New software: SatNOGS waterfall tabulation helper

orbits
strf
tle

#1

Hi,

[Add introduction to SatNOGS TLE sources, need of doppler measurements, current proposals/plans for timestamped waterfalls here] :laughing:

here I present the waterfall_tabulation_helper.py, a new script to extract rough doppler measurements from SatNOGS waterfall png files. It’s based on my script to extract doppler measurements for Change-4, adjusted to read SatNOGS waterfall pngs and extended to remove the doppler correction performed by the satnogs-client during the observation. It’s purpose is similar to rfplot in STRF. Upon invocation it downloads the waterfall png and obervation metadata and allows the user to extract measurements. Those measurements are then stored in a STRF-compatible file.

Please let me know if you have feedback / ideas!

Best wishes,
Fabian

Example usage

LightSail-2 in observation 806927.

  • Start the helper script with
    satnogs_waterfall_tabulation_helper.py 806927
    
  • Follow the procedures at Data tabulation method

The waterfall including the manually placed markers will look similar to the following:


The extracted markers are saved in an STRF-compatible file (806927.dat).
With rffit the doppler measurements can be compared to TLEs:

These are space-track TLEs (with an epoch near the observation time).

Notes:

  • Frequency-drifted transmitters might not be handled properly at the moment.
  • The script requires a waterfall png from the latest satnogs-client with a bandwidth of 48 kHz. Some observations seem to have waterfalls with different bandwidths.

Falcon Heavy Launch 2019-06-25 03:30 UTC
#2

Nice work!

Instead of using a site code we should write out the coordinates in the output file. I can adapt rffit from STRF to read those and perform the analysis.