>
>Bill said:
>
>> Ringing is part of the nature of band pass filtering.
>
>Not entirely so - if the bandpass filtering is Gaussian in transfer
>function, no
>ringing occurs on application of a step function. Generally, Gaussian filters
>aren't a lot of use for our 'narrow' point of view (SSB and CW), as they have
>insufficient selectivity. It is possible to produce a 'minimum ringing' CW
>filter by having a Gaussian 'top' down to about -12dB, and then going into a
>Chebycheff shape below that. According to Dave Leeson, W6NL (es W6QHS), a
>very
>badly mismatched CW bandwidth crystal filter can give you a Gaussian or near
>Gaussian response, albeit at the penalty of very high (20dB or more)
>insertion
>loss.
>
>Back before W2VJN took over International Radio, I asked them at Dayton about
>their CW filters and ringing. I was told that 'Our filters don't ring'.
>When I
>asked if they were Gaussian, he said 'No, but they don't ring'. Hmmmm......
>
? /chortle/
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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