Patent ID: 6130602
Filing Date: 2000-10-10
Classification: G06K,H01Q,H03L

Abstract:
A method for conserving power in a radio frequency identification device defined by a single integrated circuit including a microprocessor and receiver, the method comprising in the single integrated circuit periodically switching from a sleep mode to a receiver-on mode and performing the following tests to determine whether to further switch to a microprocessor-on mode, in which more power is consumed than in the receiver-on mode, because a valid radio frequency signal is present:(a) determining if any radio frequency signal is present and, if so, proceeding to step (b); and, if not, returning to the sleep mode;(b) determining if the radio frequency signal is modulated and has a predetermined number of transitions per a predetermined period of time and, if so, proceeding to step (c); and, if not, returning to the sleep mode; and(c) determining if the modulated radio frequency signal has a predetermined number of transitions per a predetermined period of time different from the predetermined time of step (b) and, if so, switching from the receiver-on mode to the microprocessor on mode; and, if not, returning to the sleep mode.