Eric
I found that even the author of this article says: "Don't even think about
using the software on HF. There is far too much Doppler shift (except on
ground wave) for the receiver to work reliably. Even 160m will be a
challenge at night."
So maybe still better go with JT modes ? ;-) Thanks anyway for the hint.
73, Peter
HB9JAQ
From: Eric NO3M [mailto:n...@no3m.net]
Sent: Mittwoch, 23. April 2014 19:22
To: wsjt-devel@lists.sourceforge.net
Subject: Re: [wsjt-devel] Remote Control
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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