MicroSet may be ordered with a Temperature Compensated Crystal Oscillator (TCXO). This special oscillator significantly improves the accuracy of MicroSet readings when you are concerned about very high accuracy or temperature effects.
The standard timebase in MicroSet is a 16 MHz crystal oscillator that is carefully adjusted to an error of +/- one part per million. This high accuracy is accomplished by hand matching each crystal to the other components in the circuit, and then fine tuning the rate with an adjustable capacitor. Finally, there is also a software correction algorithm that can apply a "trim" value to zero out any remaining error or any drift that accumulates over time. However, a standard quartz crystal will change its rate in small ways as the temperature changes. My experiments have shown that a change of 15 degrees Farenheit over several hours might cause a three or four part per million change in MicroSet's timekeeping accuracy. This can be a problem if the subject of your study is the temperature response of a precision pendulum.
The optional TCXO timebase for MicroSet will eliminate this change in timekeeping accuracy over room temperature ranges. Our experiments have shown the rate to be accurate to one part per million over a range of 40 to 110 degrees Farenheit. These measurements were made by capturing the one second output of a rubidium reference oscillator while the temperature of the exposed MicroSet circuit board was cooled with ice packs and heated with electric coils. The reading of 1.000000 seconds did not change.