Dear LF Group,
Alberto wrote:
Just a remark. If you want to dig deep into the noise, you must use
resolutions of 5 or 10 milli Hertz. At these resolutions the span covered
by a spectrogram is at maximum a couple of Hertz, so the 10 or 20 Hz
spread would mean that the biggest part of the stations will be outside
the screen.
73 Alberto I2PHD
Of course, it's a question of degree - if 40milliHz does not produce
a signal, you could always try a narrower resolution. It does not
really matter if the dots merge together if the purpose is only to
identify a signal is present.To facilitate this, the signal I intend to
use will have about 5 90s dashes and spaces, followed by a
"missing" dash. Hopefully, this will make it a bit more distinctive,
and if viewed at higher resolution, the dashes will merge to
produce one long dash and a shorter space. I think this should be
easy to set up using ON7YD's QRS keyer software in beacon
mode, which will also do normal CW ID's
How narrow a frequency range we can use depends on how
accurately the TX frequency can be set - my synthesiser does
0.1Hz steps, and if everybody had the same, quite a few people
could fit into 2Hz bandwidth. But whether this can be done depends
on the equipment at the individual stations involved.
Since Larry's signal is visible with quite good SNR at times in
42mHz resolution, and VE1ZJ has seen several signals with 0.3Hz
resolution, I think 42mHz resolution might do the job. If it does not,
it will certainly take a major re-think to achieve a QSO!
Cheers, Jim Moritz
73 de M0BMU
|
