TAPR Packet Status Register 051

14 Pages·1993·1 MB·English

by  TAPR

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n
ISITIAITIUISI
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Tucson Amateur Packet Radio Corporation
Summer 1993 President’s Report
Issue # 51 Although summer is ending, TAPR is getting geared up for the remaining half
of the year and starting to plan 1994. La me attempt to summarize what has been
happening since the annual meeting.
Published by:
The TAPR/AMSAT DSP project is moving forward. We should have a full
Tucson Amateur Packet Radio
article on the new design in die next PSR. No commitment on dates, but we have
PO Box 12925
Tucson. AZ 85732-2925 determined that we will be doing a limited first run for beta-test units before we do
Phone:[phone] the final kit production (see article inside).
FAX: [phone]
The TrakBox kits have finally been finished. Due to summer vacation schedules
Office Hours:
and getting in the last few hard-to-find parts, we were about a month off from our
Tuesday - Friday
10:00am -3:00pm M.S.T. initial guesstimate on kit sales.
17:00 - 22:00 UTC
Paul Newland, AD7I, has approached the board with a proposal for a new project
called PCON. PCON (A Simple Printer Controller for Parallel Printers and Serial
Editor: Mechanical Teleprinters) has been accepted by die board and Paul is continuing his
Bob Hansen, N2GDE
development PCON. in its most basic form, is a printer controller that serves to
POBox 1902
convert serial asynchronous ASCII data to a format suitable for driving a parallel
Elmira. NY 14902-1902
printer (or ASCH/BAUDOT serial asynchronous teleprinter). A typical use for
CompuServe: 71121,1007
PCON would be to interface a parallel printer to a packet radio TNC. Such a system
Internet: [email protected]
provides the functionality of a “rip-and-read” message printing system where the
person receiving the message doesn’t need to know anything about radio or
In This Issue... computers. Numerous emergency applications are possible. Paul will be providing
TAPR Project Proposal Format....2 a full write-up for the next PSR. If you have a project that you want TAPR to
Notes trom the TAPR Office...... 3 examine for possible release as a kit or for technical feedback, refer to the article on
DSP Project Update..............3 submitting projects.
The TrakBox Project............. 4
The TAPR e-mail server has been set up and is now operational. Lou Nigro,
TrakBox again available
KW7H, is administrating the system. Lou is also the TAPR software Librarian. The
from TAPR.................. 4
board has moved off CompuServe and now uses the mail server for all of its
An Automatic Doppler Correction
communicadons. There are a few more things to be waked out, but over-all the
Circuit tor FSK/FM Satellites...5
change has been a good one. We will be setting up a mail distribution system in the
RealTrak....... ............... 6
near future in order to disseminate information between PSR issues.
ITAMSAT Project Stake..........6
All G3RUH Modems Although sales from the office have been slow this summer, financially, TAPR
An Not toe Same— ......... 7 is still showing a net gain for the year. This is a direct result of everyone in the
1994 Annual TAPR Meeting.......7 organization paying special attention to expenses. We hope to continue this trend
1993ARRL Conference on and keep things in the black for the entire year. Don’t forget the office is open
Digital Communications....... 8 Tuesday through Friday from 10am till 3pm MST. Heather always likes to hear
Valley Forge from you, so give the office a call if you need anything. In Oder to help keep
HAMSHOWS1993 Convention. 8 membership dues up-to-date, TAPR will begin to mail out renewal letters from time
TNC-2andthe to time. We all understand it is sometimes hard to see that your membership has
TAPR 9600 bps Modem.......9 expired from receiving the PSR, since most folks don ’ t prioritize reading the mailing
Forward Enor Correction........ 10 label (grin). This mailing should help to make sure no one misses out on any TAPR
51/4* Diskettes_____ ________ 12 information or the PSR.
Software Library Update.........13
In the area of TAPR meetings, a date for the annual meeting in Tucson has been
set, so please mark your calendars now and keep your eyes open for discount airline
tickets to Tucson. The meeting will be the life-blood of any organization. TAPR Project Proposal
held the first weekend in March (5th & TAPR’s future depends on new mem­
Format
6th). There will be a mailing to all bers. New project ideas, software
members in the Fall with in-depth in­ developers, network designers, policy
formation. There will be a proceed­ writers, writers of articles for the PSR,
One of the primary purposes of
ings primed for the meeting, so start and the future board comes from the TAPR is to provide input and support for
thinking ahead about how to write up membership. If you have any ideas on
research, development, and standards
your current project or research. how TAPR can increase membership
for new applications and technology. In
TAPR will also be attending some ad­ in your area, let us know. If you have
order to effectively provide an avenue
ditional ham conventions throughout someone who you think would like to
for new project support we have
the year along with our traditional join TAPR or needs information on the developed an outline for proposal sub­
Dayton visit. TAPR will be at the organization, please contact the office missions. This is based on the earlier
August convention of HamShows held and we will get a PSR and some mem­
submission format horn a few years ago,
at Valley Forge, PA. bership information in the mail. but is much more simplified. The main
To finish this issue off, I want to purpose of the document is to provide
touch on membership. Membership is enough information on the project in
question, so that the board can make an
informed decision. Hopefully the form
The Tucson Amateur Packet Radio Corporation is a non-profit, scientific is pretty much self-explanatory. The
research and development corporation. TAPR is chartered in the State of whole submission shouldn't be more
Arizona for the purpose of designing and developing new systems for packet than about 5 pages total. Proposal sub­
radio communication in the Amateur Radio Service, and for freely dissemi­ missions should be sent to the TAPR
nating information required during, and obtained from, such research. office or e-mailed to Greg Jones
([email protected]). Notification of
The officers of the Tucson Amateur Packet Radio Corp. are:
receipt will be sent as soon as distributed
Greg Jones, WD5IVD President
to the board. The board will then discuss
Bob Nielsen, W6SWE Vice President
the proposal in a timely fashion and pro­
Gary Hauge, N4CHV Secretary
vide feedback. Again, we hope this will
Jim Neely, WA5LHS Treasurer
facilitate project concepts and ideas
within TAPR. If you have any sugges­
The Packet Status Register is the official publication of the Tucson
tions or comments on this format or
Amateur Packet Radio Corporation. Unless otherwise indicated, explicit
process, please let us know.
