At 03:14 PM 11/23/2004 -0000, Jim Moritz wrote:
[..]
The advantages of PSK31 are that there is readily available software, the
bandwidth is narrow enough, and people are familiar with it - but it isn't
particularly well suited to LF operation; it works fine when the band is
very quiet, but QRN impulses corrupt characters each time they occur, so the
band does not have to be very noisy to render the mode unusable except for
stations very close together. I think there is a case for a similar mode to
PSK31, but incorporating error correction, so that a moderate level of QRN
corrupting a small proportion of bits does not cause a big problem. VE2IQ's
"Coherent" mode did this quite well, but requires MS-DOS and dedicated
interface hardware, making it less attractive.
If you invoke the Coherent program with a "SB" command line parameter it
will use a sound card instead of the Sigma-Delta interface. It has been up
on my website since 2000; don't know if very many people tried it because
of the DOS thing. I do know some folks have tried in vain to get it working
with a sound card. A few minutes ago I brought up an old copy of COHERENT on
a new laptop computer and it worked first try with the built-in sound card.
You need a "BLASTER=" statement in the DOS environment to tell people which
base address, interrupt, DMA, etc to use for the sound card. That was
standard
stuff in the old DOS days if anyone still remembers it, hi! This software
works with *my* sound cards, namely those based on Soundblaster 16 or anything
built around an ESS688 or ESS1688 chip. Your mileage may (and probably will)
vary if you try other sound cards.
Bill
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