Observation 13966841: Drishti (98313)

Satellites & Observations Observations
1

Regarding Observation 13966841 …

Hi Freddy, will it be possible for you to send all the IQ samples that will be recorded for this satellite?

2

you should ask to the groundstation owner. @freddy only schedule it. btw not all gs record and save the iq file. the best solution is build your own ground station. click here for tutorial

3

Thank you for the reply, how do i contact the owner of the groundstation without using the discuss thread? Reason being that it can be flagged as spam and I need IQ samples from mulitple groundstation.

4

maybe you can start make obs from tu berlin gs
they provide iq file that you can download free here and here

5

Look at the meta data from an observation, there you can see if IQ storage is enable.

image

Then you can try and contact that ground-station owner via this community portal.

Jan | PE0SAT

1 Like
6

Thank you!

1 Like
7

The IQ from this example can be found at Index of /download/DRISHTI

9

Thank you!!

10

Thanks alot!!

11

super. but still not decoded

gr_satellites satyml:

name: DRISHTI
norad: 98313
data:
  &tlm Telemetry:
    telemetry: ax25
transmitters:
  9k6 GMSK AX100 downlink:
    frequency: 400.2000e+6
    modulation: FSK
    baudrate: 9600
    framing: AX100 ASM+Golay
    data:
    - *tlm
  9k6 GMSK G3RUH downlink:
    frequency: 400.2000e+6
    modulation: FSK
    baudrate: 9600
    framing: AX.25 G3RUH
    data:
    - *tlm
  9k6 GMSK NON G3RUH downlink:
    frequency: 400.2000e+6
    modulation: FSK
    baudrate: 9600
    deviation: 2400
    framing: AX.25
    data:
    - *tlm
  9k6 GMSK dev24 G3RUH downlink:
    frequency: 400.2000e+6
    modulation: FSK
    baudrate: 9600
    deviation: 2400
    framing: AX.25 G3RUH
    data:
    - *tlm
  9k6 FSK dev32 G3RUH downlink:
    frequency: 435.600e+6
    modulation: FSK
    baudrate: 9600
    deviation: 3200
    framing: AX.25 G3RUH
    data:
    - *tlm

hmmm.. inpired me to create “semi brute force” decoder using gr_satellites satyml… maybe someone already create it…

12

@PE0SAT , @bali and @epsilon Funny you should ask. lol With a lot opf help from Claude AI, and several hours of work, here is where I have landed this morning. It all seems plausible, but hard to be 100% certain. YMMV

Drishti_signal_analysis.pdf (227.2 KB)

Drishti.zip (6.0 KB)

Link to IQ file used (was called D2 but renamed with rx timestamp, etc.).

Good hunting all,

Bob

N6RFM

2 Likes
13

i should learn what prompt you use to generate that beautiful pdf analysis …

14

Simply create summary in pdf

15

@N6RFM

User suggested 9,375 baud

how you measure and estimate the baudrate?

16

Hmm, that baudrate reminds me of TRISAT.

This is the Yaml used with TRISAT, maybe they use CCSDS

name: TRISAT
norad: 46280
data:
  &tlm Telemetry:
    telemetry: trisat
transmitters:
  9766 baud FSK downlink:
    frequency: 435.6125e+6
    modulation: FSK
    baudrate: 9766
    framing: CCSDS Concatenated
    RS basis: dual
    convolutional: NASA-DSN
    frame size: 223
    data:
    - *tlm

Jan | PE0SAT

1 Like
17

Suggested by Claude to try various rates around 9k6.

18

iq file from obs 13967358

73!