permission is granted to reproduce any material appearing herein, provided
credit is given to both the author and TAPR. 1. Cover Page
TAPR Membership and a. Name, Address, Phone, Fax, E-
PSR Subscription Mailing Address: mail of project participants,
Tucson Amateur Packet Radio Corp.
(please indicate project leader)
PO Box 12925
Tucson, AZ 85732-2925 b. Title of Project or Proposal
Phone: [phone]
c. Time Period of Project
FAX: [phone]
Office Hours: Tuesday • Friday d. Total Amount Requested
10:00am -3:00pm M.S.T.
17:00 - 22:00 UTC 2. Technical Abstract of Project (short
overview — leps than a page)
PSR Editorial (Only) Address:
3. Research/Project Objectives
Bob Hansen, N2GDE
PSR Editor 4. Research/Project Impact (who this
P.O. Box 1902 is intended for and what is the
Elmira, N.Y. 14902-1902
potential application/service/func-
CompuServe: 71121,1007
tion)
Internet: [email protected]
5. Research/Project Personnel (briefly
describe the participants and what
Packet Status Register (ISSN 1052-3626, USPS 005-419) is published
they will be doing)
quarterly by the Tucson Amateur PacketRadio Corporation, 9991E. Morrill
Way, Tucson, AZ 85749-9568. Membership in Tucson Amateur Packet 6. Technology Transfer (what is the
Radio, including a subscription to Packet Status Register, is $ 15.00 per year potential for something TAPR
in the U.S. and possessions, of which $12.00 is allocated to Packet Status would develop, kit, propose, or
Register, $18.00 in Canada and Mexico and $25.00 elsewhere, payable in publish in the frituie)
U.S. funds. Membership and Packet Status Register cannot be separated.
7. Budget Justification (spreadsheet)
Second-class postage paid at Tucson, AZ.
8. Attach anything else you think
necessary for the proposal.
Page2 Packet Status Register Summer 1993 - Issue #51
Notes from the TAPR have been a few of you who have code-by-touch. The staff, never before
thought that I did not answer your FAX having been able to know what a
Office
on purpose. To the contrary, I have patient in this condition desired, was
stood at the FAX machine and tried fascinated as they heard from the hus­
We are now on the Internet System every combination of numbers that my band what she was saying. Isn’t our
from the office. This is due to die hard telephone directory will offer me on hobby NEAT!
your country, and it has refused to
work of Lou Nigro, KW7H, and Bob Our trip Down-Under went well,
produce results. Your help with this
Nielsen, W6SWE. I’m sure die thanks very enjoyably actually! And we hear
will make me more efficient in getting
should go to additional volunteers, but from our son at West Point that things,
these are the two that interface with me you the material that you are request­ although ten times harder than he ex­
at the office, and I have witnessed, and ing. Also, please do not give me any pected them to be, is settling in, and
am benefitting from their time and “extra” numbers that only pertain to taking on the challenge.
communicating within your own
energies. They have made it so pain­
country. I have no way to know which 73
less that I am thoroughly enjoying it!
they are so they only add to the con­ for TAPR,
Thank you.
fusion! Heather, N7DZU
Those of you that have had
I heard a really nifty story concern­
problems with your Deviation Meter at TAPR/AMSAT DSP
ing morse code a while back that I
the testing point. We have found that
thought you might enjoy reading Project Update
the small PAL chip labeled DEVMTR,
about There is a married couple who
in some cases got programed with a
both are hams, and both proficient at
corrupted master, causing these
The TAPR/AMSAT DSP project is
morse code. The wife found herself in
dificulties. Please return this chip and
well under way. Initial prototypes of
a hospital setting, unable to communi­
we will quickly send you a replace­
the new design will be under test the
cate with the hospital staff, due to her
ment.
first of September. After the alpha­
severe condition, and all the apparatus
For those of you who send us a FAX that she was attached to. The husband testing is completed, an initial beta-
from overseas, please help me with came to her bedside and found that as test run (approximately SO kits) will be
your city and country codes. There he held her hand, she was sending him done in order to test the final design
and allow software developers to test
the units. The TAPR/AMSAT DSP
unit is based on the TMS32QC25, and
TAPR Board of Directors
supports a high-speed serial interface.
