Dear Erik,
Thankyou. I never got very far with HDSDR as my computer got overloaded and was not fast enough. I also never really got far with Softrock either, so what you managed to do is a bit confusing (to me), but you demonstrated that there is good separation at 10khz with a decent dynamic range between the two frequencies. A resolution bandwidth of 100hz on a professional SA will still only be able to separate two frequencies with 40 db dynamic range 1-2khz apart, because of the skirts of the rbw filters (or the virtual skirts implicit in the fft process).
The skirts were deliberately fairly wide (in the old analogue machines) to reduce ringing. Even so, using the narrowest rbw, you had to have such a slow sweep speed, that unless the display tube had a store function (how many people remember that), it was almost useless trying to follow the moving spot on the crt screen.
I think we all accept that there is a limit to what can be achieved and it is still an excellent device.
Steve L.?
