@EU1SAT can you share IQ for this observation?
Maybe @PE0SAT is able to demodulate and confirm the signal is from SR0.
Here is a new TLE set generated for SR-0 by the latest Network observations:
SR-0 fredy 230 v1
1 98866U 24230.50465278 .00000000 00000-0 00000-0 0 08
2 98866 37.3946 293.9146 0005261 60.5903 321.9351 15.33534686 00
sr0_230_v1.dat (1.3 KB)
sites.txt (7.1 KB)
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9600 baud FSKAX25 (no G3RUH) should work if you have enough SNR
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Thanks for sharing your SR-0 recording, Vlad.
Tried my best both as an I/Q and FM demodulating it to audio, but even the best packet on the recording is just not enough to decode for me as 1k2 nor 9k6. Unless someone gets an above average capture one of these passes, the FSK being downlinked will be tough until they try the 1-watt TX power option at some point in the mission.
These SemTech chips work amazingly well transmitting LoRa, but the other modes that they can produce, like any transmitter of FSK, etc., just require more RF TX power to produce enough signal to be received cleanly.
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New TLE set from the latest observations:
SR-0
1 98866U 24231.38606481 .00000000 00000-0 00000-0 0 08
2 98866 37.3946 285.6487 0006417 51.4115 167.1602 15.33044910 09
sr0_231_v1.dat (1.3 KB)
sites.txt (7.1 KB)
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Thanks @EU1SAT!
So even if it looks pretty wide this confirms that the signal is 1k2. Also it confirms that despite of the space-track.org TLE sets, we follow the right object!
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Yes, I was following the location of tinyGS stations (including my own) decoding the LoRa beacons on several passes over the U.S. last night and the timing / position of ground stations hearing SR-0 match the most recent TLE calculated in this thread and are completely out of the published 2024-147* objects (so far)
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The Team in India behind SR-0 DemoSAT is just amazing…
While work continues to finalize both downlink & uplink documentation (as well as coding a conventional, stand-alone telemetry decoder), these guys have provided the steps to use ChatGPT (https://chatgpt.com/)
… to decode the downlink HEX bytes into human-readable telemetry values!
I can’t do this justice as it’s my first time on that site, so it’s easier just to try it and see for yourself.
After the free login, on the Message ChatGPT line at the bottom, you simply paste in the ENTIRE instruction below:
Decode the following byte array using the satellite_info structure. The data is in little-endian order. The structure is as follows:
struct satellite_info {
char call_sign[6];
uint16_t frame_number;
uint8_t message_type;
uint8_t transmission_power;
unsigned long satellite_unix_time;
int16_t obc_temperature;
int16_t battery_temperature;
int16_t external_temperature;
int16_t base_plate_temperature;
int16_t solar_panel_temperature;
int16_t radiation;
uint16_t bus_voltage;
int16_t bus_current;
uint16_t battery_maximum_capacity;
uint16_t battery_remaining_capacity;
uint16_t solar_bus_voltage;
uint16_t solar_bus_current;
uint16_t boot_counter;
uint8_t checksum;
};
The temperature readings are in Celsius, the current readings are in milliamps (mA), and the radiation readings are in µSv/h.
If transmission_power = 0, display as "100 mW"
If transmission_power = 1, display as "1 watt"
The values for obc_temperature, battery_temperature, external_temperature, base_plate_temperature, and solar_panel_temperature need to be divided by 10.
The values for solar_bus_voltage and bus_current need to be divided by 1000. The radiation value should be divided by 100. give only summary
… after that, you can paste in HEX decodes and watch the parsing of the data flow up the screen. A summary appears at the end.
The damn thing even tells you what it intends to do based on your instructions. And if you’d like to add to how it should behave (as I did to clarify the meaning of the ‘transmission_power’ byte), you can add that in separately.
The decode below was generated by pasting in one of last night’s decodes: (screen shot just shows the summary at the end)
53 52 30 53 41 54 FC 19 01 00 24 B4 C1 66 A4 00 E5 00 F6 FF 71 00 45 00 B8 01 23 10 DC FF 7A 0A 03 0C 2C 10 24 00 01 00 17
… so, I’m looking forward to updated documentation, especially the how-to for uplinking LoRa packets to SR-0’s ‘mailbox slot’ style store-and-forward message relay capability! In the meantime, I guess I can stop using my abacus and slide-rule to decode these telemetry packets thanks to the instructions that the Team has kindly provided for the ChatGPT site.
