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 Japan. 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
Cheers 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 Willow
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!)
73!