Adaptive temperature compensation

Apparatus comprising:

• an oscillator;
• a receiver configured to receive an external reference frequency signal;
• a physical memory;
• a temperature sensor;
• and
• a processing circuit configured:
• to use the external reference frequency signal to derive oscillator compensation data over a range of operating temperatures,
• to store the oscillator compensation data in a first table within the physical memory and, for a given operating temperature, and
• to use the first table to obtain corresponding oscillator compensation data and apply the obtained data to provide compensation for the temperature related frequency drift,
• wherein the processing circuit defines, for the range of operating temperatures, a series of temperature slots each sub-divided into a series of temperature bins, and in that the processor is configured to use an external reference frequency signal to derive oscillator compensation data over the range of operating temperatures by
• a) measuring an operating temperature and using the external reference frequency signal to determine oscillator compensation values for respective temperatures as the operating temperature varies;
• b) accumulating the determined oscillator compensation values in corresponding temperature bins of a second table within the physical memory by adding the determined values to sums in the bins and incrementing counts for the bins;
• and
• c) at spaced intervals in time, using the accumulated values to determine or update the oscillator compensation data stored for one or more slots in the first table.