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DSP-93 The TAPR/AMSAT Joint DSP Program
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Introduction
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In July 1988, TAPR and AMSAT entered into the Joint DSP Program, in order to
fund the development of an eventual DSP unit for amateur usage. During the
summer of 1993, the direction of development was focused on a modular,
standalone DSP system proposed by Bob Stricklin, N5BRG, in Dallas, Texas.
The Stricklin DSP-93 design offered many of the things that the initial
design goals of the project had specified. TAPR and AMSAT are currently
taking orders on a periodic basis for units (see below). The DSP-93 is
supplied as a complete kit (including enclosure and power supply).
For those not wanting to build a kit, there are preassembled DSP units on
the market today. Ads for these units can be found in various publications.
It is our hope that the TAPR/AMSAT joint DSP-93 project will expand the use
of DSP in the amateur community and become a tool for education.
DSP-93 Design
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The DSP-93 is designed to provide radio amateurs the wonderful capabilities
of Digital Signal Processing in a stand-alone low-cost design. Not just
limited to one mode, the DSP-93 can support data, audio, and video modes
with the proper software.
DSP-93 has been designed in a modular fashion with two four-layer boards
utilizing an interconnecting bus structure. The basic system includes a DSP
engine board and a radio/computer interface board. The DSP Engine, bottom
board, contains the TMS320C25 DSP, 32K by 16 bits of program and data memory
- upgradable to 64K, the clock circuitry (40Mhz) and some programmable array
logic for system I/O. The Radio/Computer Interface Board, top board,
contains two eight pin female mini-DIN connectors for radio interfacing.
Incoming radio signals pass through a voltage divider to establish the
initial levels, then through an eight channel multiplex chip. The multiplex
chip then feeds the single A/D input with either of the radio inputs or one
of the six auxiliary inputs. The Texas Instruments TLC32044 Analog I/O chip
is used, which samples and updates at a rate of up to 45K operations per
second and includes aliasing filters. This board also communicates to your
computer at speeds up to 19.2K baud using a serial connection.
The modular design of the DSP-93 allows for either of these boards to be
replaced with future boards designed for any number of unique applications.
It's sort of like adding a new application card to a PC without redesigning
the complete PC. The block diagram shows how the DSP-93 is interfaced. (see
phamplet)
DSP-93 Software Suite
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As of November 15th, 1994, the following software has been made available
for the DSP-93:
1200 AFSK*, 300 AFSK*, 1200 PSK*, 9600 FSK terrestrial*, 9600 FSK
full-duplex for satellite operations, audio filters*, APT (Automatic Picture
Transmission modem), Digital Oscilloscope, HF modem* (RTTY, PCTOR, AMTOR),
test routines*, and user interfaces for MS Windows and Macintosh.
(* - indicates source is available for amateur non-commercial use.)
Software will be distributed on Internet, Amateur Satellites, and as part of
the TAPR software library. The idea of software for the DSP-93 is to make
it as easy as possible to get and upgrade software in the future. Since the
DSP-93 is an open architecture, it is hoped that as more amateurs get their
units, more software will be developed and distributed.
Code Development
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A low cost shareware assembler, TASM TMS320-25 Assembler, is available for
code development. To develop code for this board, you must have good
reference material. You can find numerous books on DSP algorithms and
developing DSP code. The manufacturer's data sheets and books for the
complex chips will also be good reference material. All the details needed
to write DSP code will be supplied with the kit.
To make this project a bigger success, more people are needed who want to
learn about developing DSP applications, networking, and converting from the
real linear world to the digital world. Ideally, everyone taking the
challenge will select a particular idea and become so focused in the
application that they become the expert. Some of the areas for development
might include: new modulation techniques, speech synthesis, filters,
spectrum analyzers, and many more applications you will think of. If you
choose to work on the hardware aspects of this project, the modular approach
should allow you to convert to other DSP chips or Analog I/O chips or to add
additional capability.
Ordering your Kit
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The DSP-93 sells for $430 as a complete kit, including enclosure and power
supply. For those not wanting to build a kit, there are several
preassembled DSP units on the market today. If you live in a country that
does not use 110v 60Hz AC, the price is $420, and the unit will ship without
the 9V AC wall transformer. (Please specify this in your order).
TAPR kits can be complex depending on the kitting experience of each
builder. We don't think you will have trouble with the DSP-93 kit, but it
does require some knowledge and experience to successfully go from a kit to
a finished, usable unit, depending on the mode of operations. For data
radio applications (i.e. 9600 baud FSK), special modifications must be made
to your radio for proper operation of the DSP-93. Unlike other TAPR kits in
the past, only the interface to the radio and the serial cable to the
computer (DB-9) will be the responsibility of the kit builder. All other
parts will be in the kit ready for complete assembly.
Due to the cost of each unit, TAPR and AMSAT are unable to fund the total
purchasing of inventory that may sit idle. Neither organization can sustain
such an investment. To avoid this possibility, TAPR and AMSAT are requiring
that kit purchasers provide VISA/MC information or checks/money orders with
their purchases.
Orders are being taken until December 31st, 1994 for March 1995 shipment.
Money for the kit purchase will be deposited on January 15th, 1995 to cover
kitting costs, with kits being shipped beginning March 15th. Orders will be
taken for 150 units. As of October 23rd, 50 orders have been placed.
In this way, the DSP-93 kit will be provided in the exact numbers required
for the demand. Many of the parts in the DSP-93 are between 10-15+ weeks.
DSP-93 kits will be provided in batches as the demand warrants doing kits.
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Orders can be mailed to the TAPR address: 8987-309 E. Tanque Verde Rd #337,
Tucson, Az, 85749-9399, call (817) 383-0000 (Office Hours: Tue-Fri,
9am-12noon, 3pm-5pm Central Time), or fax (817) 566-2544. If you have
questions concerning the unit, please write or call TAPR for an information
pamphlet. The pamphlet will also be made available via fax through the TAPR
voice system.
Note to TAPR members: Since this is a joint project, this kit will not have
a membership discount attached.
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References
Stricklin, Bob. (1994). TAPR/AMSAT Joint DSP Project: DSP-93.
Proceedings of the TAPR 1994 Annual Meeting. Tucson Amateur Packet Radio
Corp.
Stricklin, Bob and Greg Jones. (1993). TAPR/AMSAT DSP-93 Project.
Proceedings of the 1993 AMSAT-NA. AMSAT.
Stricklin, Bob. (1993). DSP-93: The Joint DSP Program (TAPR/AMSAT). Issue
#52, Fall 1993, Packet Status Register. pp. 4-5. Tucson Amateur Packet
Radio Corp.
