Hello Alberto,
phase coherence maybe a bit tricky.
I am not a mathematic expert, but just intuitive I would say that
knowing the exact time of begin and end of a dot could be used to
improve SNR.
One possibility that comes to my mind :
Assume
* a series of dot sequence (let's say 5 = .....)
* a dot length of 1 minute
* each dot starts exactly at the full minute
Now take one FFT every second, with the samples from the last 60
seconds. the subsequent FFT's should show a triangular wave that has a
period of 2 minutes and is in phase to the minute rytme.
Maybe using the right technique (kind of FFT of the FFT ?) one could
detect this 2 minute triangular wave at signal levels that are to weak
to bring up the dots with ARGO or similar software.
Makes this sense or it is just a stupid idea ?
73, Rik
Citeren Alberto di Bene <[email protected]>:
> "TX/RX synchronisation" would reduce the time occupied by FFT by
100
> or more (from several FFT/sec to 1 FFT/min). The "calculation
power"
> that becomes available could be used to improve SNR. But How ?
Maybe, if the Tx and Rx can be brought into phase coherence (what
about
ionospheric effects ?)
then the FFT could be replaced by techniques working in the time
domain,
like correlation and
Wiener or matched filtering... maybe someone more expert than me on
the
subject would comment.
73 Alberto I2PHD
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