Patent ID: 8237515

Claim:
A method of crystal oscillator control and calibration, comprising: determining temperature gradients between a first temperature sensing circuit and a crystal oscillator for different ambient temperatures, wherein the determined temperature gradients for different ambient temperatures are used as data for future calibration of the crystal oscillator for a particular ambient temperature and a particular internal temperature, wherein the first temperature sensing circuit measures a temperature at the first temperature sensing circuit and a temperature sensing probe measures a temperature at the crystal oscillator, the first temperature sensing circuit and the crystal oscillator being part of a printed circuit board and being disposed in a heat insulating material, the ambient temperatures being measured using a second temperature sensing circuit that is also part of the printed circuit board, but is not disposed in the heat insulating material; storing the determined temperature gradients and associating respective temperature gradients with corresponding ambient temperatures for use for future calibration of the crystal oscillator for the particular ambient temperature and the particular internal temperature; determining, for a first ambient temperature, compensation parameters for the crystal oscillator for different internal temperatures, the internal temperatures being measured using the first temperature sensing circuit inside the heat insulating material, the internal temperatures being provided by a heater disposed inside the heat insulating material, the internal temperatures being higher than the ambient temperatures, a range of internal temperatures being smaller than a range of ambient temperatures.