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Publications:

ARRL and TAPR 19th DCC Proceedings 2000

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Papers may be downloaded in PDF format by clicking on the link below each abstract. If you prefer, you may purchase a CD-ROM with the entire proceedings on it for this year and several others.

This proceeding is available on CD-ROM


Location:
Orlando, Florida

Coordinators:
Steve Stroh, N8GNJ, Conference Manager
Geoff Dick, WA4IKQ, Local Host Liaison

Hosted by:
Lake Monroe Amateur Radio Society (LMARS)
Orange County ARES/RACES
Seminole County ARES/RACES
Orlando Amateur Radio Club (OARC)


Read the conference story with audio and photos.


Abstracts:
19th ARRL and TAPR Digital Communications Conference
September 22-24, 2000

EasyTrak, A PIC /Based Rotor/Radio Controller Interface
by Steve Bible N7HPR
Abstract: EasyTrak is a rotor/radio controller interface based on the Microchip PIC16F87x series. PICmicro microcontroller. The goal was to design a rotor/radio interface that is compact, low-cost and easy to use. The PIC microcontroller contains many of the peripherals needed to design a rotor/radio controller interface: analog to digital converter (ADC), timers, serial interface (USART), and individually programmable I/O pins. In addition, the PIC contains FLASH ROM for easy programming and upgrades, RAM for system variables, and EEPROM for storage of non-volatile configuration information. With a small amount of interface circuitry around the PIC microcontroller, the goals of the compact and low-cost were obtained. Ease of use was obtained by designing EasyTrak to interface to the most popular azimuth/elevation rotors and a serial RS-232 interface to communicate with virtually any computer.

EasyTrak is designed to easily interface to the Yaesu series of azimuth/elevation rotors, model numbers G5400B, G5600, and the newest G5500. These rotors have a computer interface built in with an 8-pin DIN connector on the back of the rotor controller to control left, right, down, up and provide rotor position via a proportional 0-5 VDC analog signal for azimuth and elevation. EasyTrak can be interface to other rotors, for example rotating HF antennas, but will require user modification of the rotor controller. Optional relays can be installed on EasyTrak to provide normally-open (NO) or normally-closed (NC) contacts for azimuth, elevation, and brake.

The computer interface is via a serial RS-232 connection. The rotor controller protocol is based on Chris Jackson's, G7UPN, EasyComm protocol. EasyComm is a simple ASCII character based protocol for controlling rotors and radios. The benefit was that a new protocol did not have to be created, it is easy for programmers to write for and interface to, and several programs already have EasyComm programmed in: WiSP, Nova, MacDoppler, MacAPRS and WinAPRS. The Mac and WinAPRS programs have the unique feature of tracking high and low altitude balloons in azimuth and elevation as well as other objects. Mac and WinAPRS can also point HF beams using the DX Cluster feature or point to a moving object in azimuth only.

Proceedings Paper

APRS Tiny Web Pages
by Bob Bruninga WB4APR
Abstract: Although APRS has revolutionized packet radio, it is also one step ahead of the next great leap in wireless technology which is handheld wireless access to Web pages. Although cell phones and pagers are just beginning to capitalize on this next wave of technology, APRS already has it! Take a look at the screen of your Kenwood TH-D7 or TM-D700... What you see are hundreds of Tiny Web Pages of information!

Proceedings Paper

New Millenium Morse
by Roy Ekberg W0LIQ and Martin Schroedel K9LTL
Abstract: This covers aftereffects of 5 WPM Morse on Computer Assisted Communication (CAC) system proposed in the 17th ARRL and TAPR Proceedings. A prototype in ARRL's Library is indexed C-135-1. R & D on this began in 1989.

