https://www.microchip.com/missionassu...

They say “timing is everything” and the piezoelectricity of crystalline quartz, coupled with a positive feedback oscillator, provides a reference clock for that “everything” from FPGAs to deep space satellites.

Let us show you how heaters with thermistors or varactors with ASICs are used to stabilize the frequency to less than a part per billion over wide temperature ranges, radiation environments or crazy shock and vibration conditions.