SDR’s killer app?

Andres Vahter, whom I discovered through’s blog, has created command line apps to do Doppler corrections based on a Ham satellite’s red shift (wavelength stretch) and blue shift (wavelength compression) IN REAL TIME using satellite data (current Keplerian elements).

The idea that an SDR coupled with the right right software tools can automatically tune to a satellite’s downlink frequency even as it compresses or stretches its radio transmission as it approaches us and then recedes is just the most empowering application I’ve ever heard or conceived of for SDR — beyond the simple fact that SDR is an amazing mathematical reality.  Wow.  Thank you Andres for strengthening our tool set!

I am new to the field because of my concerns with Software Defined Radio (SDR) and, let’s be honest, time and energy constraints, so forgive me if de-Dopplering as signal is an old SDR topic.  It’s new to me and maybe some of you as well.  Either way, since I find comfort on the Linux/BSD/Unix command line, this implementation is right up my alley.

Here are links directly to Andres’ blog:

Further reading on Ham satellites