[time-nuts] Re: Eloran long test from now to August or September.

[paul swed]

Well the 2100F seems to have started to grab something here in Boston
around 1300 local. Have a scope turned on and looking at the gated output
signal to see what might be there. Nothing all that obvious. If I get
anything it will be by skywave.
Regards
Paul

On Tue, Sep 19, 2023 at 11:18 AM Poul-Henning Kamp <phk at phk.freebsd.dk>
wrote:

> > But that said the lower in frequency the system is the harder it is to
> get
> > something to radiate.
>
> At 60 kHz the gap between ocean and the ionosphere is a waveguide,
> which bends the signal to match the Earth's curvature, so
> there is no theoretical limit to distance, as long as it is over
> an ocean.
>
> That is why the first commercial radio-telephone connection between
> USA and UK in the 1920ies used 60 kHz.
>
> At 100kHz there is no significant waveguide effect, quite the
> contrary, you get "skywave" reflections, in particular at night.
>
> Here is a recording of the "skywave dance" on a typical night at a
> distance of approx 200km from the transmitter:
>
>         https://phk.freebsd.dk/AducLoran/animation2.gif
>
> Loran-C uses the "3rd positive zero-crossing" as reference because
> it is impossible for the skywave to arrive so early, given the height
> of the ionosphere.
>
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
>