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Date: Mon, 12 Sep 2005 10:49:03 -0400
To: rsgb_lf_group@blacksheep.org
From: Bill de Carle <ve2iq@magma.ca>
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At 02:52 PM 9/12/2005 +0100, Andy wrote:
>John -
[..]
>I'm surprised that you say the improvement with Africam was not that
>significant.   Surely, the biggest problem with any coherent scheme like PSK
>is maintaining symbol timing and carrier lock.  Certainly the timing can be
>determined exactly, on a continuous basis, and most of the coherency issue
>is resolvable too, so surely now that all the non-linear processing elements
>of PSK reception have gone away shouldn't the net gain be potentially
>massive ?

AFRICAM uses the GPS info for bit timing and framing, it does not attempt
to synthesize a coherent carrier.  I keep hearing how difficult it is to
get some of those DDS-based BPSK generators out there to switch coherently,
at least without some modification.  If anyone wants to transmit coherent
BPSK I'll look into the receive side this winter.

Bill