Board Member Term CQinpuSetV.fi Internet
A fiill write-up on the design will be
Crawford, Jerry K7UPJ 1994 70521,2356 [email protected]
printed in the next PSR. The DSP
Davis, Jack WA4EJR 1994 72356,441 [email protected]
project is now accepting information
Hansen, Bob N2GDE 1996 71121,1007 [email protected]
from folks interested in participating in
Hauge, Gary N4CHV * 1996 70127,1765 [email protected]
the beta-testing phase. The purpose of
Jones, Greg WD5IVD * 1994 72047,3455 [email protected]
the beta-testis threefold: first and most
Justice, Keith KF7TP 1996 [email protected]
important, create a base of developers
Morrison, Dan KV7B 1994 70541,2374 [email protected]
that can test initial software and begin
Jim Neely, WA5LHS * 1995 73760,3675 [email protected]
to develop future software for the unit;
Nielsen, Bob W6SWE * 1994 71540,2364 [email protected]
second, provide feedback on the kit
and check various operational
Date is expiration of term on Board of Directors.
parameters, and third, allow software
Asterisk indicates member of Executive Committee.
developers to add support to their ex­
isting applications. We are looking for
The TAPR Board of Director members “attend” a meeting, which is continuous­
software developers who need to adapt
ly in session, on a private bulletin board system. The Board encourages input from
their software with the unit or in­
all interested members. If you have an issue you want addressed, or an idea for a
dividuals who have experience with
project you would like TAPR to sponsor, contact any Board member, or drop a
programming assembler routines and
note to the TAPR office.
have some knowledge of DSP to test
TAPR is now accessable through the Internet. You may send e-mail messages the initial software and begin to
(no long files, please) to the TAPR office at develop new software. If you think
taprStapr.org
you are interested, please write the
and to any of the directors at TAPR office stating your qualifica­
eallaignStapr.org tions and the reasons you would like to
participate in the beta-test. Be sure to
substituting their call for “callsign." Also, submittals for Packet Status Register
include information on e-mail, ad­
may be sent to
par9tapr.org dress, and various phone/fax numbers.
Final decisions on beta-tester selection
in addition to the CompuServe address on the front cover. will be made later this year by the
development team.
Summer 1993 - Issue 051 Packet Status Register Page 3
The TrakBox Project issue bug reports, write documentation llow you to set the real-time clock
and so forth. The efforts by the JAs (which is battery backed), your station
were underwritten by JAMSAT, and location (latitude, longitude, and
By Lyle Johnson, WA70XD TAPR was asked to provide a distribu­ elevation) and the keplerian elements
tion channel in the U.S. for anyone for the satellites you are interested in
Have you ever tried to operate an interested in this device. (up to 40 satellites may be loaded, and
OSCAR or RS satellite in low earth the elements may be uploaded in
The TAPR Board decided this
orbit (this is every OSCAR except AO- ASCII in either the AMSAT or NASA
project made sense. TAPR’s ex­
10 and AO-13)? If so, you have formats). Once set up, TrakBox no
perience in bringing useful kits to
probably wished for three or maybe longer needs to be connected to any
Racketeers and Satellite types was a
even four arms. other computer to operate.
good match, so TAPR is now bringing
You have to point your directional this project to you! TrakBox includes a two-line LCD
antennas at the satellites which are display showing the azimuth and
The unit is a sort-of super MetCon,
rapidly moving across the sky. This elevation of a satellite, along with the
with lots of digital I/O as well as an
means updating both azimuth and satellite ID and GMT. The display is
8-channel 10-bit A/D converter. Con­
elevation every minute or so. You have updated every second.
figured as a satellite tracker, it can be
to constantly retune your radio so your
as simple as the board, a source of 12 TrakBox is set up to directly inter­
uplink and downlink stay where they
volts DC to run it, and a connection to face to Kenpro, Emmoto, and Yaesu
belong. And you have to fiddle with
your rotator control box(es) and serial dual-axis rotators which include a
your microphone or keyer, and maybe
port of your computer and let it run. computer interface. It may also be in­
switch antenna circularity.
terfaced to other rotators as long as
Alternatively, you can add a couple
You can do it manually (I have!), simple relays (mechanical or solid-
switches to it, a potentiometer and a
but it isn’t too much fun. stale) are added to the rotator control
2-line 16-character LCD display and
box. It has been tested with the KR500
Now, if you have a PC or clone, and have a totally self-contained unit that
elevation rotator and the CDE/Hy-
if it has available slots, you can always needs no computer at all! (Well, you
Gain series of azimuth rotators (HAM-
buy a Kansas City Tracker and let it need a computer or terminal to initially
M, HAM-II, HAM-IV, TR-44 and
handle the antennas, and possibly the set the real-time clock and load the
TailTwister styles).
radios as well. If you have no slots, or satellite elements, but after that it is
aren’t using a PC, your choices are standalone!) The radio tuning mode has been
more limited. You have to use the tested with Yaesu FT-736, Kenwood
The software can control Kenwood,
armstrong method. TS790, and ICOM 970. It is designed
ICOM, and Yeasu satellite rigs for
to handle any ICOM radio with the
Well, Bruce, SMOTER, decided doppler correction.
