Observation 191862: MEMSAT (99962)

Regarding Observation 191862

Any ideas what this is? I don’t recall vetting this one as Bad either.

I vetted it as bad as I think this is another satellite. Since this was an observation on my station I can also vet it.

Did any other stations get the same signals?

Ah, that makes sense. I didn’t realize that. I’m sure you are right - this is the first of this kind of signal relating to MemSat. I’ll keep periodically scheduling observations in case it shows up again. But without a radio signal, we don’t know which NORAD ID it has, so I guess the possibility of observation error such as this will grow.

Just got these two MemSat observations, both from the same station 37 - DL4PD, about 3 hours apart:


However, I suspect that the signal is most likely 28895 - CUBESAT XI 5 which has an AFSK1k2 transponder that is only 5kHz lower than MemSat and is overlapped with it right now for this station:

But I haven’t found any observations of CUBESAT XI 5 which look like this.


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Good sleuthing Alan!

From my July 15 bandscan I got these objects at frequencies within 50kHz of the nominal MemSat frequency (NORAD ID, frequency in MHz):

43466 437.301125
36799 437.304750
35935 437.323594
42792 437.325625
39417 437.356875
42736 437.371625
41935 437.372563
40968 437.376562
39446 437.384687
33499 437.386781
40377 437.397688

None of these objects was above the horizon at DL4PD at both times.

The few observations of the AFSK transmitter of 28895 CUBESAT XI 5 I could find all look different from the signals DL4PD caught, so your identification certainly looks tentative.

I’ll try to operate station 40 in scanning mode again this evening to see if the signal pops up and can be linked to a TLE.


I’ve got bad news for you all:
Some calculations and the fact, that there is a CW ID audible in the recording shows:

437,350 MHz / 3 = 145,78333 MHz

Which is close to the third harmonic of DB0WAs repeater downlink (145,7875 MHz).
CW ID also matches.


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Can’t argue with math (Or call signs)! Next time I’ll listen to the audio :slight_smile:

Mystery solved!

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We’re all learning - I might need a better receiver to do more quality stuff at my station.

This may actually be something on the ground.

On a direct overhead pass, the Doppler compensation will adjust for the satellite coming towards and then shifting over to going away as it passes directly overhead. A ground-based interfering signal will look like an S going low to high.

On a pass that skirts the ground station, the Doppler compensation will adjust only slightly for the satellite coming towards and then gradually to going away as the satellite is “going around” rather than overhead. I believe a ground-based interfering signal will look like a C.

I would love to understand the math behind the Doppler compensation better. It may be possible to identify and reject signals that are specifically ground originated signals.