From: Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Date: Wed, 8 Feb 2012 19:13:45 +0100
Thread-Topic: LF: QRSS3 "challenge" results
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Hello Andy,

I had the same thought, mean power or peak power ?
I did choose for peak power as this is the "real world" limitation for high=
 efficiency class D or class E amplifiers.
At +80% efficiency these PA's have no problem with 100% duty cycle.
If you take mean power Opera will indeed perform 3dB better.

73, Rik  ON7YD - OR7T

________________________________________
Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org=
] namens Andy Talbot [andy.g4jnt@gmail.com]
Verzonden: woensdag 8 februari 2012 17:59
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: QRSS3 "challenge" results

Hi RIk -

one comment / question I have ...
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.

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 result=
s
> (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 o=
n
> the results every participant (who keeps his results) can see where he en=
ds.
>
>
>
> The "QRSS3 Challenge" can be found at http://on7yd.strobbe.eu/QRSS/
>
>
>
> 73, Rik  ON7YD - OR7T=