Proceedings Paper

Correlation for Direct Sequence Spread Spectrum
by Panagiotis Gavalas
Abstract: Spread Spectrum systems have become very 'trendy toys' in the areas of radio engineers and enthusiasts. Not only they provide privacy to the user, as an extend the ingenious channel encoding techniques involved make such systems very challenging for communications engineers and radio enthusiasts. Direct Sequence systems as the most preferred as they are the easiest to play with.  Sadly, among the articles and textbooks written on Spread Spectrum there are not many examples provided to the amateur radio enthusiasts. The concepts behind SS applications tend to be rather difficult to grasp and thus put the radio enthusiast in a very difficult position in terms of understanding and designing of such a system. As an extend, some already available examples demand the use of complicated circuitry and expensive ICs. Thus, amateur radio enthusiasts are put in the risk of loosing valuable time and money in case of failure or possible damage of expensive components due to the idiosyncrasies of such ICs. Thus an easy and cheap solution is necessary. This article is written in order to explain the concept of correlation in the simplest possible way to the amateur radio enthusiast and thus provide a simple solution concerning the heart of the system, i.e. the circuit that performs the de-spreading. It could be used as a reference or a manual and the circuit described has the potential to be adjusted to any Direct Sequence SS system used for digital data transmission.

Proceedings Paper

An MSK Mode for HF DX
by Murray Greenman, ZL1BPU and Nino Porcino, IZ8BLY
Abstract: Development of a very robust and sensitive modem for Amateur DX use. A description of the main problems involved in receiving digital modes on HF, and ways to counter them; a brief history of MFSK, and a description of MFSK technology. A description of the design process of a new MFSK mode for amateurs, its performance, and the software used to demonstrate it.

Proceedings Paper

A Zero-IF Digitized Despreading Scheme Without PN Code Synchronization Recovery
by a href="mailto:hguo@mcn.xidian.edu.cn">Hong Guo, Feng Guo and Tao Duan
Abstract: Zero-IF is a important method to digitize the despreading. In this paper, a fast zero-IF digital dispreading scheme with PN code synchronization recovery is given, which is based on performance analysis to chip rate sampling in AD converter.

Proceedings Paper

PIC-et Radio II: How to Receive AX.25 UI Frames Using Inexpensive PIC Microcontrollers
by John A. Hansen, W2FS
Abstract: This paper provides step by step documentation of how to decode AX.25 UI frames using inexpensive PIC microcontrollers. It is designed primarily for those who wish to receive packet radio UI beacons from point to multipoint communications. The article assumes some knowledge of programming concepts and PIC microcontrollers.

Proceedings Paper

Winlink 2000 ...A Global Ham Message Transfer and Deliver Network
by Hans Kessler, N8PGR, and Vic Poor W5SMM, Rick Muething KN6KZB, and Steve Waterman K4CJX
Abstract: Early digital modes broke from the traditional "live" interactive QSO and fathered the now familiar store and forward message systems we now take for granted in our BBSs and e-mail. The increased demand for mobility in Ham radio has evolved into the need for a reliable, rapid, global message transfer and delivery network that spans both the Ham radio and Internet domains. This paper describes the implementation of the next generation Ham message and information network that allows mobile users global connectivity to other amateurs, Internet mail users and WEB based information while remaining free of the constraints of the "home" BBS. Winlink 2000 is now a fully operational global network serving thousands of mobile ham users and providing reliable connectivity for both text, and binary data.

Proceedings Paper

Frequency Offset Acquisition and Tracking Algorithms, Part 1
by Mohamed K. Nezami
Abstract: Wireless receivers process signals that bear information as well as disturbances caused by the transmitter/receiver circuits and channel impairments such as fading, interference, and additive white gaussian noise (AWGN). Usually, the receiver knows only some statistical properties of the signal and disturbances. From these statistical properties and using a finite observation of the received signal, the receiver is able to estimate the transmitted data symbols.

