Mal
Fact. Everyone including G3KEV has missed my QRS3 and QRS10 on 500kHz
every time I have had it on, using this same TX, in fact I removed the
PIC which sends the QRS and inserted OPERA, viola PA0's at 493km decode me.
Please be technical not emotional about the subject it doesn't help.
73 Eddie
On 01/02/2012 09:10, mal hamilton wrote:
QRSS does NOT get lost or missed in the noise as you suggest and one can
always see at least part of the information trace, whereas Opera is all or
nothing and I have noticed at times a TRACE but NO DECODE.
I wonder what your next distortion of the facts will be
g3kev
----- Original Message -----
From: "qrss"<[email protected]>
To:<[email protected]>
Sent: Tuesday, January 31, 2012 11:37 PM
Subject: Re: LF: Re: Opera v qrs evaluation
Dear Jim, Rik, Laurence
Thanks for the information, it does seem from all tests that QRS3 and
OP4 are about equivalent.
QRS as we know takes a human to notice its there among noise and can get
missed. With OPERA (and WSPR) if there is an RX on in range it's de-coded.
73 Eddie G3ZJO
On 31/01/2012 22:51, James Moritz wrote:
Dear Eddie, LF Group,
I did a rough and ready comparative test on the "sensitivity" of QRSS3
and Op4 using your back-to-back transmissions. For 500kHz reception,
broadband noise from the broadcast stations just east of here is being
nulled out using a loop oriented N-S. Rotating the loop out of the
null position gives a convenient way of adjusting the SNR on Eddie's
signal. So I increased the noise level until I judged Eddie's QRSS was
just fully readable (using 0.3Hz FFT resolution), then left everything
in the same position for 4 transmissions, during which signal and
noise levels stayed nearly constant (see the attachment). Opera
reported an SNR of -31dB on Eddie's Op4 signal for all the
transmissions.
So, from what Graham said, Op4 may have a small margin in SNR with
these conditions. You could argue about what constitutes "readable"
QRSS, but there can't be more than a few dB difference between this
signal and something indecipherable without prior knowledge. It takes
4 minutes to send a callsign using Op4; you could increase the dot
length perhaps to 4s and transmit most callsigns in 4 minutes, which
would gain you about 1.2dB. But for practical purposes I think, in
this test anyway, the two modes are approximately equivalent in their
efficiency in sending callsigns.
Cheers, Jim Moritz
73 de M0BMU
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