Oops, I meant to send it to the group !!!
----- Original Message -----
From: Steve Olney <[email protected]>
To: Stewart Nelson <[email protected]>
Sent: Sunday, January 28, 2001 7:57 AM
Subject: Re: [Lowfer] Proposed new LF signal format
G'day Stewart,
Great stuff !!! Once again the US LowFer mentality has produced some
quality work (don't work harder, work smarter).
Your knowledge and analysis are beyond my capability but it sounds good.
I
won't be able to evaluate it though as my spare time is totally committed
to
building up a FDK beacon (hardware and software) for evaluation.
I wonder, could you find time to do an evaluation of my FDK method
compared
to QRSS (0.4wpm, say) and your method. I know you are familiar with it,
but I will repeat the method here. Two tones are sent simultaneously
for
one minute to encode a single character. The operator (or the software)
need only pick out the two highest amplitude tones from a one minute
spectral analysis to receive the character. I have beta tested some
enhancing algorithms (I call smart-scan) which seem to work well, such a
centre frequency tracking to allow rejection of tone pairs which don't
have
a centre frequency close to the tracking centre frequency as well as
truncating the scan bandwidth around the centre tracking frequency. Also
a
run length integrator (but of course using mode, not mean) really lifts
the
performance.
Without all those algorithms, the bare FDK works down to -43dB S/N on my
tests (I don't know how accurate that is, you and Kyle could better
evaluate
it) while receiving a character/minute. I haven't evaluated it's
performance with the enhancing algorithms.
Good work !!! Keep it up !!!
P.S. I also think that long-term integration techniques with high
quality
frequency and time control will bridge the gap across the Atlantic (maybe
not first due to the vagaries of LF propagation) but certainly on a more
consistent basis. As you know I have been pushing the narrowband barrow
for some years now. Who knows maybe some day across the Pacific (must not
let ourselves be limited by reality).
73s Steve Olney (VK2ZTO/AXSO - QF56IK : Lat -33 34 07, Long +150 44 40)
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