Electron Launch - RUNNING OUT OF FINGERS - 2019-11-28

The next upcoming launch with amateur satellites is the Electron Launch that has FossaSat-1 on it. :smiley:

The following is a list of satellites and there IARU entries.

SMOG-P - https://space.skyrocket.de/doc_sdat/smog-p.htm - http://www.amsatuk.me.uk/iaru/finished_detail.php?serialnum=641
TRSI-Sat - https://space.skyrocket.de/doc_sdat/trsi-sat.htm - http://www.amsatuk.me.uk/iaru/finished_detail.php?serialnum=649
ATL 1 - https://space.skyrocket.de/doc_sdat/atl-1.htm -http://www.amsatuk.me.uk/iaru/finished_detail.php?serialnum=640

And finally

FossaSat-1 - https://space.skyrocket.de/doc_sdat/fossasat-1.htm - http://www.amsatuk.me.uk/iaru/finished_detail.php?serialnum=652

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So for FossaSat-1, what demodulator is going to be best to capture the signals transmitted?
Clearly the 125 kHz LoRa signal is too wide to be captured within the passband of any of the current demod flowgraphs, so we won’t even be able to capture wide enough IQ for analysis. Maybe we need a ‘generic waterfall + IQ only’ flowgraph for situations like these?

As for the RTTY signal, that really needs a single-sideband demodulator. The CW demod flowgraph is the only one of these we have at the moment. As an interim step, maybe set this sats transmitter to CW, so there’s a chance of getting some audio that can be demodulated in something like fldigi? The 3 kHz passband is going to mean it might take a few tries to get the signal lined up right, depending on drift, etc…

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Satellites have been added in DB… I’m going to add the transmitters tomorrow, feel free to add suggestion until then. :slight_smile:

Also we will need some initial TLEs, if anyone finds or calculates ones let me know.

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Hey guys, FossaSat-1 builder here :slight_smile: As you know first 24 hours are critical for knowing if the mission is succesful (even if we can’t decode stuff we can know if the antennas and solar panels deployed from the signals) so any detecting is really really useful, especially fist hours where we have no coverage.

This is the information that I have:

State Vector at Deployment (including jettison delta-V):
Position ECEF [km]: [-979.7370, 1251.2910, -6547.6418]
Velocity ECEF [km/s]: [7.1674, -2.5155, -1.5525]
Nom. Inclination = 97.004
Nom.Apogee Alt: 363.2
Nom.Perigee alt: 359.5
Nom.RAAN: -171,874

Deployment at 6405s from clamp release. We turn on 5m after deployment.

Will update in the morning but our predictions give early passes at Perth. Thanks!

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As clarification of the above, ‘clamp release’ essentially means launch time. Currently scheduled for 07:56:22Z, but may be delayed (which means the TLE will need to be recomputed).

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Here’s a TLE based on the information by @ea4hcd1.

1 84001U          19333.33081019  .00000000  00000-0  50000-4 0    09
2 84001  97.0040 190.0000 0002745   0.0000 200.0000 15.69144411    01
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TLE targeting for the new launch time at 2019-11-29T08:20:00Z based on @cgbsat initial TLE by using sattools.

1 84002U          19333.34722223  .00000000  00000-0  50000-4 0    00
2 84002  97.0040 195.9245 0002745   0.0000 200.0000 15.69144411    07
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Transmitters are now in DB and the first observations are scheduled.

Two notes:

  1. For Fossasat’s RTTY we selected BPSK1k2 mode as it may let us decode it as for this mode stations use bpsk gr-script instead of the generic FM one
  2. We have scheduled for the first 5 hours, given that the launch will be at 2019-11-29T08:20:00Z, if you want to schedule for later please don’t go to far in the future as the TLE may change before or after launch.
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Hey Everyone, first pass on a SATNOGS station will be aprox from 11:24:25 until 11:30:49 on South Australia Stations (Not sure which one is the . Then we will get a pass over the 453 - IFSC-SJ station from 11:54:29 until 12:01:10. Is it possible to program observation on these stations?

