Re: Highest data rate achieved in the Amateur Satellite Service
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!
Hi Jim and Ken,
As far as I can recall, the only high speed packet capable amateur bird operational and in orbit is AO-51. We've run it at 38k4 recently. It works OK. Other birds have been in orbit and operational years ago (you can google them--I'll leave somebody out or get it wrong if I try to list them (KO-23? MO-36? UO-22?). I think I've worked them all. Candidly, AO-51 doesn't run 38k4 as well as the older birds used to--and there is no apparently reason or setting to tweak to make it awesome.
AO-51 has the potential to run at 57k6 and even 76k8--but I honestly don't know if it has ever been tested in-orbit since launch. Keep in mind the birds normally receive at 9k6 only (although in theory they can go higher), so most hams are 9k6 transmit capable, but not any higher (and the TNC modems are usually configured this way, as well--38k4 receive, 9k6 transmit).
Going from 9k6 to 38k4 requires more "oomph" from the satellite in terms of output power in order to copy it (well, more signal into your receiver is needed the higher you go due to the width of the signal, etc. ).
Personally, I have two rigs with Symek boards (see below) that should in theory be capable up to 76k8, but the fastest TNC modems I have in the shack are set to 38k4. So, I can't even experiment at those speeds without a substantial investment.
Yes, you can modify an IC-910 for high speed packet. The mod to the TS-2000x was MUCH easier than the TS-790 (which didn't even do 9k6 out of the box!).
My "dream" is for a Flex 5000 with the U/V modules in it, and THEN for some clever software decoders to be written at 38k4 or higher so no TNC is required--it's all done in software!!!. But then again, there is only 1 bird that can run at that speed, and it's a rare occurrence....so it's not worth spending money I don't have for software decoders that don't exist for one aging satellite...
I'd like somebody to comment on P3E and what it is likely to do packet-wise....I know the info is out there, but it's not in my brain :)
73!
Mark N8MH
______________
Hi,
I would be interested to know what the highest data rate achieved from an amateur satellite is/was. I seem to recall some sats using 38.4K but not sure if this is true, or how successful they were.
I'm guessing that use of 'normal' amateur radio rigs, eg ICOM 910 isnt really practical for these higher data rates (although I know of an add one unit from Symek, which will provide higher bandwidth from the 910, and other radios).
Is anyone planning to use a higher data rate?
I'd be interesting to read any comments folk might have.
73 Jim G3WGM
On Thu, Dec 2, 2010 at 6:23 AM, GW1FKY@aol.com wrote:
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!
Mark L. Hammond [N8MH] _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
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Mark L. Hammond