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

paul swed paulswedb at gmail.com
Tue Dec 21 17:20:14 EST 2010


Thanks will read the link. Think I have in the past but did not have a need.
I might guess 4 db would be quite helpful in this effort.
I still have some garbage I am seeing that I will need to hunt down. But its
not within the house so that really makes things interesting.

On Tue, Dec 21, 2010 at 5:14 PM, Poul-Henning Kamp <phk at phk.freebsd.dk>wrote:

> In message <AANLkTimSQsHE+YEhhhydw2V2Edj855SszT78mpQChz0o at mail.gmail.com<AANLkTimSQsHE%2BYEhhhydw2V2Edj855SszT78mpQChz0o at mail.gmail.com>>,
> paul
>  swed writes:
>
> >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.
>
> There is a very good and simple explanation of the theory behind
> loops here:
>
>        http://www.vlf.it/octoloop/rlt-n4ywk.htm
>
> Sensitivity rises with the area of your loop, so doubling the diameter
> gives you four times the signal, which may or may not be a relevant
> low number of dB.
>
> >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.
>
> Yes, this is why you should always zoom in on the 3rd positive
> zero-crossing.  Inside the announced service areas, the skywave will
> never arrive early enough to disturb the groundwave at that point.
>
> >PS I thought the bw was +/- 10KC and even wider.
>
> Yes, it is, but the amount of actual energy once you get past
> +/- 10kHz or 15kHz is very very limited.
>
> The perfect bandwidth is where the S/N of the loran-C signal
> is 1:1, but I have never found a good way to determine that
> automatically.
>
> --
> 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.
>



More information about the time-nuts mailing list