Re: LF: VO1NA 8270.0075 Hz, 82 Hz phase

[Andy Talbot <andy.g4jnt@gmail.com>]

If you're in waveguide close to cutoff, the phase velocity changes very fast with frequency.

That could be what you're seeing

Andy

www.g4jnt.com

On 12 September 2018 at 16:37, Markus Vester <markusvester@aol.com> wrote:

Hi Joe,

the bottom of the ionosphere is higher at night, so the geometrical length of each hop increases. In that sense the phase variation is indeed a Doppler shift, produced by a receding / approaching mirror.

Normally at VLF this would probably be formulated in terms of phase velocity for waveguide modes instead of rays and hops, but the underlying physics is the same. Phase observations on MSK signals and fringing patterns on 19.8 kHz indicate that VLF waves are ~ 0.2% slower at night.

What is strange though is that at ELF frequencies the change seems to be the other way round, and much stronger. From simultaneous observations of ZEVS carrier phase in Amberg and Moonah, we surprisingly found that the phase velocity at 82 Hz appears to be 15% (!) faster at night.

Best 73,
Markus (DF6NM)

-----Ursprüngliche Mitteilung-----
Von: jcraig <jcraig@mun.ca>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Mi, 12. Sept 2018 16:06
Betreff: Re: LF: VO1NA 8270.0075 Hz

Hello Markus and Paul, group,

That's a much better explaination than Doppler shift. What would cause a
180 degree phase shift? Is there an XOR gate in the sky.

A few more dB will depend on getting some plastic machined. Hopefully
this will be before the end of winter.

The TX is off since ~10ut due to lightning in the forecast.

73
Joe VO1NA

On Tue, 11 Sep 2018, Markus Vester wrote:

> That continuous trace on Paul's spectrogram is impressive - great work!
>
> Attempting to extract a long spectrum from Paul's data creates a split peak at +-12 uHz from the center, suggesting a repeating near 180° phase difference between day and night.
>
> A close look on our Bavarian 31 uHz spectrograms seems to bring up some faint traces on the right frequency, but to be more sure we still need a few dB less noise, or more ERP.
>
> Best 73,
> Markus (DF6NM)
>
>
> -----Ursprüngliche Mitteilung-----
> Von: jcraig <jcraig@mun.ca>
> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
> Verschickt: Mo, 10. Sept 2018 21:33
> Betreff: Re: LF: VO1NA 8270.0075 Hz
>
>
> I've not been mucking with the tx or tuning so perhaps Mother Nature has
> provided an ERP improvement -- the wx has been quite dry recently.
>
> Thank-you for the report and the spectrogram service. It keeps me
> entertained, especially since it seems impossible to see my own
> sigs with a remote setup at distances greater than about 10 km.
>
> Been playing with vt tools and a cheap sound card.
>
> 73
> Joe VO1NA
>
> On Sun, 9 Sep 2018, Paul Nicholson wrote:
>
> VO1NA from Newfoundland with 10uW must hold the record for
> the longest running VLF transmission!
>
> Coming in well the last couple of days -
>
> http://78.46.38.217/fbins3.html#p=1536487200&b=280&s=sp&m=cardioid&w=r&h=62&z1=0.34&z2=0.64&c=1
>
> An ERP improvement, or good propagation?
>
> --
> Paul Nicholson
> --