If close in signals are not a worry then certainly a digital filter is indicated. The one large advantage of a digital filter is that there is no phase distortion. Thus ringing is minimum. But you need a very good 24 bit codec.
On Tue 13 Aug, 2019, 12:30 PM Tom, wb6b, <wb6b@...> wrote:
Hi,
Are there any comparisons that would indicate if a narrower bandwidth crystal filter verses an audio bandpass filter perform better? In some ways the audio filter is just another filter in the IF chain, and the current crystal filter becomes a second roofing filter.
Also, it would seem with DSP technology, filters, noise reduction and such would be possible in ways that were never possible with tried and true crystal filters and analog techniques. Have DSP audio processors delivered on these possibilities?
My old school HF transceiver has a narrow CW crystal filter and it seems to work well, but for my UBitx maybe something new school would be more practical.
In a field day situation if a high power station was near by in distance and frequency it could help. But if the radio was good enough to not overload, in that case, is it due to the crystal filter or simply the design of the receiver can handle a high dynamic range?
Are there any good articles or comparisons of one over the other? I'd been thinking of adding a audio bandpass filter to my UBitx, but sounds like it is not difficult to add a narrower crystal filter if done in "parallel" as suggested here. The difference in IF frequency seems like it would just be a software change, unlike radios of old.?
