My Christmas wish list is dual channel baseband recording. A feature that would really bring DX to life for me. SDR developers, please!
As many of you know, I have spent the past few years experimenting with modern diversity reception. In particular, I use this feature for interference reduction and simple beamforming. It works great. Digitally, I can do magic with my RSPduo, ANAN and Afedri two-channel receivers. Plus, I can use an NCC-1 to perform similar feats on my Perseus and Flex single channel radios.
On great feature of the RSPduo and Perseus gear is my ability to schedule baseband recordings. So, for example, I can set SDR Console to record all of the Medium Wave broadcast band for ten minutes at 4 o’clock in the morning. And play it back later, when I am awake. This is great for MW DX.
My issue is that the software – SDRuno or SDR Console – will only record one channel of baseband I/Q data. In order to do diversity reception on playback, what I really need is dual channel baseband recording. Which, sadly, no one provides.
So, this is frustrating. As you can see above, I have radios which receive two coherent channels, above left. And, I have software which processes two channels synchronously to enable modern diversity reception, above right. But the capability to save and play back a chunk of radio data in two channel format is missing.
Would this feature be hard to implement? Not really. If we can receive and process two channels coherently, saving it as a multi-channel WAV file should be straightforward. Yes, you would need time stamps and/or block numbers for synchronization, but this is not rocket science.
Dual Channel Baseband Recording – Use Case
My simplest use case for this feature would be Medium Wave DX. You could record chunks of AM BCB at night and do your beamforming for different stations during the day. I think this would work remarkably well with a wideband loop array.
Another use would be fine tuning interference cancellation anywhere your SDR tuned, just as you do during live reception.
So, hopefully software developers for PowerSDR, SDRconnect and SDR Console will consider adding this feature. I know it’s been around for years in the signals intelligence world.