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Re: LF: Phase shifts on 137.777 kHz

To: [email protected]
Subject: Re: LF: Phase shifts on 137.777 kHz
From: Paul Nicholson <[email protected]>
Date: Sat, 21 Nov 2015 21:36:57 +0000
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I'll look out for your signal Joe, although that's
a complicated pattern to look for unless we know
just when you start your sequence.  But if someone
gets a strong enough signal it should be a clear
pattern on a spectrogram.

I've made some timing improvements today and things
are working a bit better.

The background noise comes up about 6dB after sunset
and the extra noise is causing problems with the PPS.
It works a lot better during the day!

I need to get into the shed to adjust levels but if
I open the door, freezing air will rush in and upset
the sound card clocks badly.

> If I scan ebcode.txt & use phase=bit*pi,
> how long should my bits be keyed?

Difficult to say without a carrier measurement beforehand.
I'd guess somewhere between 5 and 10 seconds but I haven't
got a lot to go on without seeing some carrier.

> Is synchronisation against UT critical?

Yes you'll need to set your PC clock within a tenth
of a symbol period, which is quite easy with slow
symbols.  And you'll need to announce the start time.
There's no way to search for a signal.

Right now I see nothing on 137.777000 but we may have
to wait until 22:00 or 23:00 for the path to be dark.
--
Paul Nicholson
--

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