From: Brooke Clarke <[EMAIL PROTECTED]> Subject: [time-nuts] DC Voltage Ramp? Date: Sat, 03 Sep 2005 15:30:10 -0700 Message-ID: <[EMAIL PROTECTED]>
> Hi: Hi Brooke, > The actual oscillator that provides the output from a Cesium standard is > in fact a crystal whose fine tuning voltage has been locked to the > Cesium source. > > If the oscillator was run standalone and it's aging rate determined by > using GPS then if the proper voltage ramp was applied the output would > be very close to a Cesium source. This may be a linear or parabolic > ramp. It would be a bit of both actually. But not quite, the aging is not as simple that it is fully wrapped inside the model of a fixed drift rate. Proper stabilizing of the crystal temperature simplifies the model alot thought, since shift in temperature would not have the crystal beging a new aging period. Infact, you don't want to drive the crystal until you have it stabilized on temperature to avoid drift. Some measurement apparatous actually will not turn on until the crystal heating has been on for sufficient time, when it has only then the power button works. > An example is plotted at: http://www.rt66.com/%7Eshera/index_fs.htm > but for Cesium quality the tuning voltage needs orders of magnitude > smaller steps. > > The problem is coming up with the voltage ramp. I hear that the Austron > 2010B Disciplined Oscillator has steps that are too crude. Has anyone > come up with a viable way to do this? Have you read about HPs SmartClock technology? If not, this is a good time to do that. The HP Z3801A contains the SmartClock technology, and it sure monitors quite alot of things. Mine seems to fail to converge into tighter specs thought. In a simple model, you compensate for frequency error (linear phase ramp) and frequency drift (parabolic phase ramp). In a little more complex model, you compensate for the temperature dependence. In an even more complex model, you compensate for the aging process, the magnetic field etc. Cheers, Magnus _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts