Stefan,
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 http://www.qsl.net/on7yd/136narro.htm
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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