In a message dated 12/20/99 7:21:09 GMT Standard Time,
[email protected] writes:
<< Hi All.
Can anyone explain to me why qrss is necessary on 136 khz. All the
activity that I have heard on this frequency is workable on normal speed
cw at my qth.>>
Unfortunately Mal you have not heard "all the activity", but just the
activity audible in your receivers bandwidth, even if that's 80Hz.
I could understand the use of this mode on 20 khz and
below because of a possible bandwidth consideration. If this was the
case, there are other alternatives like MSK. Commercial stations only
use the qrss method as a necessity on VLF.
Maybe there is something that I have missed, like very qrp experiments,
but the signals that I have heard do not indicate this. I have not seen
any weak signals on qrss that I could not copy aurally.
Please enlighten me please. de Mal/G3KEV
>>
Hi Mal.
Weak signal working is the main advantage of QRS and Spectrogram should offer
a 10dB advantage over your normal rx performance. Another good example of a
QSO that is only possible using QRS techniques would be one that takes place
within an environment of QRM e.g. In the many areas of Europe where Loran
is present or, as in my area, where I can operate between lines generated by
50Hz harmonics.
FFT techniques are also used in weak signal moonbounce etc.
There has been a lot written on various web sites, in the LF source book, on
this reflector and indeed in Rad Com.
But I'm sure you are aware of these things.
That Northern sense of humour......This is a wind-up. Right?
Merry Christmas
David G0MRF
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