<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body>Being in the middle of re-reading "a brief history of time" (I received an illustrated edition for xmas, it's awesome), I can't help but wonder, gravity waves? <br><br>-------- Original message --------<br>From: Pete Soper via TriEmbed <triembed@triembed.org> <br>Date: 1/28/2016 11:39 AM (GMT-05:00) <br>To: Triangle Embedded Interest Group <TriEmbed@TriEmbed.org> <br>Subject: [TriEmbed] that recent 14usec GPS error wrt UTC <br><br>Recently the time info from the GPS satellite system experienced a hiccup and its reckoning of UTC time was momentarily off by about 14 microseconds. This got a lot of people's attention, because they're of course used to this stuff being very precise and there's a lot of heavy duty dependence. Paul Boven figured this out and his explanation was put on today's time-nuts list digest:<br><br>"We were able to track this down today at Meinberg.<br><br>The problem was that some satellites were sending invalid UTC correction<br>parameters. The UTC correction parameter set not only contains current<br>leap second information but also coefficients (A0, A1, WNt, tot) for a<br>polynomial used to compensate the fractional difference between GPS time<br>and UTC(USNO).<br><br>Today the faulty satellites sent about 13.7 microseconds for A0, and WNt<br>as well as tot were both 0. So when the GPS receiver updated its UTC<br>correction parameters from a faulty satellite the UTC correction jumped<br>from close to 0 to about 13.7 microseconds, which let the UTC time step,<br>and when the GPS receiver received the UTC parameter set from a healthy<br>satellite the UTC time stepped back."<br><br>-Pete<br><br><br>_______________________________________________<br>Triangle, NC Embedded Computing mailing list<br>TriEmbed@triembed.org<br>http://mail.triembed.org/mailman/listinfo/triembed_triembed.org<br>TriEmbed web site: http://TriEmbed.org<br></body></html>