Ed et al,
As I said in my posting the receive filter info came from a quote
attributed to Chen in the QST article. I pointed out that the link
supplied by QST was not for receive.
So we either have to accept the quote of Chen on the receive side
(additional data exists that Chen has?) or
Back in ye olde days of RTTY when we used mechanical printers, the
thinking was that the minimum bandwidth required was that sufficient to
pass the 3rd keying sideband without too much attenuation or time shift.
(This was way before measuring group delay was something that could be
done other
So we either have to accept the quote of Chen on the receive side
(additional data exists that Chen has?) or the QST author got it
wrong.
Chen has written extensively on RTTY filtering both on his web site
as well as in his postings on the RTTY list. In addition, Chen has
provided links to
This comes from June 2013 QST page 59.
According to W7AY:
The ideal RTTY filter is 280 Hz wide. Narrowing it further by 60 Hz
doubles the error rate.
The article references:
http://www.w7ay.net/site/Technical/RTTY%20Transmit%20Filters/index.html
Which doesn't come out and say the above!
Anyhow this may confirm what has been said on this reflector. The 350
Hz (AKA 250 Hz) filter is probably the narrowest practical choice for
RTTY.
This is a point that can not be emphasized too often. The 250 Hz
filter has a very rounded top that is being pushed hard to reach
Chen's 270 Hz
Brian K3KO wrote:
This comes from June 2013 QST page 59.
First of all, Chen's article is about transmit filtering which is not
directly translatable to optimal receive filtering. Second, the cascade
effect of the K3 crystal filter and DSP filter must be considered in
determining the net
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