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

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

TLE targeting for the new launch time at 2019-12-06T07:57:00Z based on @cgbsat initial TLE by using sattools.

1 84002U 14900A   19340.33125000  .00000000  00000-0  50000-4 0    01
2 84002  97.0040 197.0583 0002745   0.0000 200.0000 15.69144411    05
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The TLE above have been added into network… I’m going to remove some future observations based on the old TLE we had for this deployment and re-schedule the stations with the new ones, plus schedule other stations too.

Future observations with old TLE have been deleted… new observation will be scheduled after the launch in order to use the right TLE which probably are going to change due to delays of the launch.

New TLE for 2019-12-06T08:18:00Z:

1 84003U 14900A   19340.34583334  .00000000  00000-0  50000-4 0    01
2 84003  97.0040 202.3227 0002745   0.0000 200.0000 15.69144411    01

Observations have been scheduled for all 4 satellites in DB. I have shared almost equally the passes to the four of them for the next 6h. I will suggest not schedule after the first 6h (09:50-16:00) as new TLE may be announced that will be more accurate.

Thank You very much! Here, we are the developers of Smog-P and ATL-1 waiting for news…

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Are there any new TLE?

First passes we wait to observe signals:

Fossasat-1: https://network.satnogs.org/observations/1324797/
Smog-P: https://network.satnogs.org/observations/1324829/
ATL-1: https://network.satnogs.org/observations/1324867/
TRSI-Sat: https://network.satnogs.org/observations/1324839/

@tjanos @movax @ea4hcd1 Let us know if you get any initial TLE after the launch. Good luck on your missions!

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The latest are these in Electron Launch - RUNNING OUT OF FINGERS - 2019-11-28

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Thank you, we know this…

From the first passes:
Possible signal from Fossasat-1: https://network.satnogs.org/observations/1325454/
Possible signal from ATL-1: https://network.satnogs.org/observations/1324867/
Possible signal from Smog-P: https://network.satnogs.org/observations/1324839/
Nothing from TRSI-Sat yet.

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From other stations and from network stations until now only Smog-P and ATL-1 have been received:



We keep tracking their passes with SatNOGS Network by using the TLE we produced earlier. There are some initial TLE from space-track for this launch but we are almost sure that they are not the ones of the pocketqubes so we are not going to use them for now.

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