Re: VLF: 3 carriers near 5170 Hz

[Markus Vester <markusvester@aol.com>]

Hi Stefan,

with three carriers, you can minimize the peak-to-average ratio by optimizing relative phases. When all three are in equi-phase, the maximum voltage will be 3 times that of a single carrier (+9.54 dB). Shifting the central carrier by 90° will bring that down to sqrt(5) = 6.99 dB. Thus at same given PEP, 2.55 dB can be gained.

No idea why the middle line could have split up.

Best 73,
Markus  
  


-----Ursprüngliche Mitteilung-----
Von: DK7FC <selberdenken@posteo.de>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Fr, 27. Okt 2017 20:51
Betreff: Re: VLF: 3 carriers near 5170 Hz

Hi Paul,

oops, that is strange. Maybe the PA is a bit nonlinear (slightly
clipping) and the measurement is mixed up. I will try to solve that.
Well the difference between 5090 and 5170 seems not to be very much.
Would it makes sense to repeat the experiment? Tomorrow i could run it
for a longer time, e.g. 6 hours. Then there should be usable values on
each antenna and frequency.

73, Stefan

Am 27.10.2017 20:03, schrieb Paul Nicholson:
>
> Stefan wrote:
>
> > Since 13:20 UTC im running 120 mA on 3 individual frequencies:
> > 5090.005 Hz | 5130.005 Hz | 5170.005 Hz
>
> > Carriers stopped at 16:20 UTC....
>
> Received in 92.6uHz
>
> H-field (new) E-field
> 5090.005: 9.3 dB 10.38 dB
>
> 5130.005: N/A See below
>
> 5170.005: N/A 10.2 dB
>
> N/A where the signal is too weak to measure.
>
> Something wrong with 5130.005, here's the E-field spectrum
>
> http://abelian.org/vlf/tmp/171027a.gif
>
> --
> Paul Nicholson
> --
>