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I don't think its stability Andy , could be
step response and settling time , the
new U3 kit uses a PLL and produces , what
was thought to be key click's but
is PLL settling time , out of lock
detectors would normally inhibit output , but for a
phase cont system .. there's a conflict of interests , no
problem keying Opera as its a single tone ,
fixed frequency , but the mfsk modes have
problems associated .. the original used DSS
, PLL's may be the
wrong way to go I think for a exciter , where large
step changes in frequency are commanded ,
after all , we know why DDS's
where first devised : )
G,
Sent: Wednesday, July 01, 2015 6:22 PM
Subject: Re: LF: what causes this on wspr
Yep - I missed the fact it was over a minute long .
The sidebands are 12Hz (not 8Hz as I said before) which seems a bit close
for any synth instability. Nothing is that slow surely.
So a bit of a mystery in that case. Still reckon it looks like
CW though. Hard on -off keing generates a spectrum at harmonics of
the clock frequency
Andy
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