Apparatus and method for synchronizing a communication system
 Apparatus and method for synchronizing a local clock signal with a remote clock signal. The local clock signal is divided by a digital counter for generating a phase increment signal. The phase increment signal and the remote clock signal are applied to a further digital counter for counting the number of phase increment signal cycles received during a predetermined number of cycles of the received remote clock signal and generating a count value in response thereto. A microprocessor performs a table look-up for retrieving a predetermined digital correction value using an address characterized by the count value. The correction value is applied to a digital-to-analog converter for generating an analog control voltage in response thereto. The analog control voltage is applied to a master voltage control oscillator for generating the local oscillator signal such that the local oscillator signal frequency is adjusted to be synchronized with the remote clock signal in both phase and frequency. The apparatus comprises low cost circuitry and consumes very little circuit board area and power. 
Mitel Corporation
H H
H03L H04L
inventional inventional
A. David Scott Thanh
Milton Marshall Tran