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Re: LF: Dual-speed WSPR

from [Markus Vester] [Permanent Link][Original]
To: <[email protected]>
Subject: Re: LF: Dual-speed WSPR
From: "Markus Vester" <[email protected]>
Date: Sun, 31 May 2015 02:07:29 +0200
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Yeah maybe. But at the moment I'd rather keep things as simple as possible, and I anyway wouldn't expect a sharp optimum regarding speed.
 
The idea is to compare the SNR of the slow sequence with the average of the two surrounding fast sequences, received by the same monitor. If the dB results were the same, we could probably exploit the full 9 dB advantage due to the lower threshold (-38 vs -29 dB), otherwise we'd have to subtract the dB difference.
 
Results from first round:
 
 2015-05-30 23:46   DF6NM   0.475791   -11   0   JN59nj   0.5   DL4YHF   JO42fd   359   330 
 2015-05-30 23:30   DF6NM   0.475824   -8   0   JN59nj   0.5   DL4YHF   JO42fd   359   330  
 2015-05-30 23:28   DF6NM   0.475791   -11   0   JN59nj   0.5   DL4YHF   JO42fd   359   330
=> WSPR-15 SNR happened to be 3 dB better!
 
 2015-05-30 23:46   DF6NM   0.475790   -15   0   JN59nj   0.5   SM2DJK   KP03au   1694   15
 2015-05-30 23:30   DF6NM   0.475823   -13   0   JN59nj   0.5   SM2DJK   KP03au   1694   15 
 2015-05-30 23:28   DF6NM   0.475790   -14   0   JN59nj   0.5   SM2DJK   KP03au   1694   15
=> WSPR-15 shows 1.5 dB better.
 
 2015-05-30 23:46   DF6NM   0.475792   +1   0   JN59nj   0.5   DG3LV   JO53gv   502   356 
 2015-05-30 23:30   DF6NM   0.475824   -2   0   JN59nj   0.5   DG3LV   JO53gv   502   356 
 2015-05-30 23:28   DF6NM   0.475792   -8   0   JN59nj   0.5   DG3LV   JO53gv   502   356
=> WSPR-15 shows 1.5 dB better.
 
This is an unexpected result, implying that the advantage of WSPR-15 would be more than 9 dB, instead of less. But on the other hand the dB values may not be telling the whole story, because the threshold for a fading signal might still be higher than -38 dB.
 
All the best,
Markus (DF6NM)

From: DK7FC
Sent: Sunday, May 31, 2015 1:33 AM
Subject: Re: LF: Dual-speed WSPR

Markus,

What about the old slow-WSPR by DF6NM? It could be useful to try WSPR-4 for experiments. There is not just 2 and 15. And WSPR-120 on VLF... No problem!

73, Stefan

Am 31.05.2015 01:28, schrieb Markus Vester:
To allow SNR comparisons at different speeds, I will transmit a mixed-mode beacon tonight. It will consist of two WSPR-2 sequences, before and after a WSPR-15 sequence on each odd half hour:
 
hh:28 - hh:30: WSPR-2 475.790 kHz
hh:30 - hh:45: WSPR-15 475.823 kHz
hh:46 - hh:48: WSPR-2 475.790 kHz
 
Transmitter power is currently 25 watts into an antenna with 2% efficiency. Am listening to both modes at all other times.
 
All the best,
Markus (DF6NM)
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