I should add you can use GPS receivers for accurate time, the satellites have cesium clocks on board and probably synch to NIST also.
Question: The naval observatory also has a time standard -- why do we need two, and what's the difference? -----Original Message----- From: Jed Rothwell [mailto:[email protected]] Sent: Wednesday, March 30, 2011 2:28 PM To: [email protected] Subject: Re: [Vo]:Another problem with electricity in Japan, the AC frequency varies [email protected] wrote: > I wasn't talking about clocks with synchronous motors, but rather electronic > clocks that use the line frequency directly&/or for synchronization, and I > think there are still quite a few of those. I know what you mean. I used to have one. I think it burned up one day. I do not recall seeing any for sale in stores for 30 years or so . . . There are some web sites about this, in which line frequency electric clocks are referred to as "antiques." Wall clocks these days use AA batteries, don't they? - Jed
