> Narrow IF filters are not desirable and reduce the
> performance of the demodulator , better simply use SSB filter
> GL ..73 -G..
Graham,
Why is that the case? What does the considerable extra bandwidth
achieve? Is the SSB bandwidth optimal, or would it be even better
with 10kHz bandwidth, or 100kHz?. Why is 3kHz better than perhaps
1kHz or 2kHz?
At first glance it appears crazy to let in all sorts of adjacent
channel QRM (the bandwidth is more than ten times the size of the
entire Opera window) when using a mode that occupies a fraction of
1Hz.
Is it simply that the 1.7kHz Tx tone is high enough for the SSB
filter to kill its harmonics, and on receive it is difficult to get a
1.7kHz tone out of a CW filter, even with passband shifting.
Am I missing something?
73 de Mike, G3XDV
g3xdv.blogspot.co.uk
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