[amsat-bb] Chinese Lunar sats

[Edson W. R. Pereira]

Jean,

I suggest usign the live Ubuntu ISO image with gnuradio and the necessary
OOT modules for monitoring the GMSK signals. While installing gnuradio and
the OOT modules manually can be done, it takes some effort. Running the
live image is much easier. You do need a fast computer with at least four
CPU cores  to be able to run all the flowgraphs.

I had some difficulties with the doppler correction in my setup during the
first pass. The predictions seemed off and I had to manually adjust the
frequency offset to get the signals into the demodulators' passbands. Once
that was done, I could decode the GMSK telemetry from both satellites up to
64000 km. Above 64000 km, my small antenna was no longer enough. I will get
a better antenna ready and will try monitoring again over the weekend.

73, Edson PY2SDR




On Tue, May 22, 2018 at 1:21 PM, Jean Marc Momple <
jean.marc.momple at gmail.com> wrote:

> Nico,
>
> I have been trying to capture the signals from the both Longjiang sats for
> the past 2 days.
>
> On Monday it seems that I receive a carrier on the right frequency but was
> not able to confirm that it was from Longjiang 1.
>
> I used the initial Keppler’s and now using Celestrac in SatPC32 which
> seems to be OK when comparing with N2YO ele/az. I have been monitoring on
> the announced FX and having also JT4G “on” for about this evening without
> any results.
>
> For sure I am doing something wrong but cannot figure it out due to the
> lack of information.
>
> Also, trying to get a decoder software for the GMSK telemetry is quite
> difficult for a non-IT geek, I don’t have clue how to have the published
> GITHUB decoder to work on my Windows computers…
>
> Here we are this side.
>
> Quite frustrating that the communication is not that good, as if the
> project team want the maximum of feedback and TLM they should provide a
> minimum of info. Just a personal opinion.
>
> Anyway will try hard to receive these birds as a real opportunity for HAM
> to learn more on outer space com, if anyone can help and share,
> particularly the guys who already decoded the birds, it would be more
> welcomed.
>
> 73
>
>
>
> Jean Marc (3B8DU)
>
>
>
>
>
> > On May 22, 2018, at 5:03 PM, Nico Janssen <hamsat at xs4all.nl> wrote:
> >
> > After their launch on 2018-05-20 at 21:28 UTC, LJ 1 and LJ 2 were
> > maneuvered onto a track to the Moon. Several amateurs received
> > telemetry from the satellites. But now LJ 1 appears to encounter
> > problems.
> >
> > Quoting Wei BG2BHC:
> > "Can you help to find amateurs in the US to help to monitor DSLWP-A
> > on 435.425 and 436.425 now?
> > We lost the contact of satellite A on S band after an orbit adjustment.
> > We just tried to switch on UHF, but we don't know if it works or not.
> > The sat is just above South America.
> > If it works, 435.425 should be 500bps GMSK and JT4 alternately.
> > 436.425 should be 250 bps GMSK.  Bothtransmit once in 5 minutes.
> >
> > Thank you very much!
> >
> > Wei"
> >
> > 73,
> > Nico PA0DLO
> >
> > On 22-05-18 12:15, Mike Seguin wrote:
> >> Any word on the two Chinese microsats LongJiang 1 & 2?
> >>
> >
> > _______________________________________________
> > 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
>
> _______________________________________________
> 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
>