US 2007/0160089 A1 · Synchronization system using at least one external office line signal and synchronization control method thereof

Abstract

A synchronization system using at least one external office line signal, and a synchronization control method thereof. The synchronization system includes a plurality of framers receiving digital office line signals having a square wave form from a Public Switched Telephone Network (PSTN) through respective line interfaces, converting the digital office line signals into reference clock signals, and a synchronization frequency selector controlling a framer that first generates an interrupt, among the plurality of framers, to provide the corresponding reference clock signal. The synchronization system using at least one external office line facilitates line extension of a digital trunk of a keyphone switching apparatus, stably performs system synchronization by using the reference clock signal as an external synchronization clock to enhances system quality.

Claims10

Dependent claims

A synchronization system using at least one external office line signal, comprising:

a plurality of framers receiving digital office line signals having a square wave form from a Public Switched Telephone Network (PSTN) through line interfaces, converting the digital office line signals into reference clock signals, and simultaneously setting interrupts to “high”;
and
a synchronization frequency selector for controlling the one of said framer that first generates an interrupt among the plurality of framers to provide the corresponding reference clock signal.

A synchronization system control method using at least one external office signal, comprising steps of:

determining whether interrupts are generated from a plurality of framers receiving the digital office line signals;
when the interrupts are generated from the plurality of framers, detecting a framer that first generates an interrupt;
and
providing a first logic control signal having a “high” logic value so that the framer that first generates the interrupt provides the reference clock signal, and simultaneously providing a second logic control signal having a “low” logic value so that the remaining framer cannot provide the reference clock signal.

1 more element

Dependencies are inferred from the claim text.

Synchronization system using at least one external office line signal and synchronization control method thereof

Life of this patent

Synchronization system using at least one external office line signal and synchronization control method thereof

Life of this patent

Abstract

Claims10