Brooke, I proposed a platform driven by a synchronous motor referred to a cesium standard. On this platform is an arrangement to project an attenuated image of the sun onto a mirror that is attached to a galvanometer. Light-beam galvos used this kind of arrangement. The mirror projects the solar image onto a split detector, such that the output of two photocells cancels when the image is centered. The detector drives a servo to keep the image centered using the mirror galvanometer. You'll also need a vertical servo to track the sun through the day.
The signal to the galvo is proportional to the deviation of the suns image. Remove the equation of time (a few percent) and you have the deviation from solar time. Do a lot of these and you can apply statistical methods to find the Earth's wobbles. Sounds like great fun, but beyond my capabilities. A rotating platform with no error in angles, for instance. A clear field of view, for another. Regards, Bill Hawkins -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brooke Clarke Sent: Sunday, November 05, 2006 1:29 PM To: Tom Van Baak; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Earth: An Oscillator and Frequency Standard Hi Tom: Thanks for the lab test report on the earth frequency standard. Since there are a number of frequency/time standards that have much better performance I'd like to find a way to directly measure the performance of the earth standard. I've thought about a telescope looking at stars or maybe a photo detector to look at the light from the closest star to the earth frequency standard. Do you have any ideas on how to make these measurements? Have Fun, Brooke Clarke w/Java http://www.PRC68.com w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml http://www.precisionclock.com Tom Van Baak wrote: >>>Anyway, how do you compute the Allan Deviation of a sun dial? >>> >>> >>Oh, God, now someone's going to do it... >> >>John >> >> > >Well, yes, thanks for asking! I did it a year ago. > >The lab report on earth, including Allan deviation is at: > >http://www.leapsecond.com/museum/earth/ > >/tvb > > > _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts