Hi Bob. > After acquisition, it seems to do some kind of matched filtering for > "what it expects" to stay synchronized and gets better Eb/N0 performance > as a result.
You are correct. NIST encourages radio controlled clock manufacturers to employ bit and frame averaging techniques to improve decoding accuracy. The frame averaging and the "sanity checks" that take place in firmware take several minutes _under good reception conditions_ to complete. WWVB reception quality normally improves at night due to better D layer signal propagation (and naturally lower noise levels). While every amateur text I've come across states that the D and E layers disappear at night, they, in fact, do not. They rise to higher altitudes and remain ionized through background cosmic radiation. It is this lightly ionized D-layer that makes LF reception possible beyond the normal range of surface wave propagation at night. Oddly enough, I have my K2/100 building experience to thank for discovering this. 73, de John, KD2BD Visit John on the Web at: http://kd2bd.ham.org/ . . . . __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com