New Satellites: Plan for SSO-A SmallSat Express Launch on November 19

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#21

Hey,

I already started integrating support for PW-Sat2 some days ago. It is not yet in the satnogs-decoders repo as there are some questions left over. Let me get back to you later today as I am far away from a PC atm.

You can find the ‘decoder-struct’ I am working on in my personal repo, here:

The BPSK decoder currently used in gr-satnogs was originally developed for PICSAT, but it is not tested very well as PICSAT just died as it was ready :confused:


#22

As I can see there are lots of correctly decoded PicSat frames so the BPSK decoder did the job. I’ve got IQ recording from PW-Sat2 transceiver (recorded by FUNcube pro+) that I’m eager to share for testing purposes. Actually, we’ve published a few short IQ recordings at all symbol rates supported by our transceiver but they do not contain telemetry (beacon) frames. So just let me know if you need some more recordings!

@DL4PD - I’ve cross-checked your parser with our python-based and unfortunately there is an issue with Kaitai - https://github.com/kaitai-io/kaitai_struct/issues/155 It’s not possible for now in version 0.8 to have LE when reading bits (even though you’ve specified LE). I’m looking for solution but I’m new to kaitai. Is that the only option for SatNOGS telemetry parser? Maybe it’s better to use/adapt already prepared parser https://github.com/PW-Sat2/FramePayloadDecoder? It has also raw values to SI units conversion. Maybe we can wrap it as GRC block?


#23

I’ve suggested BPSK1k2 and BPSK9k6 transmitters for PW-Sat2 in the database but I’m confused, should I add another possible symbol rates 2k4 and 4k8? The basic and default transmission symbol rate is 1k2, but if we have sufficient SNR we’ll switch (via telecommand) to some higher baud rate (not necessary, but preferably BPSK9k6).

PS. If you would like to add a picture of PW-Sat2 to your database - check out our Flickr.


#24

Hi @begreen thanks for all these info!

I have added your suggested transmitters, please feel free to add the other rates as new transmitters as well. And have in mind to let us know of any changes in the rate while PW-Sat2 will be in space, in order to schedule observations with the right transmitters.

I’ve also added a picture of the satellite. :slight_smile:

About the IQs I guess they will help… we let you know if we need something more :slight_smile:


#25

Thanks a lot, @fredy!

As I can see, there is an “generic” option BPSK and BPSK1k2 and BPSK9k6 but BPSK2k4 and BPSK4k8 are missing. :frowning: Should I choose just BPSK or there is something that I can do to make other baud rates available?

image

Sure, we’ll inform about our activities. Our current plan is to post the info about current/planned changes via our Twitter account but if you can propose better option to inform SatNOGS community I’m open for it. :slight_smile:


#26

9k6 is only roughly tested. IIRC it is “on the edge” of the decodeable symbolrate with the current flowgraph (which could be edited). Some IQ files would be great :slight_smile:

The LE problem is already known and you can see what could be done as a workaround in the fox.ksy.
Unfortunately there is an issue with the dict translation in the database, so kaitai instance values don’t show up as result in the json object tree.

Working on it :slight_smile:


#27

I think you can choose BPSK as generic script and specify the baudrate in the parameter.


#28

I was also trying with instance approach, but the whole parser will look like as horrible workaround. :frowning: Additional question is if there is an option to add units converter? PW-Sat2 sends all values as raw, so it’s not human-readable…

PS. Maybe we can create separate thread for PW-Sat2 telemetry decoder to not ‘spam’ general SSO-A thread?


#29

BPSK with the right baudrate would be ok, however I’ve just added the missing ones so you can go better with them, thanks for pointing this out. Mode name is shown when you choose transmitter for an observation, so it will make it easier to have the baudrate into mode name. :slight_smile:

Twitter is ok for updates, just to make sure that we will see it asap add into your tweet @satnogs mention of our twitter account. An alternative would be a specific topic here for PW-Sat2 and posting any updates.


#30

At the moment I am trying to avoid converting raw values inside the .ksy file but instead convert them in the grafana dashbaord.
It is not very nice looking with the LE conversion I did in fox.ksy and I thought of a custom process in kaitai, but we also try to avoid using custom processes. Since this would be a re-usable process, it might be worth the efforts.

Let’s start a new thread for PW-Sat2 as there might be some more challenges :wink:


PW-Sat2 Telemetry decoder
#31

Looks like it’s the 28th!


#32

A last try just in case you have not seen the question.

Do you think you could share the GMAT script to begin learning
this wonderful tool? The one you used to compute the TLE.

I have installed GMAT recently but scripts are still a bit obscure for me
for the moment. I would need some samples in selected cases.
Yours would be just fine.

73,


#33

Apologies. I’d seen your post but hadn’t gotten around to recreate the script.

This is how to setup the ECEF state vector in GMAT. You can then propagate the script and change things as you see fit.

