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Re: LF: DK7FC WSPR15

To: [email protected]
Subject: Re: LF: DK7FC WSPR15
From: Stefan Schäfer <[email protected]>
Date: Sat, 28 Sep 2013 14:28:24 +0200
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Hi Jay, LF,

Am 28.09.2013 03:06, schrieb [email protected]:
Stefan

Memory fuzzy here ... not sure if I've seen a -40 snr on your signal in the past. Do you recall?

2013-09-28 00:30  DK7FC  0.137610  -40  0  JN49ik  1  W1VD  FN31ls  6099  295
Jay W1VD  WD2XNS  WE2XGR/2 WG2XSR/2

Yes i do. When you search the database for my call, last 2 weeks and sorted by SNR you will see that -40 is rare. But even -41 is possible! See:

Timestamp Call MHz SNR Drift Grid Pwr Reporter RGrid km az
 2013-09-25 00:00   DK7FC   0.137610   -41   0   JN49ik   1   RW3ADB   KO85ro   2045   59 
 2013-09-26 21:00   DK7FC   0.137610   -41   0   JN49ik   1   RW3ADB   KO85ro   2045   59 
 2013-09-23 17:00   DK7FC   0.137610   -40   0   JN49ik   1   SV8RV   KM07ks   1621   139 
 2013-09-25 22:00   DK7FC   0.137610   -40   0   JN49ik   1   4X1RF   KM72ls   2850   121 
 2013-09-21 18:00   DK7FC   0.137610   -40   0   JN49ik   1   R3LW   KO54mq   1626   60 
 2013-09-18 19:00   DK7FC   0.137610   -40   0   JN49ik   1   RW3ADB   KO85ro   2045   59 
 2013-09-23 06:30   DK7FC   0.137610   -40   0   JN49ik   1   UW8SM   KN28iv   1163   87 
 2013-09-28 00:30   DK7FC   0.137610   -40   0   JN49ik   1   W1VD   FN31ls   6099   295 

RW3ADB usually has rather poor RX results (often 10 dB lower SNR than other RX stns close to him). That supports my thought that the decode level appears even lower if there is QRM in the passband.

One could make a test: Use a white noise generator with a high level and a notch at 136.610 Hz (my TX QRG), maybe 10 Hz notch BW. My signal must be close to the decode limit. The rest of the 200 Hz wide passband of WSPR should be covered with noise, maybe 20 dB above my signal. Theorectically there should be a decode but the SNR must be terrible, maybe you can get -42 dB SNR. That would be a new record, hi :-)

73, Stefan/DK7FC
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