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.