A good test .WAV file is the Z2 file that is still I think the best LOWFER beacon aural DX, a mainland USA LOWFER beacon copied in Hawaii on a portable setup. I have a copy of the wave file here but
--Second bit of message having hit the send button by accident!!!! The Z2 wav file is quite a challenge aurally as well. I had to listen to it several times before I could pick out the callsign. 73 D
You will not be able to shrink files and make them audible without processing the .WAV file data considerably. Merely changing the sampling rate will do nothing to improve readability. The stages nec
1) Take the off air signal recording at (say) 8000 Hz sampling rate 2) Digitally mix down to some arbitrarily low frequency 3) Filter to the necessary sub-Hz bandwidth centred on the signal 4) Decim
If you plan to combine steps 3) and 4) by doing first decimating and then narrow band (sub-Hz) filtering, shouldn't you low pass filter the signal produced by the mixdown at 2) to have a bandwidth l
