US 6,639,957 B2 · Method and system for calibrating an oscillator circuit using a network based time reference

Abstract

A method and system of compensating for reference frequency drift utilizes time stamps from a networked reference clock to adjust a local crystal oscillator of a communications device. In an example embodiment, a microprocessor arrangement of the communications device obtains a synchronization time stamp from a networked clock arrangement and synchronizes the local oscillator clock and a clock circuit of the microprocessor with the time stamp. After a predetermined time duration has transpired, a calibration time stamp is obtained from the network clock and the difference between the calibration time stamp and the current time of the clock circuit is extracted. The clock circuit and the networked clock arrangement are then synchronized and the local crystal oscillator is adjusted for crystal aging as a function of the difference between the calibration time stamp and the current time of the clock circuit.

Claims22

Dependent claims

A method of compensating for reference frequency drift in a communications device, the communications device having a microprocessor arrangement and a local oscillator circuit adapted to generate a reference frequency signal and operate synchronously with a clock circuit of the microprocessor arrangement, the method comprising:

a) generating a clock circuit time reference for the clock circuit by dividing the reference frequency signal by a divisor;
b) obtaining a synchronization time stamp from a networked reference clock arrangement operably connected to the microprocessor arrangement and synchronizing the clock circuit to the synchronization time stamp;
c) obtaining a calibration time stamp from the networked reference clock arrangement after a predetermined time duration has transpired from synchronization of the clock circuit and comparing the calibration time stamp to a current time of the clock circuit;
and
d) synchronizing the current time of the clock circuit with the calibration time stamp and adjusting the local oscillator circuit as a function of a time variation between the calibration time stamp and the current time of the clock circuit.

2 more elements

A system for compensating for reference frequency drift in a communications device, the communications device having a microprocessor arrangement and a local oscillator circuit adapted to generate a reference frequency signal and operate synchronously with a clock circuit of the microprocessor arrangement, the system comprising:

a) means for generating a clock circuit time reference for the clock circuit by dividing the reference frequency signal by a divisor;
b) means, responsive to generation of the clock circuit time reference, for obtaining a synchronization time stamp from a networked reference clock arrangement operably connected to the microprocessor arrangement and for synchronizing the clock circuit to the synchronization time stamp;
c) means, responsive to a predetermined time duration transpiring from synchronization of the clock circuit, for obtaining a calibration time stamp from the networked reference clock arrangement and comparing the calibration time stamp to a current time of the clock circuit;
and
d) means, responsive to the calibration time stamp comparison, for synchronizing the current time of the clock circuit with the calibration time stamp and adjusting the local oscillator circuit as a function of a time variation between the calibration time stamp and the current time of the clock circuit.

2 more elements

A reference frequency compensation circuit arrangement having a local crystal oscillator circuit adapted to generate a reference frequency signal, the frequency compensation circuit arrangement comprising:

a dividing circuit adapted to divide the reference frequency signal so as to generate a clock circuit time reference;
and
a microprocessor arrangement operably connected to a networked reference clock arrangement and having a clock circuit, the microprocessor arrangement adapted to obtain a synchronization time stamp from the networked reference clock arrangement and synchronize the clock circuit time reference to the synchronization time stamp, the microprocessor arrangement also adapted to obtain a calibration time stamp from the networked reference clock arrangement after a predetermined time duration from the synchronization of the clock circuit has transpired and adapted to compare the calibration time stamp to a current time of the clock circuit, the microprocessor arrangement further adapted to synchronize the current time of the clock circuit with the calibration time stamp and adjust the local oscillator circuit as a function of a time variation between the calibration time stamp and the current time of the clock circuit.

Dependencies are inferred from the claim text.

Method and system for calibrating an oscillator circuit using a network based time reference

Life of this patent

Method and system for calibrating an oscillator circuit using a network based time reference

Life of this patent

Abstract

Claims22