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I made three complete transmissions of the sequence "G4JNT PSK
CW " and most of a forth one until 2022z This sequence had 124 dot
intervals, including end of text spaces, so repeated every 20.67 minutes.
Power output was turned down a bit to 450 Watts for this test.
The phase wobble is due to the GPS locked source in
use, it was really designed for longer signalling intervals than
this. The PLL is not fully optimised and has a bandwidth of a
few seconds, so phase jitter measured over this sort of interval will
be seen. However, if it were possible to integrate over the 10 second dot
period then make a descision at the end, the jitter would have an almost
insignificant effect even at this signalling rate.
Andy G4JNT
phase meter shows a slant over an 800 second
obvervation period, but with a bit of imagination the text can be decoded.
See attached screenshot.
The transmission started at 1900 utc in the
diagram at 't=0', on the left side.
A certain amount of "phase jitter" is
visible but I'm not sure if it was the quite weak signal affected by noise or
Andy's GPS-locked generator. Another screenshot with "L.O."-frequency
increased by 2 milliHertz is also available on request.
Regards,
Wolf DL4YHF.
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