[amsat-bb] PSK31 on PSAT-1 (was elbow room)

Robert Bruninga bruninga at usna.edu
Sat Nov 7 03:58:01 UTC 2015

> How about a PSK-31 Cubesat within VHF/UHF?

Because the 6000 Hz and 18,000 Hz of Doppler change on VHF and UHF simply
cannot be done with PSK31 that requires tuning accuracy of +/- 1 Hz.  By
using ten meter uplink and FM downlink we eliminate the downlink Doppler
and reduce the nominal Uplink Doppler on ten meters to an average around 1
Hz/sec for the lower portions of most passes.  Bob, WB4aPR

> Not many of us have a 10m dipole… as part of our satellite setup

A simple portable fishing pole with an 8’ piece of wire on and another 8
foot counterpoise laying on the ground would make a great ten meter
vertical for PSAT-1 PSK31 uplink.  (Sorry though, that it takes more than 5
watts due to cramming an HF antenna on a 6” cubesat).


*Sent:* Tuesday, November 03, 2015 10:43 PM
*Subject:* Re: [amsat-bb] AO-85 Rudeness (elbow room)

> I like to see the 10m uplink "arrow" approach :-)

> While PSAT-1 is a nice "proof of concept for PSK-31"

>  in reality it does nothing for the portable operator and

> that is what the original post is all about. ….

> Using PSK31 is a great idea, the 10m uplink is the real issue

> for the non-use of PSAT-1. Should I say "fatal flaw"?

> Not many of us have a 10m dipole ready as part of our satellite setup

> (stationary or mobile for that matter).

> It is time that we move on and promote digital modes on

> frequencies that are actually used within the allocated satellite

> bands and even better on higher bands where we have allocations

>  and we don't use them.

> How about a PSK-31 Cubesat within VHF/UHF?

> ... and leave 10m on the ground where it belongs LOL :-)


On Tue, Nov 3, 2015 at 4:27 PM, Robert Bruninga <bruninga at usna.edu> wrote:

Take a break from the congestion.... come to the wide open multi-user
wideband transponder on PSAT-1.  Downlink is good on a handheld arrow on
435.350 MHz FM.  It should be able to support dozens of simultaneous full
duplex QSO's in the PSK31 waterfall.

Just pick an empty spot and key your TX solid for the full 8 minutes of the
pass on your 10 meter PSK31 uplink 28.121 MHz..

To run fullduplex, just run two copies of your favorite PSK31 software.  One
receiving the FM downlink and the other transmitting on the SSB uplink. Even
better is to run Andy K0SM's TX-only uplink client that pre-adjusts for
Doppler so everyone can decode you with no adjustments.


Text with everyone all at once.

Bob, WB4aPR
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