On Wed, 9 Jun 2010 18:37:33 -0500, "Robert Chudek - K0RC"
>No one will be using a wider shift. It wastes bandwidth and is prone to more
It's true that wider shift does use more bandwidth, but in fact,
errors are actually reduced, provided you have a receiver and software
which can take advantage of it. Wider shift reduces the deleterious
effects of selective fading.
Narrow shift causes the mark and space to selectively fade together,
where a wider shift causes them to selectively fade differently. If
the RX bandwidth is wide enough to accommodate both and the software
is capable of correctly decoding when only one tone is present,
reception is actually improved.
The 170 Hz shift used by hams is a compromise between selective fading
and crowded bands. Commercial and military stations who care little
about crowded bands commonly use a much wider shift, for good reason.
73, Bill W6WRT
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