Peter
Perhaps another mode worth trying is WSQ by ZL1BPU:
http://www.qsl.net/zl1bpu/SOFT/WSQ.htm
It is intended for LF/MF, so doppler effects on higher frequencies may
present issues. I've tested this mode on 630m with copy still good down
to -24 to -25 dB.
73 Eric NO3M
On 04/23/2014 10:10 AM, Peter R. Burri wrote:
Hi Edson
Thanks for your answer. Yes I have already considered and even tested
other digimodes (I am into digimodes for years and do nearly nothing
else in ham radio, hi hi). I agree with you in that Olivia is by far
the strongest and most reliable **ragchew mode** available today
working with relatively weak signals. Therefore Olivia is my favourite
digimode for most applications. Nevertheless when it comes to
**really** weak signals, longest distances or low power equipnent/low
performance antennas it lies behind JT65 by magnitudes. I have tested
both modes with just a few minutes difference in time last week
between HB and ZL and JT65 worked with 100% decoding while Oliva
decoded only a fragment of text from time to time resulting in
unreadable information. The station in ZL (a colleague of mine)
engaged a simple 5 meter wire (14 MHz) held up by a fishing rod and a
KX3 running on internal batteries outdoors near Auckland. We used the
protocol mentioned for message transmission (every fragment confirmed
by an RRR with repetition if the RRR could not be received back).
Perfect copy down to 100 mW of power with just a few repetitions. I
guess we won't be able find another mode (except QRSS which is
somewhat uncomfortable) performing this way down to S/N of -23 dB or
less. So (at least to me) it seems worth some effort to realize
something like an "SMS-Sender" for hams with an underlying JT65
transport layer even if the transmission of such an "SMS" takes half
an hour (I can lean back and eat a donut while transmission is in
progress J)... And going there (to ZL) would take a lot more of time
and money J.
73, Peter
HB9JAQ
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