[amsat-bb] PSAT Elements are 6 minutes early

Robert Bruninga bruninga at usna.edu
Sat May 23 14:51:42 UTC 2015

Today, (over USA) I am finding satellite to be 8.5 minutes behind the
ULTRAsat3 TLE.  And get a very good match.  I am listening to the PSK31 *FM*
downlink on 435.350 +/- 5 KHz and swinging the beam and watching Doppler to
confirm I am tracking well.

But Nico (below) sees it on time in Europe.   I cannot explain the
difference... I am using the elements with an EPOC of 15 140.6701389 (shown
below) which were released at separation.  There have been no updates yet.
As soon as I get them I will post them.

I did just turn on 3 USA and 3 European packet bulletins.  And adjusted the
MA spacecraft counter so that the right bulletins will come on over the
right continents.  DIGI will remain off since PSK31 is working so well!

Bob, Wb4APR
-----Original Message-----
From: Nico Janssen
Sent: Saturday, May 23, 2015 10:24 AM

Yesterday and today I performed detailed doppler measurements on high PSAT
passes, both on 70 cm and on 2 m.
I found that yesterday the satellite was 10 seconds early and today 14
seconds early, compared to the ULTRASat3 TLE set.

I wonder why you think it is 6 minutes late. Maybe you were confused by the
ASCII telemetry transmissions on 145.826 MHz of UoSAT-OSCAR 11, which passed
about 6 minutes after PSAT?


On 2015-05-22 20:21, Robert Bruninga wrote:
> I am finding that PSAT is 6 MINUTES behind the predictions of the
> previously provided original Launch TLE :
> 1 99993U          15140.67013889  .00040043  00000-0  10235-2 0 00009
> 2 99993 055.0004 339.9238 0251027 182.3314 074.3075 15.12517086000014
> So until I get new ones.  Just point at AOS and wait 6 miuntes.
> Also, I had said not to TX PSK31 on the 10m u plink until you heard
> the downlink.  Well, that was dumb advise, because the transponder
> does not come up unless it hears PSK31!
> So the new rule is, Listen first.  If not heard, TX anyway.  If not
> heard then, Fix your problem, and try again?
> We don’t know how the power budget will work out.  So all we can do is
> watch.
> Bob, WB4APR
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership.
> Opinions expressed are solely those of the author, and do not reflect the
> official views of AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb

More information about the AMSAT-BB mailing list