Here’s the script (you may have to rename it to eseo.script for GMAT to see it).
eseo.csv (6.0 KB)


#34

Thank you for your time :slight_smile:


#35

This is a TLE based on the ECEF state vector but for the December 2, 18:31:47 launch time:

1 71002U 18835A   18336.78165509  .00000000  00000-0  50000-4 0    09
2 71002  97.8283  45.1177 0015055 286.2236 242.6240 14.96918974    07

#36

43 Transmitters for 22 Satellites in DB

Tomorrow I’ll add the TLEs in order to be able to schedule them.

We will try to share all the stations between those satellites, please if you have a preference for your station contact me or remove any scheduled observation to schedule the one you want.

Please try to avoid scheduling 1 satellite in all stations. For the number of the station and the number of the satellites if we want to share it as fair as possible we should schedule ~2-3 passes per satellite per day.

Please also try to choose transmitter that are described as TLM (telemetry) or Beacon.

If you have any question/comment feel free to post here or send a pm.

Thank you!

Some stats about the transmitters:
14 VHF
24 UHF
5 S-Band


#37

Launch bumped a day: https://twitter.com/SpaceX/status/1069133406586363904


#38

Hello! My name is Tolkynay (Tori) for short. I am from Kazakhstan, our nanosatellite “al-Farabi-2” is going to be launched today with Falcon 9. Thank you to Libre Space Foundation about sharing information. We would like to ask radio amateurs from all over the world to catch the signal from our al-Farabi-2! Below we wil be giving some information. I am not fully recognized with what kind of information should be provided here, but always in the line if some clarifications are needed.
The satellite was developed and assembled by al-Farabi Kazakh National University students with the purpose to conduct scientific experiments in space.

The satellite will transmit the CW signals with the “AF-2” message every 3 minutes.
Satellite data:

Callsign: UN1GWA
Frequency: 436,5 MHz
Modulation: CW.
Output power: 1 W.
Antenna: non-directional
Telemetry frequency: 436,5 MHz
Telemetry modulation: GMSK-4800
Initial orbital data:
UTC time at liftoff: 323:18:31:47.990
UTC time of current state: 323:19:14:59.490
Mission elapsed time (s): +2591.50
ECEF (X,Y,Z) Position (m): +299136.050, +1606142.483, -6757861.349
ECEF (X,Y,Z) Velocity* (m/s): +5500.939, +5093.215, +1454.386
LVLH to BODY quaternion (S,X,Y,Z): +0.0064870, -0.9999740, -0.0007769, -0.0030674
Inertial body rates (X,Y,Z) (deg/s): +0.1688750, +0.0721098, -0.0220705
Apogee Altitude** (km): +574.414
Perigee Altitude** (km): +558.083
Inclination (deg): +97.775
Argument of Perigee (deg): +98.797
Longitude of the Asc. Node*** (deg): +45.066
True Anomaly (deg): +182.386

  • ECEF velocity is Earth relative
    ** Apogee/Perigee altitude assumes a spherical Earth, 6378.137 km radius
    *** LAN is defined as the angle between Greenwich Meridian (Earth longitude 0)
    and the ascending node
    **** All orbital elements are defined as osculating at the instant of the printed state. Orbital elements are computed in an inertial frame realized by inertially freezing the WGS84 ECEF frame at time of current state.
    And of course, we have some gifts for that:
    First 10 radioamateurs which will receive the satellite signals and will send the confirmation of their reception at the email address stated below will receive memorial plaque. Email: ntpkaznu@gmail.com

Email subject must contain the following text: al-farabi-2. It’s advised that email should only contain the link to the video made and posted on the YouTube or similar video hosting.

Email must contain the name and surname of the radio amateur, his/her callsign (if available), reception time/date, QTH-locator of the station used to receive the signals as well as brief information about the receiver and antenna used. All radio amateurs who will send their signal reception confirmation will receive memorial diplomas issued in the electronic format.


#39

Here’s an orbital estimate for the December 3 launch. This uses the December 2 TLE (71002) which was determined from the December 2 state vector.

1 71003U 18337A   18337.78165509  .00000000  00000-0  50000-4 0    08
2 71003  97.8283  46.1033 0015055 286.2236 242.6240 14.96918974    00

#40

@Tori_alfarabi2 welcome!

For this launch in skyrocket.de site, I can see only two satellites from Kazakhsatn:
https://space.skyrocket.de/doc_sdat/kazstsat.htm and https://space.skyrocket.de/doc_sdat/kazscisat-1.htm

There is an entry for al-Farabi-2 , https://space.skyrocket.de/doc_sdat/al-farabi-2.htm but it doesn’t give any details about its deployment. Is the case that one of the above has been replaced with al-Farabi-2?

I’m going to add it into our db, I let you know when is done.

Thank you!