At&t Ipm Corp.

At+t Corp.

Herbert W Tam

A cordless telephone arranged for operation in a frequency hopping system quickly establishes communications between a base unit and an associated handset unit in the telephone. Synchronization between the base unit and the handset unit is achieved through a process in which first the base unit sends a start hopping message contiguously for a specific number of frames or time slots. The handset unit, in turn, responds by sending a staff hopping acknowledge message to the base unit in a frame each time it receives the start hopping message in a frame. In response to the handset unit sending the start hopping acknowledge message, the base unit sends to the handset unit an acknowledge hopping message, also for a specific number of frames. If either the base unit or handset unit fails to receive a message in a specific frame, the synchronization process advantageously continues since each one of the messages contained in the specific number of frames linearly decreases in value with each succeeding frame. Both the base unit and handset unit are thus able to predict the value for each message not received in one or more specific frames. Upon receipt of the acknowledge hopping message by the handset unit from the base unit in at least one frame, therefore, both the base unit and the handset unit are synchronized and will begin frequency hopping when the value for this message linearly decreases in time to a predetermined value. Should ongoing communications between the base unit and the handset unit be inadvertently interrupted, the cordless telephone quickly reestablishes communications in the frequency hopping system through this same synchronization process.

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Edison, NJ, United States of America

Herbert W Tam