CI-V interface (IC275, IC475.
this was no fun and came up with a
IC1275) as well as the Kenwood TS-
program that runs on a MicroMint TrakBox again available
711 andTS-811 models. ICOM radios
Basic 8052 controller. It is based on
from TAPR with the older CI-IV interface can be
W3IWI’s orbit tracking programs
used with an accessory convertor
made popular in the early '80s.
available from ICOM.
Once again TAPR is able to offer
This was a step forward— it didn’t
the TrakBox in kit form. Wewereable An optional tuning mode that util­
require a PC— but it was still expen­
to obtain a limited quantity of the PC izes microphone up/down buttons is
sive and a bit slow.
boards from JAMSAT and have also incorporated. This requires inputs
Sueo, JA6FTL and some others in gathered the necessary parts to make from a modem (PSK or9600 bps FSK)
JAMSAT, started corresponding with complete kits, less case and external and is only for digital operations. This
Bruce via UO-14. They collaborated connectors. has been tested with Kenwood and
and came up with a PC board that was Yaesu radios.
The TrakBox is a self-contained,
much cheaper than the MicroNCnt con­
standalone accessory for use with The price for TrakBox kits is
troller mid included everything neces­
satellite stations. You simply select $195.00, which includes a $25.00
sary for computing satellite obits and
the satellite you wish to track from a donation to JAMSAT for support of
pointing antennas automatically.
front panel control, and the TrakBox the Phase 3D Amateur Satellite pro­
They wrote software for the board in
will steer your antennas in both gram.
’C’ and sped it up considerably.
azimuth and elevation to track the
The quantity available is limited
Jack, WA4EJR, got involved with selected satellite when it is near or
and they will be sold on a first-come,
Bruce and Sueo and became a Beta above your horizon.
first-served basis.
tester of the new tracker. As time went
In addition, if you have a radio with
on, more and more folks became inter­ [If you're in the United Kingdom,
a computer interface, the TrakBox will
ested in this device. AMSAT-UK sponsors a Trackbox
tune your transmitter and receiver and
Users Group; contact Fred Southwell,
To shorten the story, new PC boards correct them for doppler shift
G6ZRU in Brighton for more informa­
were made in December 1991 and a
TrakBox includes a serial port to tion.}
number of us built them and helped
a
Page 4 Packet Status Register Summer 1993 - Issue if 51
two comparators will need to be al­ tune. If this is set too fast, it won't nine
An Automatic Doppler
tered. at all because the de-bounce circuit
Correction Circuit for
will eliminate the pulses!
FSK/FM Satellites How the Circuit Works
LEDs D5 and D2 are included to
The input from the discriminator is
show when die circuit operates.
filtered by Rl/Cl to remove high fre­
by Mike Dorse tt, G6GEJ
quency noise and modulation from the
Construction
DC voltage that the discriminator
Any method of construction can be
(Reprinted from the June!July 1993 generates. This voltage is compared to
used. The prototype was built on a
issue of OSCAR News, published by a reference voltage by each of two
plug-in board, then, a printed circuit
AMSAT-UK.I comparators. The reference voltage for
board was developed for the final unit
The intention of this circuit is to each comparator is slightly different to Veroboard would be adequate. The
prevent the circuit from hunting
provide a simple and reliable method unit was housed in a small diecast box.
of correcting for the doppler shift (and around on a blank channel, or on an A note on components: with the excep­
accurately tuned signal. R2 provides a
for any frequency inaccuracy) while tion of R2, almost any general purpose
you look after the azimuth and/or means of setting this dead band, the can be used. R2 MUST be a multi-turn
elevation. higher the voltage across R2, the larger pot otherwise you will not be able to
the frequency error has to be before
set it with any degree of accuracy.
The circuit will work with any
corrective action will be taken. The
receiver with a logic up/down frequen­
signals from the two comparators are
Setting Up
cy control input, the original was
gated with a slow pulse to prevent the
Apply 12-15 volts to the circuit D2
designed for use with a Yaesu
tuning from going into scan mode. The
should Clash. Apply 12 volts to PI,
FT736R. Access to the discriminator
slow pulse is generated by U4C, R9,
after a short period D5 will start to flash
output (DC coupled) is required. The and C4. R7/D3 and R8/D4 prevent the
nominal discriminator voltage for the and D2 will stop. If this happens, all is
output from the comparators from ex­
736 is about 4 volts. If your dis­ well.andPl should be connected to the
ceeding the logic levels of U4. The
criminator voltage is different from discriminator output and the radio
frequency of this pulse determines the
this, then the reference voltage for the tuned to a blank channel. With R2 set
maximum rate at which the circuit will
to minimum, adjust R3 until both
Doppler Correction Circuit
Summer 1993 - Issue #51 Packet Status Register Pages
LEDs flash intermittently. Then set R2 1TAMSAT Project Status We have prepared an experiment
for a voltage of between 3S to SO mV for this flight; there are two purposes
across it Both the LEDs should now for this experiment: to measure the at­
stay out, or only flash very occasional­ by Paolo Pitacco, IW3QBN titude of the spacecraft using 10 sen­
ly. Tune the receiver to a stable carrier AMSAT-I President sors on two heads, and to measure foe
with the discriminator meter centered, energy emitted from the Sun using 8
and check that the two LEDs are still sensors.
