The following 100 Hz DSP CW filter response was measured
with a calibrated signal fed directly to ADC input on A7 board.
156 Hz width at -6 dB
378 Hz width at -40 dB (sidelobe peak)
512 Hz width at -49 dB (sidelobe peak)
660 Hz width at -56 dB (sidelobe peak)
796 Hz width at -62 dB (sidelobe peak)
463 Hz width at -67 dB (sidelobe peak)
1072 Hz width at -70 dB (sidelobe peak)
1210 Hz width at -75 dB (sidelobe peak)
Both S meter and AGC respond happily to sidelobes as measured.
The response is essentially the same as with V1 firmware.
V2 apparently introduces an additional audio filter preventing
sidelobes from being heard, which may be useful in some circumstances,
although many would not call it "real" selectivity as the AGC is
still being keyed by strong signals more than half a kHz away.
Selectivity measurements by spectral analysis of the audio response
to white noise will show combined selectivity of IF and audio filters.
I wouldn't consider this a bug.
It is an "unpublished feature", although somewhat misleading one.
73,
Sinisa YT1NT, VE3EA
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