From: "Bruce Lifter, WT4I rr" <wt4i@cfl.rr.com>
To: <rtty@contesting.com>
Date: Tue, 28 Aug 2001 19:09:17 -0400
It is my experience that both 250Hz and 500Hz filters both have their
strengths.
I generally run with 500 Hz filters unless the bands get too crowded.
I like to hear what is close to me. Additionally, I like my TNCs to copy
wide. If I get called off frequency, I do not want to play with the RIT.
Some of my TNCs will actually copy stations as much as 40-50 Hz off
frequency.
<text deleted>
Also consider that it is theoretically possible to copy RTTY with just
one of the tones.
73, Bruce
Bruce has touched on a couple of things here. Theoretically, a FSK
signal is only slightly wider than a OOK (CW) signal at the same
speed; and that's wider than 250Hz at 100WPM, but just how much of
that is necessary for good copy? And that depends on the HF modem.
So, there is no simple answer; the filtering and decoding is all part
of one system.
73, doug
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