received. The letter with maximum probability can be chosen as the detected letter. The probabilities that the correct letter was chosen, given the signal received, can be useful for features like probability squelch and color coding letters with their probabilities so that better estimates of words received can be made by the human operator.

Proceedings Paper 

VSC-X: Using ZigBee to Implement a Virtual Serial Cable for Remote Programming of Mobile Radios
By John A. Hansen, Ph.D.,W2FS

Abstract: XBee-Pro is a relatively high power ZigBee-based module. This paper describes how to use these modules to create a virtual serial cable, allowing users to program their mobile radios remotely.

Proceedings Paper 

Serious RTTY contesting and the SO2R concept in 2007
By Kari Hirvonen, OH2BP

Abstract: In case you’re a good SO1R RTTY operator and look for a significant improvement, you should seriously consider to take a further step forward to SO2R in order to maximize your contest score. This report shows one example how to set up a serious Contesting Station using full size SO2R. This OH2BP is designed to serve mainly the RTTY mode, however all ideas and presented technology works fine for CW and SSB, too.

Proceedings Paper 

Planning a Digital-ATV Station for DVB-S
By Ken Konechy, W6HHC and Robbie Robinson, KB6CJZ, Orange County Amateur Radio Club (OCARC)

Abstract: Most ham radio Amateur Television (ATV) stations and repeaters in use today still utilize analog technology. The purpose of this paper is to explain Digital-ATV (DATV) to other hams, with the hope that it might make the transition from analog-ATV to Digital-ATV a little more straightforward. The paper begins with a review and comparison of various commercial DTV standards that are in use around the world. A top-down design methodology session is then conducted to sort through a number of design alternatives to plan a DATV station. The planning session chooses the DVB-S standard for DATV over the competing United States-based ATSC standard. The paper concludes by describing the Forward-Error-Correction factors and Symbol-Rate factors that determine the RF bandwidth for a DVB-S DATV station.

Proceedings Paper   –   Presentation Slides

Digital Television – the new Ham frontier
By Art Towslee, WA8RMC, Amateur Television of Central Ohio (ATCO)

Abstract: Digital television in the USA came into being commercially in the early 90s. Since then the official transition to all digital didn’t take place till June of 2009. Amateur television started somewhere around 2000 mainly in Europe with on the air signals not appearing until around 2002 when some digital board sets became available. Since then amateur repeaters in Europe have been increasing in popularity but sadly lacking in the USA. In January of 2004 the ATCO Group in Columbus, Ohio installed a DVB-S digital output to their repeater which has been in service 24-7 since then. As of July 2009, the ATCO Group is the only one in the USA with a repeater digital ATV output.

Proceedings Paper   –   Presentation Slides

How Does An SDR Transceiver Work?
By Patrick Lindecker, F6CTE

Abstract: This paper will describe an SdR transceiver, from an algebraic point of view (simple mathematics). Following are several principle electronic diagrams and two snapshots of the Multipsk SdR demodulator/modulator.

Proceedings Paper 

WRC-12 Agenda Item 1.19: Shaping the International Regulatory Framework for Software Defined and Cognitive Radio Systems
By Brennan T. Price, N4QX, ARRL, the national association for Amateur Radio

Abstract: World Radiocommunication Conferences, held roughly every four years, convene to consider amendments to international regulations and spectrum allocations necessary to accommodate new technologies and applications. The agenda for the next WRC, scheduled for January 23-February 17, 2012, in Geneva, invites delegates “to consider regulatory measures and their relevance, in order to enable the introduction of software-defined radio and cognitive radio systems, based on the results of ITU-R studies . . . .” Some of the issues being considered in these studies are discussed.

Proceedings Paper 

Experiments with Delay and Disruption Tolerant Networking in AX.25 and D-Star Networks
By John Ronan, EI7IG,  Kristian Walsh, Waterford Institute of Technology and Darren Long, G0HWW

Abstract: This paper examines the performance of DTN bundling layers against native protocols for radio data network with a view to possible deployment for emergency communications purposes. The authors conducted experiments with an existing DTN convergence layer in both AX.25 point-to-point and D-Star multi-hop communications links with hidden transmitters. The experimental results show that the DTN system exhibits marginally better performance than TCP/IP, appears to perform better where there are hidden transmitters, and has a more compact link utilisation pattern than TCP/IP. However, situations where obvious improvements can still be made were also identified.

Proceedings Paper 

Comparing 2-Meter Packet Radio Data Unicasts and Multicasts
By Paul D. Wiedemeier, Ph.D., KE5LKY, University of Louisiana at Monroe, Computer Science and Computer Information Systems Department

Abstract: Fairs, concerts, marathons, and festivals are public events where the local amateur radio club often assists the sponsoring organization(s) by providing communication services. These celebrations however, can be tarnished if a parent cannot find their child or a child cannot find their parent(s). During such situations, one site orally broadcasts the description of the child to all other sites participating a directed network. Unfortunately, oral descriptions can be ambiguous. A solution would be to transmit a digital image of the child along with the oral description. If all sites participating in a directed network have packet radio stations, then an optimal data transmission method would be for one site to transmit the digital image to all other sites simultaneously. This type of transmission is referred to as multicast and our data show that multicast file transfer tools should be used by the amateur radio community when transmitting digital data, imagery or otherwise.

Proceedings Paper