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SR-0 DemoSAT RAW Telemetry
Elv 4°, Range 2123 km, Sat Transmission Power 100 mW
1 Frame uploaded to @SatNOGS DB
https://db.satnogs.org/satellite/WZIT-9333-7102-4860-3049#data
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New TLE set:
SR-0
1 98866U 24232.38846065 .00000000 00000-0 00000-0 0 03
2 98866 37.3946 279.5144 0006232 56.0004 306.1246 15.33740273 08
sites.txt (7.1 KB)
sr0_232_v1.dat (1.3 KB)
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While there are updated TLE sets from space-track.org, none of them seems to fit or be close to our observations. So, we are going to keep producing TLE sets:
SR-0
1 98866U 24233.50000000 .00000000 00000-0 11284-2 0 07
2 98866 37.3798 273.0209 0008735 0.7089 29.6951 15.34147052 00
sr0_233_v1.dat (1.9 KB)
sites.txt (7.6 KB)
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Thanks very much for doing that!
Very odd… there is such a dense volume of tinyGS stations receiving the LoRa downlink that you can paint a somewhat accurate footprint of AOS over populated areas. And, as you say, those decodes do not track with any of the 2024-147x objects very well. (for now, anyway)
For what it’s worth, 147B does not plot in GPredict at all for some reason. So, unless that was a booster, etc., that has re-entered, perhaps there is an error in that object’s TLE.
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Indeed there is an issue with that TLE set, it looks like the rest has been fixed but not this. I’m expecting this to be SR-0 as this was the one fitted better on the initial (not very good) TLE sets from space-track.
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These are the latest TLE sets from space-track.org, with this update OBJECT B(60455) is fixed and in the right position to be SR-0, however it doesn’t fit the latest observations due to its old epoch.
Given that we don’t expect any other Object from this launch, we can identify SR-0, but I’ll wait a day or two to update it in DB in order to fully confirm it with a TLE for the Object with a more recent epoch. Until then I’ve set to follow it in SatNOGS DB for SR-0.
0 OBJECT A
1 60454U 24147A 24233.43401005 .00036090 00000-0 11284-2 0 9994
2 60454 37.3798 272.8617 0009501 359.3183 0.7563 15.32233640 301
0 OBJECT B
1 60455U 24147B 24231.54182212 .00036613 00000-0 10889-2 0 9992
2 60455 37.3826 284.5293 0013960 5.0400 355.0498 15.33763443 353
0 OBJECT C
1 60456U 24147C 24233.55674867 .00058587 00000-0 64511-3 0 9994
2 60456 36.9272 269.6593 0083797 287.4746 71.6869 15.57711301 686
0 OBJECT D
1 60457U 24147D 24233.55069617 .00027916 00000-0 74241-3 0 9999
2 60457 37.3670 271.9390 0029547 22.3440 337.8602 15.36964590 673
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One more generated TLE set:
SR-0
1 98866U 24236.40000000 .00000000 00000-0 10086-2 0 08
2 98866 37.3826 254.0883 0009565 25.0152 211.7825 15.34843187 08
sites.txt (8.0 KB)
sr0_236_v1.dat (2.6 KB)
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With the latest TLE sets from space-track.org we were able to identify SR-0 as OBJECT B (60455), here are the ikhnos results
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On these SR-0 passes over the U.S. for the past couple of nights, I noticed that tinyGS station N6RFM seemed to be decoding telemetry downlinks awfully early in the pass according to the most recent TLE for 2024-147B. So, tonight I took a closer look… here is the moment when Bob got the first decode of the most recent pass:
… while he has an amazing station and “Hears Everything”, that seems to be a bit of a stretch even for Bob. I plotted the most recent calculated TLE above (Thanks!!) and it’s nearly identical to the TLE for 2024-0147B. So, it appears that the TLE for 2024-147B might not be entirely accurate yet.
Guessing that Bob would get his first decode in the area of 10° elevation, the difference turned out to be 3.5 minutes. If anyone (like me!) is trying to AZ/EL track SR-0, you may wish to experiment with a time offset to see if you notice any difference - at least until the TLE is refined a bit more.
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