[amsat-bb] Re: Highest data rate achieved in the Amateur Satellite Service

GW1FKY@aol.com GW1FKY at aol.com
Thu Dec 2 03:23:00 PST 2010

Hi Jim,
You are quite correct  48K data rates have been used on amateur  satellites.
I trust that it is OK with Mark Hammond but here is a copy of a recent  
posing on the BBS regarding experiments to be carried out on AO -51.
James Miller was I recall very involved in the use of higher data rate  
exchange and you might find some information posted on this.     Another good 
source are the listings of the operational frequencies and  modes
of operation that are posted on a number of well known web sites including  
The main problem and concern of course is the need to modify equipment to  
be able cope with these higher
rates.  As you state modems are available but the inclusion in the  
equipment can be quite costly and i am not sure about the validity of warranty  if 
you do make these additions.
Another concern is that with the LEO's tracking and the doppler  shift are 
a very significant factor , however
with such short pass times of course the higher rate of date exchange  is a 
very valuable asset especially
with pictures
Ken de GW1FKY
 Hello All,

Just a reminder that we'll be running a few days of  38k4 packet
beginning Sunday afternoon/evening until Thursday  afternoon/evening,
as per the schedule below.  Note the voice repeater  will be OFF.

Please keep in mind that receiving packet at 38k4 requires  more than
your "stock" FM receiver and TNC.  Generally speaking, folks  are using
a Symek board installed in their satellite radio to tap the IF  which
is then fed to a high speed TNC.  Other options for a receiver  include
a PCR-1000/1500/2500 in FM mode with filters set to 50 kHz  (NOT
Wide-FM)  (I think that's the right filter width).

Please  remember Douglas Quagliana's KA2UPW soundcard decoder (as
presented in the  AMSAT Journal a few issues back) that can be
downloaded here:   http://www.quagliana.com/     Look for Willow  and
Sabins.    I suggest you get the software and test it out at  9600
before you attempt 38,400, so to become familiar with how it  works
with your receiver.   It does work at 38k4--but remember you  must have
an appropriate receiver!

It is possible to use some of the  SDR stuff I'm sure, if you record
with your SDR software and play back  through KA2UPW's Willow program.

I have a few options in my shack, as  I've been running 38k4 since the
good old UoSat days:

Receivers  capable of 38k4 (up to 76k, actually):
TS-2000x with Symek IF  board
TS-790A with Symek IF board
Icom PCR-1500

For  decoding:
Paccomm Spirit/Sprint-2 Satellite TNC models with 38k4 filters  installed

My preferred combination is the TS-2000x with Symek  IF board feeding a
Pacomm Sprint-2 satellite model.  I seem to get the  best performance
out of this combo.

Here's a reminder of the  schedule:

November 14 (late UTC)
38k4 Baud PBBS Operations,  L/U
Uplink: 1268.705 MHz FM at 9600 baud
Downlink: 435.150 MHz FM at  38,400 baud

November 18 (late UTC)
FM Repeater, L/SU
Uplink:  1268.705 MHz FM (no PL tone)
Downlinks: 2401.200 MHz FM *and* 435.300 MHz FM  (at low power!)

Mark L. Hammond  [N8MH]
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