Clock receiver for network synchronization control of exchange system

DETAILED DESCRIPTION Therefore, it is an object of the present invention to provide an improved network synchronization control.
It is another object to provide a clock receiving process and circuit for accommodating both trunk clock signals and digital office time supply clock signals.
It is another object to provide a clock receiving circuit for enabling compatibility between conventional networks.
It is still another object to provide a clock receiving process circuit for enabling network synchronization control of an exchange system.
To achieve these and other objects, the present invention provides a clock receiving process and circuit for network synchronization control of an exchange system.
The clock receiving circuit includes a clock receiving unit for receiving a predetermined number of network synchronization reference clock signals exhibiting differential voltage levels from a trunk or a digital office time supply, and providing output of the network synchronization reference clock signals in corresponding logic levels.
A clock determination unit determines whether the network synchronization reference clock signals received in the clock receiving unit are from the trunk or the digital office time supply.