Path: utzoo!utgpu!watserv1!watmath!att!emory!gatech!usenet.ins.cwru.edu!agate!ucbvax!udel.edu!Mills From: Mills@udel.edu Newsgroups: comp.protocols.time.ntp Subject: Re: wwvb.isi.edu 15 minutes off? Message-ID: <9102241722.aa29352@huey.udel.edu> Date: 24 Feb 91 22:22:18 GMT Sender: daemon@ucbvax.BERKELEY.EDU Distribution: inet Organization: The Internet Lines: 20 Tim, A closer look at wwvb reveals that it was wildly wobbling to and fro in frequency where the rate of change in frequency varied up to 1000 ppm in an hour(!) I strongly suspect the radio simply lost signal, which is not an uncommon event with these things, whereupon the radio tracking loop went nuts. All timecode receivers have the problem of what to do when the signal dies, which is common in WWV/H receivers like PSTI/Traconex and Heath and to a lesser degree in WWVB receivers, but most receivers (Heath excepted) can hold the fort to maybe a few ppm over the loss interval. I have keenly observed the Traconex receiver, which commonly warps a few milliseconds near sunup and sundown, the Spectracom 8170 and the True-Time GOES receivers, which don't warp, but can wander a few milliseconds over a day under signal- loss conditions. However, the wwvb behavior, assuming it was caused by signals fading into the muck no silicon is broken in the circuitry, is clearly beyond any reasonable nominals. I will take this issue up with Spectracom. Dave Brought to you by Super Global Mega Corp .com