Contents


Work in progress.

Notes

  • Keep in mind that the output is upside down if the satellite went from south to north instead of north to south that day.

  • Audio sample on SigidWiki

  • These satellites send images at realtime, line by line. Something like a 1000x1 resolution video or like a flying scanner. These satellites fly on a polar orbit (north to south and south to north).

  • You don’t need a LNA or a high antenna. I’m using a Double Cross Antenna, roughly 2m above the ground and 3-4m of RG-58 coax. Probably helps being far from big cities.

  • For satellite tracking I use gpredict. Otherwise I use the Heavens-Above Android App/Website.

  • For NOAA, first I record a WAV file on GQRX using the following settings. I don’t know if these are the best settings, but it should work.

    • Demodulation: WFM (mono).

    • Filter Width: Custom, just wide enough so the signal fits as you can see on the spectrum analyzer.

    • Filter Shape: Normal.

    • AGC: off.

    • Noise Blanker: No.

    • Squelch: Disabled (-150dB).

    • LNA gain: Max, but you can play with it and guess where it has the best signal to noise ratio.

    • I don’t use any of “DC remove”, “I/Q Balance”, etc.

    • Input rate: 1800000

    • Decimation: None.

Frequencies

  • NOAA 15: 137.62MHz.

  • NOAA 18: 137.9125MHz.

  • NOAA 19: 137.1MHz.