On Saturday, May 8, 1993, all
out. A small adjustment or R3 may be people involved in the first Italian The launch is scheduled for Sep­
necessary. Connect the Up and Down MicroSAT project met in Milan for the tember 1st, from Kourou, on an Ariane
outputs to the receiver. If you tune off
integration of all the satellite modules. 4 launcher, and the launch campaign is
frequency slightly, one LED should
The stacking was performed very well, scheduled to start on August 1st.
flash and the receiver will return to the
and all modules are ready for the first
center of the signal; if it zooms off to a
vibration test. All systems are similar
blank channel, reverse the Up and to the past MicroSATs except some
Down connections and try again. changes were made due to upgrade or
The capture range of the circuit will
depend on the bandwidth of the IF, and
to a certain extent, on the discriminator
characteristics. With the FT736R, the
circuit will pull in a signal with a +/- P R O O E T T O
11.5 KHz offset During tests with UO- ITAMSAT
22, the circuit had the downlink tuned
in with only a few dB of signal-to-
noise to work with, and then kept the
signal perfectly tuned throughout the
pass.
[A limited supply of printed circuit necessity. We have intro­
boards with this circuit are available duced an FM modulator
from AMSAT-UK on a first-come first- with G3RUH encoding
served basis.} into the transmitter
module, and two
RealTtak demodulators (each of two
chips only!) of the same
style into the receiver
by Michael Owen, W9IP module, for 9600 bps
packet. We have changed
The recent announcement by TAPR entirely the CPU module,
of availability of more JA6FIL Trak- designed a 4 MByte static
Box kits is welcome news. RAM, modified foe trans­
mitter module, and remade
RealTrak (by me) fully supports the
the AART.
TrakBox’s “host mode.” In cases
where you want to track satellites that The CPU is now com­
are not in the TrakBox’s memory or if posed of four 2-layer
your want to track the Moon/Sun/noise boards which contain: I/O, CPU and
sources/planets, RealTrak will drive DMA, EDAC (256KB), and RAM-
the TrakBox directly. This feature has DISK (4MB). All boards fit into the
been available in RealTrak for 6 original CPU frame. The transmitter
months and has been thoroughly tested module is only BPSK (twice), no RC, Renew Your Membership!
by JA6FTL. RealTrak also includes a with one unit (TXB) switchable to FM TAPR doesn’t send out con­
built-in dumb terminal for com­ at 9600 bps. The AART is entirely stant reminders when your
munication with the TrakBox’s new, but has the same dimensions and membership has expired. Our
monitor program, uploading of electrical interface as foe original; this only way of communicating
Keplerian elements, etc. job was caused by foe fact that AARTs your expiration date to you, is
Northern Lights Software aren’t available in SMD cases! the date on the address label for
Star Route, Box 60 In the ITAMSAT Project, I am this issue. Please check it and
Canton, NY 13617 responsible especially for the transmit­ renew if required. Your mem­
[phone] (6-9pm) ter module, but I have also designed the bership is very important.
FAX [phone] CPU boards, foe AART board, and foe
transmitter power supply and control
board.
Page 6 Packet Status Register Summer 1993 - Issue #51
DE19K2/9K6 modem that consists
All G3RUH Modems 1994 Annual TAPR
primarily of a CMOS switch. See the
Are Not the Seme Meeting
figure. The labels on the connections
are Kantronics designations. The cir­
cuit-board trace creating the audio path
Robert E. Dubke, KOSIR The TAPR general meeting for
between UIA and CIO must be cut. In
1994 will be held Saturday and Sun­
the new circuit, the 4066 CMOS
[Reprintedfrom the May 1993 issue of day, March 5-6 at Tucson, AZ. The
switch adds a switch in this audio path.
QEX, published by the American site is the same as last yean the Best
The 2N2222transistor provides signal-
Radio Relay League.} Western Inn at the Airport If you have
level conversion for the PTT, which
never attended one of these meetings,
In building a high speed backbone enables and disables the CMOS
you are missing a really interesting and
for packet, one of the nodes was to use switch. The CMOS switch, a 14-pin
exciting experience. Most TAPR
a Kantronics Data Engine with a DIP IC, may be mounted in “dead bug”
“business” is conducted by the Board
DE19K2/9K6 19200/9600-baud fashion, or by straddling a piece of
of Directors, so these meetings are
(G3RUH compatible) modem and an foam insulation material. The 2N2222
devoted almost entirely to technical
ICOM 38A, a 222 MHz band was soldered directly to the PC board
reports from individuals working on
transceiver. This seemed like an easy components. There is very little room
various projects related to packet
thing to implement because the 38A for a separate board for mounting com­
radio. If you are a newcomer to packet
had already been wrung out using an ponents.
radio, don’t be frightened away by
MFJ compatible G3RUH modem.
