Paul, I'd bet there are 50+ LORAN timing receivers in the Boston area that could receive and lock to an erzatz 5W signal from a simulator and small amp.
-John ============= > A great thread by everyone. Oh to make the loran receivers work. But that > is > indeed the past. Can not hear Europe on east coast. > But the question really is, what do you want to accomplish? I don't think > its a time stamp. Its just to easy to get it from GPS or the network. But > that could be a secondary use. I believe the primary goal would be > frequency > distribution with perhaps a tick. > If this is the goal then I am 100% in agreement that there are far more > efficient modulation and recovery methods today. The trick is you need > something that does not effect the accuracy of the timing and may improve > the various transmission issues at these frequencies. By the way this list > has a heck of a brain trust so its very very possible. > Someone mentioned spread spectrum. Thats very interesting as it is what > GPS > uses and could work at these lower frequencies. > Like the "Hey this is just telemetry" comment. You know the FCC does > indeed > give temp authorization for quite long periods of time. Years in fact. > So I would be in the keep it simple mode. > Great a single carrier with a id every 10 min. Maybe that could be waved > to > 1 per hour or 24 hours. Unfortunately then we have nothing better then > wwvb. > The modulation method may be key and then what freq we would use. BPSK at > higher frequencies is also impressive. > My first contact was in the indian ocean on 5 whats from boston. > Regards > Paul > WB8TSL > > > On Tue, Oct 5, 2010 at 6:59 AM, Bob Camp <li...@rtty.us> wrote: > >> 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. >> > _______________________________________________ > 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.
