lists at rtty.us
Thu Aug 30 16:33:59 UTC 2012
The fundamental / third approach is one of several possible ways to go. You
can also run an SC on the B and C modes to get thermometer data. Early
implementations used a pair of independent blanks, one cut to be a good
thermometer. Some have even gone as far as to mount a thermistor on the
No matter what you do, it adds cost.
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Jim Lux
Sent: Thursday, August 30, 2012 8:55 AM
To: time-nuts at febo.com
Subject: Re: [time-nuts] oscillators
On 8/29/12 8:45 PM, Richard (Rick) Karlquist wrote:
> On 8/27/2012 11:45 PM, WB6BNQ wrote:
>> A microprocessor controlled XO is a non oven crystal oscillator system
>> that has
>> additional computational control providing a bit more than just mere
>> temperature compensation. The additional computational capability
>> deals with
>> having coefficients of that particular oscillator's behavior pre coded to
>> compensate for the nonlinear behavior over a given temperature rang
> It doesn't use coefficients. It has a look up table of frequency vs
>> A microprocessor controlled XO system allows for using cheap crystals
>> minimum processing time and costs. Because of limited storage space
>> there is no
> No it doesn't use a cheap crystal. It uses a *special* SC cut crystal.
> This crystal could very easily cost more than an OCXO crystal.
Isn't the crystal cut (and the circuit designed) in such a way that it
supports both the fundamental and the third overtone simultaneously, and
comparing the frequencies of the two (or, more accurately, fF- fthird/3)
is how they measure the temperature, which is then used to look up the
correction factor in a PROM.
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
and follow the instructions there.
More information about the Time-nuts_lists.febo.com