Patent ID: 6721289
Filing Date: 2004-04-13
Classification: G06K,H01Q,H03L

Abstract:
A radio frequency communications device comprising a single integrated circuit including a transmitter and a receiver, the integrated circuit being configured to periodically check if a radio frequency signal is being received by the receiver, the integrated circuit further including a timer configured to set a programmable time period for the checking, the timer being programmable by RF command from a remote interrogator to a user selectable value, selectable in one second increments, the transmitter being configured to use a clock signal having a frequency recovered from the received signal, the integrated circuit being configured to switch between a sleep mode, a receiver-on power mode in which more power is consumed than in the sleep mode and in which the checking takes place, and a microprocessor-on power mode in which more power is consumed than in the receiver-on power mode.