A time tagging circuit which time tags the incoming 1pps with a resolution of 200ps, and an inherent jitter of < 1ns rms. The internal clock analogue interpolator is self calibrating.
An interface to the GPS receiver decodes messages and extracts relevant information, such as time correction data for the 1pps output.
A 1pps output which has the short term stability of the rubidium/ OCXO ( jitter <100ps RMS).
This output may be steered into time coincidence with GPS time/UTC. Steering resolution is 1ns.
Holdover mode is initiated by failure of the 1pps input, or by reception of appropriate data from the GPS receiver that indicates that the 1pps is inaccurate. During holdover measured values of frequency offset and drift is used to steer the oscillator. The output 1pps will still be available.
A comprehensive computer interface that can be used to monitor the progress of the Kalman filter, and to set parameters for the type of oscillator to be controlled. communication with the GPS receiver is possible through the single interface. Operating parameters are stored in non volatile memory.