I will keep you guys updated. On everything, maybe someone can do some pass predictions using the TLE’s

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Scrubbed for today, will update asap on launch date.

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Hey Julian!
I would like to invite you to join our chatroom prior to the next launch approach. It would be a lot faster to get answers in there :wink:

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Hey Everyone,

it´s Paul, the builder of TRSI-Sat.

Our MFSK modulation scheme is nonstandard due to the radio chip we used.
Can the SatNogs MFSK demodulation deal with 156.25 Hz frequency steps?

If not, I would suggest to use upper sideband instead (zero-frq starting like 2kHz lower: 437.073), so the data could be preserved in the audio.
Alternatively CW that preserves the band around 437.075 as audio.

The bandwidth is 3kHz, but - if possible - a wider bandwidth would be better in case we are a bit off.

Cheers, Paul

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156.25 Hz sounds familiar… SiLabs chip?

Agreed, I think a better approach is to do the same as being used for Fossasat-1, which is to use the BPSK Demodulation flow-graph, which will save USB-demodulated audio (and completely fail to demodulate any BPSK, but thats OK). The BPSK demodulator automatically aims for the signal to be at a 1.5 kHz IF in the demodulated audio, so there should be no need to adjust the RX frequency from the nominal.
The CW decoder does the same, but it will likely mistakenly decode some CW data, which will cause the observation to be incorrectly flagged as valid (known issue).

I’m pretty sure the RX will be off-frequency initially, due to TLE inaccuracies and other drift. A few stations (mine included) are set up to save IQ data, so that will help.

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Awesome! Thanx a lot!
PS: SI4432 - Chip :smiley:

Old-school SiLab chip… Hopefully the reference is something stable-ish?

Any more details on the modulation? I’m wondering if I can throw together a demodulator using David Rowe’s fsk_demod utility. We use a 4FSK downlink on our high-altitude balloon flights, also modulated using a Si4432 (on a recovered an reprogrammed Vaisala RS41 radiosonde) - some info on this here.

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Yes, on my site I put details about demodulation:
www.uac-lab.com, under the tab “TRSI Sat info”.
You can find I/Q-WAVs there, recorded under different RX conditions.

Some other thing:
A year ago or so I wrote a baseband codec which LOSSLESSLY compresses the huge recorded I/Q-WAV into a 40kHz baseband I/Q with only 20kbyte/sec - with the hope it would be integrated into SatNogs. It´s really the raw data, preserving all phase information losslessly stored.
I have put the encoder/decoder into GitHub, it´s plain C code, has been compiled on Raspi by a comunity member (long ago, I already forgot who took care of porting it, must be in the logs somewhere), but I unfortunately didn´t have time to take care of it anymore. It looks that this codec is just rotting away. It´s a pity, because raw data is extremely valuable when there is no demodulator around. It could be demodulated even years later, and the specific observation would not be lost. This could be a valuable tool, as it really doesn´t create big files, and the decoder creates a standard I/Q-WAV from the compressed file.
(It makes I/Q frequency shifting, sharp low pass filtering with practically no overshoots, Huffman encoding of sample differences and creates/restores an I/Q wave with a selected bandwidth and frequency shift. No zero-frq errors, fast processing, generates standard WAVs, readable with HDSDR or SDR#, command line examples included. It´s only for 8bit waves, time was too low to include a 16bit version, but WAVs could be downconverted before compressing)

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Now planned for Friday at same time, will update tomorrow of weather which is the last point to sort out.

Thanks!

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Hey, Still planned for tomorrow at same time. will update as we go forward.

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@vk5qi @movax

I’ve added the bpsk transmitter for TRSI-Sat as you suggested in DB. Feel free to suggest any changes if needed here or directly in DB.

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RocketLab tweet:


Today’s launch window is open from 07:57 - 09:22 UTC (20:57 - 22:22 NZDT). http://www.rocketlabusa.com/live-stream