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Re: [Discuss-gnuradio] multi-rtl phase synchronization
From: |
jmfriedt |
Subject: |
Re: [Discuss-gnuradio] multi-rtl phase synchronization |
Date: |
Fri, 7 Jul 2017 13:42:21 +0200 |
> The I/Q plot show complex cross-correlation between two noise signals at
> 100 MHz center frequency (2.4 MHz bandwidth noise). The phase of the signal
> can be converted into time and Allan deviation, but I never did. I was just
> happy to see a straight line.
I continued the measurement this morning after having the temperature of the
dongles
stabilized overnight: I gain a factor 10 stability on a 2 hour measurement:
http://jmfriedt.sequanux.org/3allan.pdf
Actually I just discovered something fascinating: I was contemplating which
radio
source would be best suited for the passive radar experiment. Not being able to
find any suitable source while scanning the environment with a yagi antenna, I
decided
to tune to the 143.05 MHz frequency of the GRAVES [1] bistatic emitter which
happens not to
be too far away. To my great surprise, after replacing the quartz (drifting far
too much)
with a hydrogen maser referenced synthesized tuned to 28.8 MHz, I get amazing
doppler
shifted traces of reflectors between the emitter and my receiver. I didn't
expect
such a low quality receiver to be able to extract this signal: example of a
waterfall trace
at http://jmfriedt.sequanux.org/graves.pdf
JM
[1] https://en.wikipedia.org/wiki/Graves_%28system%29
--
JM Friedt, FEMTO-ST Time & Frequency/SENSeOR, 26 rue de l'Epitaphe,
25000 Besancon, France