CAMSAT XW-3 (CAS-9) amateur radio satellite launch on 2021-12-26

Hello OM,

The CAMSAT XW-3 (CAS-9) amateur radio satellite will be launched at UTC 03:11:31 on 2021-12-26 , and will be deployed at 98.858° east longitude and 28.413° north latitude at UTC 03:35:58, location close to Western Australia.

Radio amateurs will receive CW beacon and GMSK telemetry signals approximately 38 seconds after the satellite is separated from the launch vehicle, and then the linear transponder will be put into use after approximately 49 seconds.

Attached is the launch schedule.
XW-3(CAS-9) Amateur Radio Satellite Launch Time Sequence.pdf (1.5 MB)

Two-Line Orbital Element file:

1 99999U          21360.14997609  .00000032  00000-0  10363-4 0 00007
2 99999 098.5836 072.3686 0004232 307.2415 261.3002 14.38559758000156

Alan Kung, BA1DU


CAMSAT XW-3(CAS-9) satellite has been installed on the CZ-4C Y39 launch vehicle at the Taiyuan Satellite Launch Center in China, and related work is in progress as planned.

If all goes well, the satellite will be launched on December 26, 2021 03:11:31 UTC, it is piggybacked on the rocket with governmental primary payload ZY-1(02E) earth resources satellite. The orbit will be a circular sun-synchronous orbit with an altitude of 770.1 kilometers and an inclination of 98.58 degrees, the running cycle is 100.14 minutes.

Attached is the user’s manual of XW-3 (CAS-9) satellite for radio amateur.

XW-3(CAS-9) Amateur Radio Satellite User’s Manual V1.0.pdf (902.3 KB)

Alan Kung, BA1DU


Can someone in the SatNOGS team add CAS-9 in the list of satellites?
Thank you!
/Lars SM0TGU


The satellite is added in DB with temporary NORAD ID 99525. SatNOGS DB - XW-3

Will be available in Network for scheduling in the next couple of hours, scheduling should be done after deployment at 2021-12-26 03:35:58 UTC.


XW-3 is received firstly around at 03:35:50UTC by stations " 24 - Binar-SatNOGS" in observation 5201187 and by “158 - Picosat Systems - UHF” in observation 5201188.

Several station have also received it since then on both CW and GMSK frequencies. The GMSK signal seems to be drifted ~4KHz, for example in observation 5201271. I’m going to add this drift in DB.


Low elevation pass was part of my problem, but was not able to decode the 4k8 telemetry packets as there was strong CW on the ‘right’ edge of the downlink w/ the same doppler track. Does anyone know what object that is from?

I can copy some of the CW
camsat camsat

That’s interesting… wondering now if the extra signal at the right is the GMSK signal or the CW you observed in observation 5201271 and some others.

Given that it was the only amateur satellite on this launch, I guess the signal should be from the satellite but we don’t expect something on that frequency.

EDIT: I’ll keep watching it as there are some GMSK observations in the next minutes.

Wow - good to know! Decoding the 4k8 is going to be tricky if that other signal is permanent.

Hopefully on a higher pass the 4k8 signal will be strong enough to decode reliably even with the secondary signal there.


Here we have some decoded data SatNOGS Network - Observation 5201272 with the CW signal.

EDIT: interestingly we don’t have any drift on the frequency on these… maybe I’ll need to revert my changes but I’ll wait for the next observations.

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It tracked that preliminary TLE extremely well for me.

Indeed, I’ve also checked if there was any other known satellite on this frequency and I didn’t find anything. Let’s see… :slight_smile:

After a better look I decided to revert the drift I added in the GMSK trasmitter in DB. It seems that something else going on, so until we find out I’ll keep the initial frequency for the GMSK transmitter.


We have some first TBA(to be assigned) TLE sets from

1 50465U 21131A   21360.33701581 -.00000045  00000-0  00000+0 0  9997
2 50465  98.5950  72.5542 0002589 235.2111 220.7060 14.37616626    34
1 50466U 21131B   21360.46108061 -.00000045  00000-0  00000+0 0  9996
2 50466  98.5947  72.6792 0003657 306.1068  72.4667 14.38425641    47
1 50467U 21131C   21360.46481547 -.00000059  00000-0  00000+0 0  9995
2 50467  98.6377  72.7561 0117429  65.8633   0.0572 14.63830187    57

OBJECTS A(50465) and B(50466) seems to fit. We are going to follow OBJECT B(50466) as it seems to fit better.


Another low pass here 1500utc on 26-Dec, but thankfully that rogue CW on the right edge of the 4k8 telemetry beacon is gone!

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Could you reach out to Alan and ask for the endianess? There seems to be some issue during decoding and I am not sure what raises it.

Details will follow once I’ve finished an initial decoder…

I had the CW but the station to the East of me did not have the CW. Same pass and the ground stations are fairly close.

For anyone using Direwolf to decode CAS-9’s 4k8 data stream, please don’t make the mistake I did.

This is not AFSK, it’s baseband data. So, there should be a line in your .conf file like this:

MODEM 4800 0:0

… thanks to the gift of a strong recording from N6RFM, I was able to test my setup. Without the ‘0:0’, no decodes!


Well, got my first ‘live’ decode on the 0350utc pass (27-Dec-2021) over the U.S., but not easy with the strong CW back alongside the stream of packets. Can’t tell from this picture but at times the signal strength of the CW was more than double the magnitude of the 4k8 packets.


I just reached out to Alan about the apparent difference on some of the GMSK packets we have received.

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