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

[Mark L. Hammond]

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 at 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]
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-- 
Mark L. Hammond [N8MH]