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

[<hvanesce@comcast.net>]

Paul and Stefan,

Nice work, including parameters and modeling. Was the LWPC TX antenna angle 
parameter fairly close to actual angle?

73,

Jim AA5BW 

-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org 
[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Paul Nicholson
Sent: Monday, January 2, 2017 2:20 PM
To: rsgb_lf_group@blacksheep.org
Subject: Re: VLF: Back on 5.17 kHz / 58 km...


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
 > Duration: 12h, 26m, 40s
 > Antenna current: ~ 200 mA

Looks good.

Last night the carrier 2017-01-01_17:00,+44800 at 5169.99975 Hz measured 0.135 
fT but the signal is spread across 70uHz for some
reason.   It may decode at Eb/N0 between 3 to 5dB, hard to say.

Allowing for perspective I tweaked the building separation to 45m and the 
height of the service rooms to 3.5m to get 412pF and effective height 13.1m.  A 
little better but still a long way from 480pF.

Rrad is about 160u ohms so expecting 6.3uW.

LWPC says 0.088 fT daytime and 0.124fT nighttime.

Measured: Daytime average 0.095fT, nightime  0.135fT

I wouldn't rely on either LWPC or my measurements to better than
+/-50% and that is probably generous.  But it's nice to see we are
in the right ballpark.

--
Paul Nicholson
--