This modification should work for fears of technical complexity. We are
Wrong! Upon investigation, it was
the Kantronics DE9600 (G3RUH all hams who learn as we go. If you are
found that the 38A’s VCO, used for
compatible) modem and the PacComm working on a project, we hope you will
both transmit and receive modes, was
NB96 series of G3RUH modems as plan to attend and tell the rest of us
being continuously modulated by the
well. Now if only the ice would stay off about it. We will provide oppor­
Kantronics G3RUN modem in receive
the 222 MHz beams, then the back­ tunities for brief progress reports in
mode. This rendered the receiver use­
bone would be perking along FB. addition to more extensive presenta­
less. Of three brands reviewed
tions. In addition to the “contributed
(Kantronics, PacComm, and MFJ),
paper” sessions we have had in the
only the MFJ had the switch circuitry
past, we plan to have a symposium of
necessary to prevent this receive-mode
invited speakers who will present
condition.
several forward-looking topics on
The ICOM 28A/H and 38A/H digital communication. If you know of
models have a common design in this someone (including yourself!!) who
area and contain an audio switch for you would like us to consider for that
the mike. Unfortunately, it is located symposium please let us know. Last
before a low-pass audio filter that must year's meeting featured a valuable and
be circumvented for 9600-baud use. in-depth workshop on Digital Signal
The modem’s transmit audio had to be Processing. We plan to present
inserted at the junction of R4S (IS K another workshop in 1994, and solicit
ohm) and R1S (2.7 K ohm), which was your suggestions as to the topic. Send
AFTER the switch and Alter. The your suggestions for the symposium
receive audio was picked off at pin 9 and/or workshop to Keith Justice,
of IC1 (MC3357P). KF7TP, c/o TAPR in Tucson, or to
[email protected] on internet See you
The solution selected was to add a
at the meeting!!
simple audio switch to the Kantronics
Summer 1993 - Issue #51 Packet Status Register Page 7
)
Shuttle service is available from the
1993 ARRL Conference Valley Forge
airport. Talk-in will be available on the
on Digital HAMSHOWS1993
147.105+ Mhz repeater on both Friday
Communications and Saturday. The Hotel is right off Convention
Interstate 1-275.
Who: All interested in Amateur Radio Hassle-free hotel rooms can be TAPR will be showing at the first of
Digital Communications and Net­ secured by calling 813/879-4800. the 1993 HAMSHOWS. which will
working topics Mention the Conference for a special occur at the Valley Forge Cbnvention
rate is $50.00 a night (single or Center, King of Prussia, PA, August
What A weekend of fun, information,
double), and you can also come up to 21st and 22nd, 1993. TAPR has tradi­
sharing of ideas, etc.
3 days early and stay up to 3 days after tionally attended Dayton each year, but
When: September 10-11, 1993 at the same rate. Do NOT use any other the board felt that this limited access to
(Friday evening and Saturday) Holiday Inn phone numbers other than TAPR to folks who could attend the
this one. This rate is guaranteed only annual meeting in Tucson, or those
Where: Holiday Inn Airport in Tampa,
through August 8th, so don’t wait too who could attend Dayton. This will be
Florida at4500 W. Cypress
long! (You can probably get the rate the first of several conventions that
Why: Why not?!?! after the 8th, but you will be taking TAPR will start to attend in order to
your chances.) raise TAPR’s visibility. We will be
Hosts: The Tampa Local Area Net­
publishing a list of other planned con­
work (TPALAN) Tentative Schedule
ventions in the near future.
Cost Conference registration is Friday 10th:
If you are in the Valley Forge area,
$35.00 prior to August 21, $40.00 4:00 p.m. Registration in hospitality
please plan to attend the convention
after August 21st Registration suite
and stop by and say hello. TAPR will
covers conference proceedings, 7:00 p.m. Birds of a Feather -
be presenting a session on Beginning
catered lunch on Saturday, and as­ roundtable discussions on various
Packet Radio and an Introduction to
sorted items. All participants must aspects of networking; i.e. TheNet,
Digital Signal Processing, along with
take care of all other expenses. ROSE, TCP/IP, etc.
having a full range of TAPR kits,
Address: Send registrations to Saturday 11th: software, and publications for sale.
TP ALAN, 6403 N. Paddock Ave., 7:00 a.m. Registration open We will be planning an informal dinner
Tampa, FL 33614 8:00 a.m. Conference begins Saturday night, so make sure you get
12:00 p.m. Lunch the time and place at our booth. If you
Info: All who pre-register by August
5:00 p.m. Conference concludes would like to help work the booth for
21st will be sent an information
7:00 p.m. Discussions on various the show, please contact Heather at the
packet with up-to-date information
on schedule, etc. Also information “Standards”; i.e. BBS forwarding, TAPR office. For more information
Network routing, message address­ on the convention itself, you can call
on other area attractions will be
sent. ing, etc. [phone] or write to Ham-
Sunday 12th Shows, P.O. Box 3865, Shawnee, KS,
Queries: Queries for information can
Enjoy Tampa, or be a party-pooper 66203.
be sent to “brianlantz@del-
and start back home!
phi.com” or to die above address.
Spouse: Not forgotten! The Hotel is a
couple of blocks from a major mall,
and many other stores where they
can spend the family’s hard earned
money. There are many “distrac­
tions” that can keep them busy fen*
the day.
Distractions: It’s Florida, of course
there are many! Golf course close,
Busch Gardens within 20 minutes,
historic sights, beaches, all within
easy traveling distance. Of course,
there’s Disney World. Sea World,
Universal Studios, and much more
in nearby Orlando, only a little
more than an hour away.
