Lux, James P skrev: > > > On 11/28/08 11:27 AM, "Bill Hawkins" <[EMAIL PROTECTED]> wrote: >> Has any work been done on temperature compensation of quartz or other >> oscillators to avoid the expense, space, and power of ovens? The >> oscillating material must have a repeatable temperature curve, of >> course. > Look at MCXOs, a very clever technique using the different between third > overtone and fundamental to measure the temperature of the rock.
The fundamental and third overtones have different temperature dependencies. The difference is essentially linear, so by dividing the third overtone down by three or tripping the base frequency and then compare them in a mixer to get the beat frequency and count that, adjustment to the frequency can be performed, often through a DDS clocked at the third overtone. The traditional suppression of major resonances becomes slightly different in the oscillator core, since now both the fundamental and third overtones is wanted. It is however not a big mystery. You could use this temperature sensing technique to with an OCXO solution to let the inner oven be sensed in the crystal. A combined solution would both feed forward and feed backwards. The MCXO and many others is very well presented in the big presentation that John Vig has (http://www.ieee-uffc.org/freqcontrol/tutorials/vig3/vig3.ppt). In general, there is plentifull of good information to read at: http://www.ieee-uffc.org/fcmain.asp?view=review#tutor Reading through that and parts of the NIST T&F archive should elivate your knowledge pretty fast and it is all for free. Just costs you the time to read. Cheers, Magnus _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
