Vega VV16 launch (2020-09-03)

vedurk · September 5, 2020, 9:30pm

I included the CW transmitter suggestion for TTU100.

Could it be that the TLE was calculated with one point (from the pre-launch vector)? As much as I have seen with my limited experience then one point SGP4 calculations can get inaccurate relatively quickly.
But in any case, to put it all into perspective, it seems that the satellites are slowly drifting apart. Even two-body analyses with post-launch vectors give some perspective in this regard. The distance between the red and the blue is ~1000 km on ground track (might be ~20° pointing difference on ground) and ~1800 km between the greens:

fredy · September 6, 2020, 4:23am

A quick update… TRISAT was received again.

For AmicalSat there are new TLE from R4UAB that fit pretty well the received signals as shown in the next images (Observation 2791859 and Observation 2791861):

AMICAL-SAT_R4UAB_0509
1 99990U          20248.92756215  .00000000  00000-0  54130-5 0    05
2 99990  97.6582 322.0266 0002774 190.2963 136.9539 15.09845002    01

fredy · September 6, 2020, 4:36am

Much appreciated, suggestions have been approved.

Unfortunately I don’t know that, maybe someone else.

That’s true, but usually this means couple of days for the altitude of these satellites, if the TLE are accurate. As we have preliminary TLEs I can not guarantee how fast they will get inaccurate.

Just to mention here that some individuals running another kind of observation with a tool named strf (GitHub - cbassa/strf: Radio Frequency Satellite Tracking). With this tools they scan (create a kind of waterfall) for a wide frequency range and for a long period (that covers before and after the expected pass) that would be enough to locate satellites that have transmitted even if the TLE are not so accurate. Here is an example of such observation.

PS we are very active in our matrix/irc channel about this deployment, feel free to join us.

cgbsat · September 6, 2020, 12:07pm

Here’s an updated AMICALSAT TLE based on STRF measurements over 3 passes from station #40.

1 99836U          20250.45833333  .00000000  00000-0  50000-4 0    08
2 99836  97.4424 323.6241 0002604  52.7026 309.9879 15.09885722    04
# 20200905.94-20200906.48, 21 measurements, 0.018 kHz rms

This TLE is determined by propagating the pre-launch 74002 TLE to today, and then using Doppler measurements to fit the mean anomaly, RA of the ascending node and the mean motion.

R4UAB · September 6, 2020, 3:39pm

Good afternoon, write me an email: r4uab@r4uab.ru

s59mz · September 7, 2020, 2:15pm

I contacted TRISAT team and got their newer TLE and some parsed data from their satellite.

1 26405U 00039B   20248.00000000  .00000000  00000-0  50000-3 0  9993
2 26405 097.5184 321.1086 0004082 014.9034 309.7984 15.09899686000000

The data can be get from their website:
https://antenna.uni-mb.si/trisat-api

cgbsat · September 7, 2020, 2:30pm

It’s pretty bad practice to reuse the NORAD and COSPAR IDs of a different, existing satellite!

fredy · September 7, 2020, 2:37pm

Good point!

I’ve changed the TLE above using the temporary NORAD ID we use in SatNOGS

1 99798U          20248.00000000  .00000000  00000-0  50000-3 0  9996
2 99798  97.5184 321.1086 0004082  14.9034 309.7984 15.09899686    05

thanks @s59mz, by the way do you know if they at least going to publish their decoding schema?

s59mz · September 7, 2020, 2:50pm

Yes, they say that will prepare a python script for parsing decoded data.

Currently, I can decode the records from SatNOGS with the new NASA-DNS/CCSDS decoder provided by @ea4gpz in his gr-satellites.

ea4bpn · September 7, 2020, 2:50pm

UPMSat-2 update (could no edit the message)

TLE seems correct from SatNOGS observations with object 2020-061E. AMSAT says 061F, which I think it is wrong from our own obervations. The dopler changes at high attitudes passes shows better close control with object 061E

Also an update for TLM decoding software:

V1.3 Date 07-09-2020
Fixed analog data table thanks to M.Rupprecht DK3WN and D. Estevez EA4GPZ

73, Rafael
EA4BPN

pierros · September 7, 2020, 3:56pm

Thanks for sharing those @ea4bpn ! If your team is interested you can create a custom dashboard in dashboard.satnogs.org that will be automatically updated with SatNOGS demodulated and decoded telemetry. Let us know or drop by #satnogs to help you with the process.

fredy · September 9, 2020, 2:30am

@mast @vedurk what is the time difference between CW and the FSK transmission?

I’m wondering if this reception could be TTU100:
https://network.satnogs.org/observations/2800588/

mast · September 9, 2020, 8:06am

With current settings, during normal operation the telemetry should be sent as

AX25 frame
delay 0.5s
AX25 frame
delay 0.5s
AX25 frame
delay 0.5s
morse transmission
delay 1 minute minus duration of morse transmission
delay 3 minutes
repeat sequence

s59mz · September 9, 2020, 10:38am

A very strange and strong FSK signal interfered with TRISAT downlink signal:
https://network.satnogs.org/observations/2805720/

It doesn’t look local and it was also decoded. Did anyone received it too?

vk5qi · September 9, 2020, 10:56am

Definitely a signal from another satellite from the doppler!
Maybe they should have coordinated their access to the 70cm band?

fredy · September 9, 2020, 11:11am

The other satellite is UWE-4, and they will have a couple of collisions over europe.

TLE of UWE-4 fit the signal.

s59mz · September 9, 2020, 11:39am

Thanks @fredy. The curve fits almost perfectly.

pierros · September 9, 2020, 12:07pm

@s59mz If you are in contact with the Trisat team can you please ask them about their violation of radio amateur band usage? What is their take?

s59mz · September 9, 2020, 6:59pm

I’m sure they are aware of what they are doing and I’m afraid I’m not the right person to talk to them about violating radio spectrum use. I’ve contacted them already as a ham just to ask them for a decoding schema.

The only thing I can do (and I’m willing to do), is helping to prepare a custom dashboard in dashboard.satnogs.org as a SatNOGS volunteer, when/if I get their decoding schema.

I’m interested in TRISAT because I’m from the same country as satellite is, and I’m not from their university team.

pierros · September 9, 2020, 8:05pm

@s59mz Thank your for the clariication, and thank you for pushing them to publish their endoding as they owe to.