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AW: LF: "Gain" between qrss3 and qrss10?

To: <[email protected]>
Subject: AW: LF: "Gain" between qrss3 and qrss10?
From: Stefan Schäfer <[email protected]>
Date: Fri, 11 Dec 2009 21:49:42 +0100
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Thread-index: Acp6aN9gFFwHgWhGRrClau0pefh3nAAOiCOg
Thread-topic: LF: "Gain" between qrss3 and qrss10?
Rik, LF, 
Tnx for your detailed explanations! I will not forget it any more! :-)
CU tmw or Sunday!
Stefan / DK7FC
PS: I just bought my new and biggest kite ever: 8,1m^2, that needs a 500kg 
braid and just 1,5bft...

-----Ursprüngliche Nachricht-----
Von: [email protected] 
[mailto:[email protected]] Im Auftrag von Rik Strobbe
Gesendet: Freitag, 11. Dezember 2009 14:46
An: [email protected]
Betreff: Re: LF: "Gain" between qrss3 and qrss10?


if output power is constant and the noise (at RX) is uniform then the 
SNR is directly related to the RX bandwidth, what must be at least 
equal to the useful bandwidth of the TX signal.
The required bandwidth for QRSS30 (0.033Hz) is ten times smaller than 
for QRSS3 (0.33Hz), so QRSS30 should have a 10dB better SNR. QRSS10 
(bandwidth 0.1Hz) is about 5dB better tha QRSS3 and 5dB worse than QRSS30.
The above also assumes that both RX and TX stability are sufficient.
Have a look at
Another limit is the "stability" of the ionosphere, causing doppler 
effect and thus limiting the minimal bandwidth. Most of the time on 
137kHz one can go as slow as QRSS120, but at 10MHz QRSS10 is the limit.

73, Rik  ON7YD - OR7T

At 13:29 11/12/2009, you wrote:
>Dear LF,
>Does anybody know about the "gain" between QRSS3 and QRSS10 or 
>QRSS30? I mean, if the noise in both cases is equal, how much can I 
>reduce my tx pwr when switching from qrss3 to qrss10? Or isn't it 
>possible to give such a relation?
>And: Was there ever a TA QSO in QRSS3?
>I am new on the reflector, sri ;-)
>Stefan / DK7FC

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