[time-nuts] LORAN C antenna thoughts from the group

[paul swed]

John I believe that it is usable certainly from the pre-amplified whip that
I picked up 90070 last night on.
The downside is you have to be awake at 0300. One of those nights.
As I mentioned my GPS comparison was not very good because I forgot to
rehook the gps antenna up to the hp3801. Doaaaa. Explains that pretty well.

Is there a real advantage to a 4 or 6 foot big loop compared to a small
loop?
I use a 3 foot loop on wwvb/preamp and that works well.

One other point on the wavefrom on loran c. It was constructed to minimize
the impact of skywave influence on the receiver. Essentially making it
easier for the receiver to distinguish between the two. Thast what I hadread
in the loran docs.
Regards
Paul.
PS I thought the bw was +/- 10KC and even wider.

On Tue, Dec 21, 2010 at 3:11 PM, J. Forster <jfor at quik.com> wrote:

> I was more interested in reducing the BW, rather than increasing it.
>
> Years ago, I bought up some of the resuidual of Appelco, a New Hampshire
> LORAN company that made units for Raytheon. Included were a bunch of
> active tunable filters, designed to "tune out" interference. However,
> there is no documentation.
>
> I was just toying with the idea that a good shielded (possibly active)
> loop, the tunable filters, and an Austron 2100F might still be usable on
> the east coast.
>
> FWIW,
>
> -John
>
> ================
>
> > In message <53187.12.6.201.2.1292957970.squirrel at popaccts.quikus.com>,
> "J.
> > Fors
> > ter" writes:
> >
> >>I remember reading somewhere that the envelope of the LORAN pulses was
> >>shaped to reduce the transmitted BW.
> >
> > The envelope is designed for two things:  sensible BW and ease of
> > production.  There is some math musing about it in the Radiation Lab
> > book.
> >
> >>Does anybody have a reference for that, and relatedly, what does the BW
> >> of
> >>the antenna have to be? Typically, loops are about 90 KHz to 110 KHz, but
> >>can that be narrowed down?
> >
> > In principle you can make it as narrow as you want, and compensate
> > for the resulting pulse-shape distortion in your receiver.
> >
> > Going much wider than 30kHz (85-115kHz) usually results in more
> > interference from CW signals than improvement to the loran signal.
> >
> > You can see a typical power spectrum at the bottom of this page:
> >
> >       http://phk.freebsd.dk/loran-c/Antenna/
> >
> > Poul-Henning
> >
> > --
> > 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.
> >
> >
>
>
>
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