[time-nuts] Simulating LORAN-A GRI Timing Generator

paul swed paulswedb at gmail.com
Sat Jan 8 10:33:41 EST 2011


The goniometer that I remember was to allow a controlled phase change for
measurments. It was inside the rcvr.

On Sat, Jan 8, 2011 at 10:28 AM, J. Forster <jfor at quik.com> wrote:

> > Loran c was complicated by the fact that there were phase reversals in
> the
> > patterns that had to be emulated it doubled the size of the code. But to
> > answer your question John its all done in simple readable basic language.
> > Think of it as a endless loop pattern. The real trick is using a good
> > reference. I think Magnus said 10 KC. What you do is count the 10 KC
> > reference. Using a Parallax SXB chip that can run all the way up to 80
> > Mhz.
> > The code runs so fast that 99.9% of the time the micro is just waiting
> and counting edges.
>
> OK. Thanks. You talk to the uP with a dumb terminal program?
>
> > I like to create dumb simple stupid, reliable as heck programs like that.
> > The Loran C sim allows the Austrons to compare to their limit of 1 e -13.
> > There is a bit more cleverness in the C simulator external to the
> > program.
> >
> > I thought there were different frequencies at about 1.8 Mhz.
>
> There are 3 between 1.8 and 2.0 MHz, one higher that was mostly unused.
>
> > I remember the gone-ometer (I still think thats a disease sailors can
> > get), green crt black box about 2 ft tall.
>
> That's for a DF loop, no? Was that used on the LORAN receiver? If so,
> that's news to me. The crossed roughly 4' loops were common on ships, but
> I didn't think they were LORAN antennas.
>
> > If you really wanted to do a location you might need 2 or 3 chips at
> > different GRIs and phases. But at $3.56 not a really big deal. Lastly
> > there
> > must be some overall sync relationship between the chains that has to be
> > maintained I might guess.
>
> I'm not sure about inter-chain sync, but IMO it does not matter much.
>
> > Oddly enough I emailed the group several times at the ship and never
> > received a response.
> > Figured they were all set.
> > Regards
> > Paul.
>
> If you're interested, I can make sure you talk to the right person.
>
> Best,
>
> -John
>
> ===============
>
>
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