After five months of work, my new SDR recorder is up and running. I can now record and playback two synchronized I/Q radio channels for diversity reception.

Back in December 2022, I bemoaned the fact that no one has offered an SDR receiver that records dual channels at the same time. Such a feature would enable time-shifted beam-forming and noise cancellation. So, five months ago I decided to build one myself.  Above, you can see the original design concept, as well as a screen capture of the resulting software.

My code is more of a testbed proof-of-concept than a product. But after a lot of effort, I now have a working Software Defined Radio that will record one or two channels of baseband I/Q data And, it works well.

Here is a video demonstration of the software in action.

As of today, my project works with two receivers – Perseus single channel and RSPduo two-channel. Previously, I have described the architecture of this receiver. Over the next few weeks, I will describe how I manage the flow of data and the format used for my recordings.

Next, I plan to add my Afedri AFE-8222x dual channel receiver. Then, I will add my ability to do unattended scheduling of recordings.

My New SDR Recorder- Lots of Work

I built this software in a modular approach and it needs some fine tuning as I go along. More than 2 million lines of code are involved. Fortunately, a lot of this is third party libraries. My actual hand-written code is much smaller – around 10 thousand lines.

Modular code is much easier to debug, just a bunch of objects that connect and respond to each other in (hopefully) predictable ways.

Few things are as enjoyable as writing complicated software that actually works. Never the first time, of course. But each module gets improved until finally you have it.