[amsat-bb] PSAT- transmission sequence

David G0MRF g0mrf at aol.com
Wed May 27 13:54:23 UTC 2015

Congratulations Bob and USNA on another successful spacecraft.

I listened for the first time this morning and could hear the beacon and transponded PSK31 without any trouble.

But I was not expecting the 435.350 carrier to stop every now and again. 

What determines if the carrier is on or off. - Beacon timing.- OK, but is the transmitter also PSK activated in someway? Or is it a timer.
Very nice for saving power.


David  G0MRF
-----Original Message-----
From: Robert Bruninga <bruninga at usna.edu>
To: AMSAT BB <amsat-bb at amsat.org>
Sent: Sun, 24 May 2015 17:58
Subject: [amsat-bb] PSAT Status (day 4)

PSAT  PSK31 435.350 MHz FM downlink is full quieting with 6 bars using a
UHF Yagi.

But we have not seen any users other than those using the 28.120
channel on HF normally.  We welcome people to experiment with it.
within the 28.120 to 28.123 MHz ten meter passband will be
uplinked and heard
on the 435.350 MHz downlink.

The Naval Academy's PSAT seems healthy with
plenty of power (we are
keeping the APRS digipeater off to allow max power for

PSAT 's radio and packet system are a simple $250 APRS
http://www.byonics.com/mtt4b sent to space.  The PSK31 transponder is
single 3.4" square circuit board made by Brno Universtiy in the
Republic.  The CPU for controlling bulletins and timing is a
Parallax Basic Stamp.

PSAT is actually only about a 1U cubesat but in
a 1.5U package since the
flight was available and it gave us more power for our
cells.  We are using standard silicon that are only half as
efficient as
multi-junction cells, but only cost 1% as much.


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