Hi If you were starting from scratch there are a lot of things you could do. If the intent is to put out something a Loran receiver will recognize ... not so much.
Bob On Oct 5, 2010, at 6:44 AM, Poul-Henning Kamp wrote: > In message <b69fdcaf-2b39-4575-b5cd-66a87fa1b...@rtty.us>, Bob Camp writes: > >> Even though it's pule, the RF power is way beyond the sub 1 W >> outputs currently contemplated on those bands. Signal to noise >> *does* matter. > > You know, there are other ways to skin that cat these days. > > Old-time signals had to be grossly inefficient because the receivers > were inefficient, in particular the "ear-wristwatch" kind of time > receivers. > > These days we have spread-spectrum modulation, and if our only goal > is to transmit a timestamp, you can spread pretty wide and far and > need very little power to produce a receiveable signal at long > distances. > > The QRSS hams are playing around with numbers like 17,840,000 miles > per watt, and all it takes to turn that into a time/frequency > services is a spreading function with a really good autocorrelation. > > Obviously, you will not get second by second measurements, but the > measurements you do get, say once per hour, will have much higher > precision because of the averaging that goes into them. > > And equally obvious: propagation effects will take their toll, but > still... > > Somebody with a license should try that on 137kHz... > > Poul-Henning > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > p...@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. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.