Auxiliary precision timekeeper for GPS receiver

A computer program product including one or more non-transitory machine-readable mediums encoded with instructions that when executed by one or more processors cause a process to be carried out for global positioning system (GPS) receiver timekeeping, the process comprising:

• generating a system clock signal at a reference frequency, the system clock signal having a first frequency stability;
• generating an auxiliary clock signal at an auxiliary clock frequency, the auxiliary clock signal having a second frequency stability that is greater than the first frequency stability, wherein the auxiliary clock frequency differs from the reference frequency by a frequency offset;
• calculating corrections to the auxiliary clock signal based on a measure of error in the frequency offset and on an estimate of error in the auxiliary clock frequency;
• and
• using the calculated corrections to generate a timing signal, during times when less than four GPS satellite signals are received.

A method for global positioning system (GPS) receiver timekeeping, the method comprising:

• generating, by a processor-based system, a system clock signal at a reference frequency, the system clock signal having a first frequency stability;
• generating, by the processor-based system, an auxiliary clock signal at an auxiliary clock frequency, the auxiliary clock signal having a second frequency stability that is greater than the first frequency stability, wherein the auxiliary clock frequency differs from the reference frequency by a frequency offset;
• calculating, by the processor-based system, corrections to the auxiliary clock signal based on a measure of error in the frequency offset and on an estimate of error in the auxiliary clock frequency;
• and
• using the calculated corrections to generate a timing signal, during times when less than four GPS satellite signals are received.