All Conference activities will be
held in the Holiday Inn.
Page 8 Packet Status Register Summer 1993 - issue #51
TNC-2 and the TAPR IN4752CR12 The radio utilized in the repeater is
IN4001 CR7,22 a standard GE MASTR II without any
9600 bps Modem
1N4148CR9,10,11,14,16 modifications to the transmitter or
receiver, with the following excep­
100ohmR16-19
by Don Werts, N7NKJ 470 ohm R34,35,53,54,97 tions: The output from the 9600
modem is applied directly to the trans-
IK Rll, 33,36,46,47,48
Purpose 4.7KR32.98 mitter varactor diode, and the
receiver’s audio is tapped off of the
To document the minimum parts 10K R9,10,12,22,23,26,28,29,30,
discriminator. Both connections are
required to use the TAPR TNC-2 and 49,50,51.67,68.69,71,75,96
DC coupled. The MASTR II's trans­
a TAPR 9600 bps modem in a full- 27KR25
mitter key-up time has been modified
duplex packet repeater. The TNC is 47KR13
such that it reaches full power in less
used with the standard firmware (vers. 100K R20.21,24,27, 31,37,43,64,
than 7 milliseconds. This last item was
1.1.8) to supply the repeater ID func­ 72
not a requirement, just a successful
tion. 1 Megohm R83
experiment! This particular MASTR II
2N3904 Ql, 4,6,7,13,15 transmitter is capable of 60 watts out­
Modifications (Cuts and
2N3906 Q5 put, which is adjusted down to 30
Jumpers)
VN10KMQ10 watts.
(I don’t know the PWB revision
7805 Regulator Q3
level, some boards may not need The repeater is installed in Western
Crystal Y1
jumpers 1 and 2.) Washington a a site on Baldi Moun­
U1CD4040 tain (4200 ft elevation) northeast of
1. Add a wire from the ground trace
U3LM324 Enumclaw. It has been “worked” from
near U9 (74HC14) to its pin 7.
U474HCT393 as fa away as Vancouver, BC, to
2. Add a wire from the ground trace U5 74HCT374 South of Olympia, and into Eastern
near Q3 (7805) voltage regulator to U6 2764 EPROM, Stale Machine Washington. For those of you in the
its middle terminal. U7,9,10,14 74HC14 area, feel free to use the repeater, it
Ull 74HC107 transmits on 146.98 and receives on
3. Connect pin 11 of U3 to a close-by
U12 74HCT139 146.38 MHz. The call is N7NKJ-8. To
ground trace. We found that we did
U13CD4066 the best of our knowledge, this is the
not deed the -5 volt supply to run the
U21Z80SIO first full-duplex repeater with bit
RS-232 port at 4800 bps. You may
U22Z80ACPU regeneration a 9600 bps in the Pacific
need to verify this for your applica­
U23 27C256, TAPR 1.1.8 Firmware Northwest.
tion.
1124,25 6264LP or 43256L
4. Cut jumpers on J4, the modem dis­ Future Projects
Miscellaneous hardware consisting
connect header, at terminals 11 and As this repeater is at an elevation of
of IC sockets, headers, and jumpers
12. 4200 ft. in the Cascade mountain
have been omitted from this parts list,
range, it is usually inaccessible from
5. Install a jumper or shorting block on and it is left up to the builder’s
December to ealy April; we’re con­
JMP12 for the A13 address line, if preference. Please note: to install the
sidering using METCON-1 to access it
you’re using the TAPR firmware in 9600 modem onto the TNC-2 does re­
via the9600 modem, or through a con­
a 27C256 EPROM. quire the 20 or 26 pin mating connec­
trol link. We want to monitor the trans­
tor, or other suitable means of intercon­
mitter power out, tire reflected power,
Parts List for the TNC-2 nection (i.e., a short ribbon cable).
the AC power, the backup battery
TAPR TNC-2 bare printed circuit
Note: Q13 and its associated parts status, and the outside temperature and
board
were installed to facilitate initial wind speed. METCON-1 looks like a
10pfC51 checkout. If you do not install this perfect fit for us.
60 pF Trimmer C47 capability, R68 is still required.
Congratulations to all the people a
100pFC61
220 pF C60 Application TAPR for making these fine products
available, and consequently making
.01 uFC2,19,24,59 The TNC-2 has been running with
this project successful and AFFOR­
.1 uF Cl, 6,13, 14, 15. 17, 21, 23. the TAPR 9600 bps modem for two
DABLE!
25-30,37,40,41,48.49,50,61,62 months flawlessly. This is an excellent
1 uF C20,58 combination of products for this ap­
10uFC8,18,22,31 plication, certainly very cost effective.
100uFC16 This configuration does not support
1000 uF 02 any 1200 bps operation! The modem
was built with the optional internal
10uHLl,2
clock and bit-regenerative circuits.
LEDs CR17,18,19,20,21 This provides a frill-duplex regenera­
tive repeater for 9600 bps packet.
