Patent ID: 7522685
Filing Date: 2009-04-21
Classification: G08B,H04L

Abstract:
1. A synchronizing method between a Radio Frequency (RF) transmitter and a battery powered RF receiver wherein: the transmitter transmits first periodic sync signals which are received and used by the receiver to maintain proper synchronization of the receiver with the transmitter during second periodic wake up windows for possible transmissions of data; the transmitter transmits data during at least some of the second periodic wake up windows for the transmission of data; the receiver wakes periodically from a sleep mode to receive the first periodic sync signals which are used by the receiver to maintain the receiver properly synchronized with the transmitter during the second periodic wake up windows for possible transmissions of data from the transmitter; the receiver accurately times a number of consecutive first periodic sync signals received from the transmitter in order to accurately determine the second periodic wake up windows when the receiver comes out of the sleep mode; the receiver wakes periodically for a short duration at the start of each second periodic wake up window to receive a possible transmission of data, and if no transmission is received goes back to the sleep mode, and if a transmission is received stays awake to receive the transmission of data, such that an average current consumed by the battery powered receiver to wake periodically to receive the first periodic sync signals to maintain synchronization and to wake periodically to listen for the possible second periodic transmissions of data is less than the average current required to maintain the receiver awake continuously.