Return to KLUBNL.PL main page

rsgb_lf_group
[Top] [All Lists]

Re: VLF: EbNaut transmissions on lower frequencies?, pre-tests: 6.47kHz

To: [email protected]
Subject: Re: VLF: EbNaut transmissions on lower frequencies?, pre-tests: 6.47kHz
From: DK7FC <[email protected]>
Date: Fri, 14 Oct 2016 15:42:06 +0200
In-reply-to: <[email protected]>
References: <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
User-agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3
...another thing about phase stability on the 46km band. Take a look at http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
At night you can see the "local effects", frequency dependent minima and maxima of the strength of the QRN. Arround 5:30 UTC (sunrise) these effects disappear. The effects could cause strong phase instabilities.
Out best result was 10 characters 8K19A with 100s symbols, i.e. 21 hours for the transmission. So it must have been during the night as well. But this was May, 20th, so the night was short!
We'll see...

73, Stefan

Am 14.10.2016 15:23, schrieb DK7FC:
Hi Paul,

Hmmmm, wellll, maybe there are some propagation behaviours on the band that we don't know yet. Could summer work better than winter, despite the higher average QRN levels? Who has the privilege to do private-research on a 'new' band? We!
So, i started a new message:

f = 6470.00000 Hz
Start time: 14.10.2016   13:15:00 UTC
Symbol length: 60 s
Characters: 3
CRC 16
Coding 8K19A
Duration: 6h, 56m, 0s

Antenna current: 290 mA (ish)

The QRN is very high now on VLF. But maybe this just indicates that propagation is better??? The QRN looks like as coming from far away, no local effects (yet).

Any news from the previous tests?

73, Stefan




Am 12.10.2016 21:35, schrieb Paul Nicholson:

> f = 6470.00000 Hz
> Start time: 12.10.2016   14:30:00 UTC
> Symbol length: 40 s
> Characters: 3
> CRC 16
> Coding 8K19A

No decode, just a false hit ' WV' at Eb/N0 = -0.7.

Strange.  According to carrier measurements this should
be an easy decode at around +3db.

More carrier measurements: night signal phase lags daytime
by 60 degrees.  Night amplitude is about 0.1 fT.

The 16K25A 15 char 140 second message should decode at
about Eb/N0 +6dB.   So far no improvement on the partial
decodes, next to try is correcting for that 60 deg diurnal.

--
Paul Nicholson
--

<Prev in Thread] Current Thread [Next in Thread>