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Re: VLF: Back on 5.17 kHz / 58 km...

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Subject: Re: VLF: Back on 5.17 kHz / 58 km...
From: DK7FC <[email protected]>
Date: Tue, 03 Jan 2017 13:06:28 +0100
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Hi Paul, VLF,

Thanks! That's our todays and best result so far on 58 km :-)

Do you think the phase on 5.17 kHz is more stable between day and night relative to 6.47 kHz? I would try a 24 hour transmission soon, starting either 17 UTC or 8 UTC so there is just a single day->night or night->day turn.
Just 10 dB difference after sferic blanking. In summer it can be 20 dB.
But i think it has to do with the lower frequency as well, there's just
less QRN, which also tells that propagation above 3000 km becomes much
harder.
Do you or anyone else have suggestions of what could be tried on that
band? Is there anyone else out there preparing to receive?
73, Stefan



Am 03.01.2017 09:07, schrieb Paul Nicholson:
Stefan wrote:

> f = 5170.000000 Hz
> Start time: 02.Jan.2017   17:00:00 UTC
> Symbol length: 40 s
> Characters: 5
> CRC 16
> Coding 16K25A

Received 'HELLO', BER 41.1%, constant reference phase.

Carrier Eb/N0 = +1.0 dB, S/N: 15.57 dB in 22.3 uHz,

A little weaker than expected.

S/N -64.9dB in 2.5kHz after sferic blanking.  Before the blanker,
the signal measures -74.8dB after hum removal.


Markus wrote:

> SpecLab resets the phase of it's GPS-locked signal
> generators at midnight.

Ah, that would explain it, thanks.  Now you mention it, I think
we've hit that problem before but I had forgotten.

I measure a phase advance of 131 degrees at midnight.

We had better stick to frequencies that are a whole number of
cycles per day.   That also simplifies coherent stacking of
daily transmissions.

Jim wrote:

> Was the LWPC TX antenna angle parameter fairly close to
> actual angle?

I'm not sure what you mean there.

--
Paul Nicholson
--





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