1N4746CR1
IN754 CR8
Summer 1993 - Issue #51 Packet Status Register Page 9
Forward Error Compute power is now more readi­ term S/NoB, where No is the equivalent
ly available. FEC is put to good use in receiver noise power density in watts
Correction
the Amateur world for links with a very per hertz and B is the channel
narrow margin, as CLOVER does on bandwidth, as before. This form points
by Harold E. Price, NK6K HF. It can also be used when the link out that the received noise power is
margin would be good if not for the proportional to the receiver
Phil Kam, KA9Q
presence of an interfering signal, as is bandwidth; a wide receiver “lets in”
the case in Southern California with more noise than a narrow one.
[Reprinted from the June 1993 QEX,
military radar on 70 cm. You can move
published by the American Radio If we rewrite Shannon’s equation to
away, as I did (it was one of the
Relay League.] use parameters more commonly used
reasons, anyway), or you can try to do
with RF modems, we get:
There are several ways of attempt­ something about it, as Phil Karn,
ing to send perfect data over imperfect KA9Q, explains below. Phil recently C = B log2( 1 + (Eb /No) x (C/B))
RF links. One is ARQ, Automatic moved to Southern California. He
where
Repeat Request As is done in AX.25, spoke on FEC at this year’s TAPR
enough information is added to the meeting, and has provided the sum­ Eb = received energy per bit, joules
data for the receiving station to deter­ mary of that talk that appears below. (watt-seconds)
mine whether the data was received
No = equivalent received noise den­
correctly. If it was not the computer KA9Q on FEC
sity, watts/Hz
automatically requests a retransmis­ Forward Error Correction (FEC)
sion. This is more efficient than the use has been around for a long time, but The ratio Et/N0 is the figure of
of error-correcting codes when a data only recently has it become practical merit for all digital modems; the lower
error is notlikely to occur. Itis required for radio Amateurs to experiment with we can make it, the less RF power we’ll
if the data must be received perfectly. it using low cost computing equip­ need to send data at a given rate. Now
ment suppose we have infinite bandwidth
Another method is FEC, Forward available. How low can we make
Error Correction. In this scheme, you Much of the research into FEC
Eb/No?
assume that there will be errors, and/or came from NASA’s need to make the
the other side of the link can’t send an most of low-power, very-long-dis­ The answer is -1.6 dB, the “Shan­
acknowledgment. FEC sends enough tance communication links from non bound.” It is theoretically impos­
additional information along with the planetary probes. The specific techni­ sible to go lower. But this is still a lot
data to allow the receiving stadon to que I will describe later was used for lower than what we see in practice. The
best RF binary modems (BPSK) re­
detect errors and correct them. This the Pioneer 10 and 11 probes that were
does not guarantee perfect data recep­ launched in the middle 1970s, becom­ quire S/N ratios of at least 10 dB for
tion; the original data cannot be ing the first man-made objects to es­ good performance. Less efficient
recovered if too much information is cape the solar system. Thanks in part modems (e.g., FSK) require at least
13-14 dB, and the very worst
lost. Perfect data communication re­ to FEC, these probes are still tracked
quires ARQ along with FEC. by NASA’s deep-space network. (AFSK/FM) may require 20 dB or
more. And these figures are inde­
Although an FEC mode has always Related (though different) schemes pendent of the receiver’s bandwidth;
been available in AMTOR, FEC hasn’t were used on later deep-space mis­ once you have enough bandwidth,
been used with packet radio up to now sions, such as Voyager 1 and 2. more doesn’t buy you anything.
for several reasons. First, good FEC is
All forward-error-correction
Unless you use FEC. This is the key
computationally intensive and is
schemes apply the same basic principle
to trading off bandwidth for power.
usually implemented in hardware.
from Shannon’s communication With it we can approach (but not reach)
General purpose CPUs haven’t be­
theory. According to Shannon, the
the Shannon bound. In practice, it’s
come fast enough to handle high data
capacity of a noisy, band-limited chan­
fairly easy to take the required Eb /No
rates until recently. Second, pure FEC
nel depends on both its signal-to-noise
for PSK to 4-5 dB, but 2 dB is about
adds a fixed amount of overhead. Even
ratio and its bandwidth:
the practical limit with known techni­
if the redundant information is not
needed, it is always sent On most C = B log2(l + S/N) ques. Still, this is quite a bit better than
the 10 dB required for PSK without
VHF/UHF links, overhead caused by
where
noise-created error retries is less than FEC.
the fixed overhead of common FEC C = channel capacity, bits/sec These gains, called “coding gains,”
codes. Most metropolitan area retries B=channel bandwidth, Hz are quite real. If the FEC in use has a
are caused by collisions. coding gain of 5 dB, you can drop your
S = received signal power, watts
Finally, the ubiquitous TNC, with transmitted power (or antenna gain) by
its HDLC chip, hard CRC checking, N = equivalent received noise power, 5 dB and still transfer data at the same
and AX.2S protocol, does not lend it­ watts rate as before! Anyone involved in,
self to easy FEC upgrades. We’ll ad­ log2 = base 2 logarithm say, DXing or moonbounce operation
dress the fust of these problems in this knows that generating large amounts
month’s column. Sometimes the signal-to-noise of effective radiated RF power is ex-
ratio, S/N, is replaced by the equivalent
Page 10 Packet Status Register Summer 1393 - Issue 051