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

[Paul Nicholson <vlf0403@abelian.org>]

Summing after each reception normalised to relative noise RMS 1.0;
S/N is dB in 2500 Hz;

Day tests:

              Eb/N0   S/N  Phase   RMS
 11th Nov      3.9   -62.5 -141.2  2.56
 12th Nov      4.9   -59.7 -134.3  2.01
 11th to 12th  7.5   -57.9 -137.1
 13th Nov      8.5   -55.6 -138.5  1.07
 11th to 13th  9.6   -53.8 -137.8
 14th          3.5   -61.3 -136.8  2.48
 11th to 14th 10.4   -53.1 -137.6
 15th          1.1   -64.0 -139.9  3.59
 11th to 15th 10.7   -52.9 -137.8
 16th          5.0   -60.8 -140.8  2.45
 11th to 16th 11.0   -52.2 -137.4

Night tests:

              Eb/N0   S/N   Phase
 15th Nov     -3.0   -67.8  -34.0   no decode

I wrote:

> Later I'll fire up LWPC and plot some examples of long
> distance paths.

For 1uW ERP, DK7FC to Todmorden

 http://abelian.org/vlf/tmp/1479317903_9356.png

Daytime signal -34dBuV/m corresponds to about 0.03 fT

DK7FC to vlf35 Virginia

 http://abelian.org/vlf/tmp/1479318501_18872.png

-54dBuV/m, about 20dB weaker than Todmorden reception,
would need 100 days summation to build up the same
signal.

DK7FC to Tasmania:

 http://abelian.org/vlf/tmp/1479318832_10010.png

A crazy looking diurnal. At -145dBuV/m, even a century
of summing wouldn't come anywhere close to this.

Sorry Edgar.

--
Paul Nicholson
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