Monday, May 4, 2009

Phase 2

Here is a shot of PowerSDR with Bob's DSP test form open. I decided to run some tests on this thing. I have a pair of 80 and 40M verticals that are spaced about 100ft. I fed one vertical into ANT-1 on the F5K, and I fed the other into RX-2. I turned on the DSP Test Form, as shown above.

First I tuned to a broadcast station that is about 4 miles north of me. The signal on my pair of 80/40M verticals were -20 dBm on one vertical and -23 dBm on the other. (aka about 50 over S-9.) In other words its one friggin strong signal. By judicious tuning I was able to completely null this strong signal. This signal is about 30dB stronger than the strongest of signals I ever encounter on the air. Next I tuned to 40M to hear what I could hear. These are a few samples I recorded of QSO's and noise being nulled.

40-A 40-B 40-C 40-D

In A you can hear the noise reduction. I tuned to best signal quality and then just clicked enable off and on a few times. This means my noise is a point source comming from a specific location.

In B In this clip you can hear the station fade down into the noise and when I click on the noise canceling he become readable again. The effect was more pronounced at different times during the QSO, but if I record a long QSO the files become huge.

In C is a classic situation. This "maddening" kind of digital noise is completely eliminated from the background.

In D another noise is eliminated virtually completely in a very noisy band

As you can see on the console I have no other noise abatement turned on for this demonstration.

I did run across 2 QSO's on the same freq, and I was able to eliminate one of the QSO's while copying the other using this diversity technique, and then do the opposite, eliminate the other QSO and listen to the QSO I had just notched. Amazing!!! I didn't make a clip of that because the QSO ended just as I got the hang of the tuning and was moving toward the "rec" button.

I am very excited about this development