Proceedings Paper

Frequency Offset Acquisition and Tracking Algorithms, Part 2
by Mohamed K. Nezami
Abstract: In part I, several algorithms were developed for carrier frequency offset acquisition. The algorithms estimate the offset frequency independent of the carrier phase errors or symbol timing. Phase errors are estimated and corrected, after frequency estimation and correction as shown in figure 1 of part 1. In part II, phase estimation algorithms using open loops and close loops techniques are presented, a particular application example will be the use of both techniques for acquiring and tracking short TDMA burst satellites. Finally, practical methods for implementing these algorithms using commercial DSP chips are introduced.

Proceedings Paper

QuakeAPRS
by Richard Parry, W9IF
Abstract: QuakeAPRS provides the APRS network with near real-time earthquake information. It is a perl script run as a cron job on a Linux machine. When the script is executed on the hour and half hour, it connects to the USGS to collect earthquake data. It then converts the information to the standard APRS packet format and sends it via the Internet to APRServe. This allows APRS clients to easily display and track earthquakes. QuakeAPRS has been running 24/7 for nearly a year. This paper describes QuakeAPRS, the earthquake object format, and lessons learned from the development of this applications.

Proceedings Paper

Soundmodem on Modern Operating Systems
by Thomas Sailer HB9JNX / AE4WA
Abstract: Five years ago I presented drivers for using standard PC's with soundcards as packet radio modems [13]. The mainstream CPUs of that era were not quite powerful enough for complex signal processing, so the design at that time had to trade robustness for computational simplicity. Furthermore, operating system preferences have changed since. It is therefore time to rethink the design. In this article, an up to date implementation of an amateur soundcard packet radio driver is presented that features a common source base supporting all major operating systems, and the most common modulation formats.

Proceedings Paper

External Common Gateway Interface (CGI) Access to FindU
by Thomas M. Schaefer, NY4I
Abstract: This paper provides programmer documentation on external access to the FindU database. The Common Gateway Interface (CGI) is used as an example of methods for a script or program written on a web server to access that database.

Proceedings Paper

Server Applications within APRS Internet Server Environment
by Thomas M. Schaefer, NY4I
Abstract: This paper discusses programmatic opportunities to access the Internet servers offering APRS data. Particular attention is made to the APRServe system in Miami. Using this system, it is possible for a programmer to create applications that utilize APRS data to create new dynamic and useful applications.

Proceedings Paper

Intelligent Filtering of the APRS Internet Gateway Data Streams
by Darryl Smith, VK2TDS
Abstract: APRS is a fast growing mode throughout the Amateur Radio world, thanks to its combination of computers, radio, packet and the Internet. Such popularity has increased the amount of data on the APRS network to a point where many users, especially those outside North America, are overwhelmed by the volume, or in an attempt to reduce the traffic volume do not enjoy the full benefits if Internet Connected APRS. This paper describes work by the Author into filtering the data stream intelligently to create manageable local networks.

Proceedings Paper

APRS and the TAPR EasyTrak Az/El Rotor Control System
by Keith Sproul, WU2Z
Abstract: APRS, Automatic Position Reporting System, has been used to track many things. It has been used with DX Cluster for showing where the DX stations are located. It has been used to track cars, boats, bicycles, motorcycles, weather balloons, and hot air balloons. It has even been flown on the Energizer Bunny Hot Air Balloon many times. When tracking balloons, especially the high-altitude weather balloons, normal antennas work fine for the Packet/APRS/GPS signals. But when you are trying to receive ATV (Amateur Television) signals from the balloon, you need much better antennas. Usually you need to have a high-gain antenna of some type pointed directly at the balloon. APRS already knows where you are, and it knows where the other stations are. From this information, it is easy to calculate the angle(s) needed to point a directional antenna at the other station, when needed.

Proceedings Paper

APRS and Kenwood TM-D700 Voice Messaging
by Keith Sproul, WU2Z and Mark Sproul, KB2ICI
Abstract: MacAPRS has had speech capabilities for messaging for many years. WinAPRS has the ability to use wave files for some functions. APRS Plus has wave file capabilities too. To put voice features on a normal computer is easy. Last year we wrote a paper about wanting a message 'speaking" device using some kind of text to speech system if we could find one. These do exist, but they are not cheap, and also are not very small. Last year, Kenwood introduced the TM-D700 which had the ability to do some of what we wanted, built right into the radio. This 'speech' feature has proved to be very useful. This paper is about the voice messaging feature of the Kenwood TM-D700.

