Re: LF: More EbNaut 137.777 - phase plot

[jcraig@mun.ca]

Paul and Markus,
Critique on the sigs are most welcomed.  Getting a decode from Paul
on a dead preamp is very satisfying!

Lets do a repeat of last night's 8 s 2c starting in 5 mins.

73
Joe VO1NA

On Mon, 7 Dec 2015, Markus Vester wrote:

> Paul,
>  
> that's an interesting phase plot! Although it's probably hard to completely 
> rule out a contribution from TX oscillator drift, the 3.5-cycle day-night 
> change seems quite plausible.
>  
> Attached is a plot from a recent Loran-C operation from Wildwood, NJ. The top 
> plot shows signal strength in two ways (red is the total received pulse energy, 
> magenta the narrowband 100 kHz amplitude). The blue plot is continuous phase, 
> also showing a similar 3.5-cycle phase advance during the morning hours. Given 
> the larger distance (6595 km) and lower frequency (100 kHz), this is obviously 
> a very nice match to your VO1NA result.
>  
> All the best,
> Markus (DF6NM)
>
>  
> -----Ursprüngliche Mitteilung-----
> Von: Paul Nicholson <vlf0403@abelian.org>
> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
> Verschickt: Mo, 7 Dez 2015 12:27 am
> Betreff: Re: LF: More EbNaut 137.777 - TA slot
>
> It was a few hours before I got to the rx to retrieve the
> battery so it continued on an almost dead battery and recorded
> two more messages.
>
> VO1NA 2015-12-05/06 16K21A 5S 5C QRO
>
>  start  Eb/N0  Freq
>
>  13:30  13.0   -222 uHz
>  15:00   3.1   -256 uHz
>  16:30   3.9   -482 uHz
>  18:00  15.1   -558 uHz
>  19:30  17.3   -228 uHz
>  21:00  14.2   -330 uHz
>  22:30  18.7   -262 uHz
>  00:00  14.8   -253 uHz
>  01:30  17.0   -293 uHz
>  03:00  22.4    -41 uHz
>  04:30  20.8   -208 uHz
>  06:00  13.0   -216 uHz
>  07:30  17.0   -276 uHz
>  09:00   3.1    +20 uHz
>
> Partial reception at 10:30 gave enough to measure +3 uHz.
>
> I was able to measure the phase over the entire 21 hour
> recording in 5 minute averages:
>
>  http://abelian.org/vlf/tmp/151206a.gif
>
> This looks to me like propagation, not drift of the tx
> oscillator.  It's a pretty typical diurnal.  I'm plotting
> phase measured at a frequency offset of -255 uHz.
>
> I think that Joe's oscillator is actually doing very well and
> we are seeing mostly the effect of propagation.  The phase ends
> up nearly where it started and the total day/night change is
> about -1250 degrees or about -3.5 cycles.
> --
> Paul Nicholson
> --