Friday, July 10, 2009

More Diversity

Things have been a little quiet on the SDR front and the bands have been lousy. Behind the scenes WIBR is being fine tuned in the "test" branch of the SVN, and diversity is moving ahead.

Above is the latest "polar" control for the diversity project. The control allows you to adjust phase and gain between 2 antennas and 2 receivers in the F5K. Here is a shot of the F5K with diversity active

This morning I was on early playing with the diversity feature. I used the controls to null the band noise. Below is a recording of a very weak CW station. As I click the diversity off and on, you can hear the band noise reduced in a way that takes the station from about a R-3 to R-5. I didn't have a lot of time to explore this as I was transcoding the file and loading it up to my server before I had to scoot, but I thought the demonstration dramatic enough to warrant a little display.

Noise Reduction

Sorry for the low audio you will probably need some cans to truly hear the difference. This station was at the noise about -119 on 40M. My diversity set up on 40 is a 65 ft end fed half wave antenna and a 45 ft vertical that is tuned remotely at its base. Both antennas are very close in output and seperated by about 180ft or 3/2 wave on 40. The signals are pretty independent since you can see very different AGC action on the panadapter of the 2 receivers.

Eventually tuning this feature will be automated. Its an interesting evolution to witness.