Re: LF: QRSS3 "challenge" results

[Roger Lapthorn <rogerlapthorn@gmail.com>]

Rik's comment that WSPR is roughly equivalent to QRSS10 is interesting and ties up well with my own experience: with QRPp and a small antenna QRSS3 was a struggle (100km) , QRSS30 got me a decent distance (300km +) and WSPR got me somewhere in the middle (250km) .

It still surprises me that more people don't use WSPR on 136kHz for beaconing when it is stable, reliable, very well documented and has all the advantages of an internet database to almost instantly check how well your signal is being propagated. I guess the disadvantages are the need for a linear PA and the timing accuracy. I've still not re-installed OPERA as I know it would be a CPU struggle with my PC.

73s
Roger G3XBM

On 8 February 2012 18:32, James Moritz <james.moritz@btopenworld.com> wrote:

Dear Andy, Rik, LF Group,

G4JNT wrote:
...>When you generasted the Opera and WSPR audio files, did you take into
account that Opera should be compared using the mean power?  With its
50% duty cycle, this means an Opera Tx has to have twice the power

rating of one running WSPR for equal S/N ratios...>

... But on the other hand, you could argue that since the TX power is in practice normally limited by the PEP available from the PA. So by having 100% duty cycle, WSPR effectively doubles the available average output power from a given transmitter, compared to Opera. I suppose it depends whether you are more worried about corona on the antenna, or your electricity bill ;-)

I think it is interesting that there is only a small difference between "average" and "top 10" operators - down to about 70% correct copy, there appears be less than 1dB  between "good" and "average". Surely any lower levels of accuracy would be pretty useless for communicating information, even in an amateur context. This suggests the "human factor" in QRSS reception is perhaps quite a small factor.

Cheers, Jim Moritz
73 de M0BMU

If you used peak power (ie. the same transmitter amplitude), the curve
plotted for Opera will have to move 3dB to the right, making it more
comparable with WSPR - and then more as one would expect.

Given the similarity of the error correction overhead for Opera and
WSPR,  and nearly matching symbol rate for OP2 ,and that OOK and FSK
have comparable error rates for the same mean power, suggests the two
modes should give roughly similar performance.

Only 27 responses, that doesn't seem very many compared with the
numbers that monitor this reflector.

Andy  G4JNT


On 8 February 2012 16:00, Rik Strobbe <Rik.Strobbe@fys.kuleuven.be> wrote:

Dear all,

the results of the "QRSS3 challenge" can be found at
http://on7yd.strobbe.eu/QRSS/
Hit refresh if you still see the old challenge.

Thanks to all who participated !

73, Rik ON7YD - OR7T

________________________________
Van: Rik Strobbe
Verzonden: donderdag 2 februari 2012 18:17
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: QRSS3 "challenge"

Dear all,



as mentioned some days ago I generated a whole series of Opera, WSPR
and QRSS3 audio with a known SNR.

For Opera and WSPR it was easy to determine the lowest SNR for a proper
decode. But for QRSS3 it is much more difficult as it depends on the
operators "sharp eye". It must be somewhere in the range of -24 to -28dB SNR
(@ 2.5kHz BW).

Today I did put all the QRSS3 screenshots in this range in a
website, where you can fill in what you see (decode) for each screenshot.

I would like to invite all of you to give it a try and send me the results
(the more entries the better the statistics).

After some time (Feb 10th) will put all results into some nice tables
and graphs and make them available.

Of course no personal (individual) results will be published. But based on
the results every participant (who keeps his results) can see where he ends.



The "QRSS3 Challenge" can be found at http://on7yd.strobbe.eu/QRSS/



73, Rik ON7YD - OR7T

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