Proceedings Paper

Internet Wide Callsign Database using LDAP
by Mark Sproul, KB2ICI
Abstract: LDAP, Lightweight Directory Access Protocol, is an internet protocol for storing directories. It has many uses but the most common use is for keeping track of large lists of personnel. Many attributes can be associated with each entry such as name, email address and callsign. LDAP is a standard and is easy to incorporate support for it in any application. There are libraries for use with C/C++ Java, PHP and many other languages as well as all platforms. LDAP is also supported already in many end-user applications such as Netscape.

Proceedings Paper

<APRSdec>--The G3NRW APRS Packet Decoder
by Ian Wade, G3NRW
Abstract: This paper describes the principal features of the <APRSdec> program. The program fully decodes raw APRS packets, producing reports in plain English. It has proved to be an extremely useful APRS diagnostic and learning tool. <APRSdec> is written in Perl, and runs under native DOS, Windows, Unix, and Linux. It is available from http://www.tapr.org/~g3nrw.

Proceedings Paper

Throughput and Probability of Correct Message Transfer of the Pactor-II System Measured on Near-Vertical-Incidence-Skywave (NVIS) Paths
by Ken Wickwire KB1JY, Mike Bernock KB1PZ, and Dave Willard W1EO
Abstract: This paper is another in our series treating on-air measurement of throughput in characters per second (cps) for various HF data-transmission protocols of interest to amateurs (see the references to our other reports at the end of the paper). Here we describe an extensive set of measurements of throughput for compressed and uncompressed text files sent over near-vertical incidence-skywave (NVIS) paths with the Pactor-II data transfer protocol. The implementation we used was the one in the Special Communications System (SCS) modem.

Proceedings Paper

Automatic Voice Relay System - (AVRS)
by Bob Bruninga, WB4APR
Abstract: AVRS is a "VOICE" addition to APRS. Just like APRS now provides mobile-to-mobile worldwide MESSAGE capability via the Internet APRServe system, there is no reason why we cannot add voice to this same type infrastructure for mobile-to-mobile voice. And AVRS is not limited to one channel It can be expanded to as many channels as the locals want (i.e., it can handle explosive growth)... Internet connection of local Repeaters is not new. Iphone links have been going on for several years, but with the lack of any common user commandable access-on-demand and the completion for on-air time with conventional use of the repeaters, it remains as just a novelty. But, by tying this capability into the command structure and worldwide text messaging capability of APRS the mobile user would then have total control and could "dial up" a link anywhere on the planet. Remember, he can already communicate by text message to confirm the other person is on the air. AVRS then lets him open a voice link to that same area.

Proceedings Paper

Intelligent Digipeating using DIGI_NED on Obsolete PCs
by Henk de Groot, PE1DNN
Abstract: In Europe the roll-out of APRS is well under way right now. However, we do not have a stable APRS infrastructure. This paper describes how we use old and obsolete PCs, together with packet hardware commonly used in western Europe, to augment the APRS infrastructure.

Proceedings Paper

Channel Capacity Simulation of Peer-to-Peer Spread Spectrum Satellite Transponders
by Matthew Ettus, N2MJI
Abstract: A spread spectrum transponder for the International Space Station has been proposed, the goal of which is to provide medium to high bit rate digital communications to radio amateurs. In order to help predict the capabilities of such a system, as well as aid in its design, a simulation of system bit error rates has been performed. The simulation is performed at the channel symbol ("chip") level, using a freely available communications system simulator package. The results of these simulations show that over a hundred users may participate in digital voice communications at any time using the transponder.

Proceedings Paper

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