09 Nov 2015, 18:51

Listening to satellites for 30 dollars

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I’ve ever dreamed of space & satellites, it turms out you can received pictures from them.
After getting my radio amateur license in the US, I’ve discovered there was some satellites dedicated to radio amateurs but also some weather satellites from the late 90s still working and capable of sending pictures from the space like this one NOOA-15.

SDR

You don’t need expensive hardware anymore thanks to the SDR movement Software defined radio and some great developers, a simple 20$ USB key and some pratices are good enough to make it work.

Software

There is plenty of softwares available but the ones I’m using for OSX or Linux are:

  • GQRX the software receiver
  • Audacity for sounds editing
  • Soundflower (OSX only) to reroute the sound from GQRX to Audacity, but you can do that with pulseaudio on Linux.

They are all free.

Know what, when and where to listen

The most important things to know is what frequency and when to listen to.
For that you need a software for passes prediction, I have developed an app for iOS devices called SatSat, it’s free (with ads), hoping enough people could be interested I’ll invest more into the product.

SatSat

Good satellites candidates for a start, some weather satellites, are:

  • NOAA-15
  • NOAA-18
  • NOAA-19

Experiment with GQRX options:
Receiver options -> Mode Narrow FM -> Mode options -> Max Dev APT 17k -> Tau OFF.
Record in mono inside Audacity at 11025Hz.

With the sound you just recorded, open it inside WXtoImg.

Cities are really noisy, expect best results outdoor, sometimes a simple wire antenna is enough for great results.

Here is an example of a weather satellite:
Sat view

And this is the “sound” of a satellite: