Apparatus and method for sensing a rearward facing child seat with error detection

摘要

An apparatus (52) senses the presence of a rearward facing child restraint seat (34) in a vehicle. Signal generating components (80, 84 and 90) of a driver/receiver circuit (64) provide an electrical transmit signal, at a first frequency, which is applied to an antenna (60) and the antenna transmits an electromagnetic (EM) signal (62) at the first frequency during a first time period. During a second time period, a component (84) of the driver/receiver circuit (64) provides a signal at a second, different frequency. An identification tag (54) is securable to the child restraint seat (34) and provides an EM return signal (68) in response to the EM transmit signal (62). The antenna (60) receives the EM return signal (68) and provides an electrical return signal in response to the EM return signal. A mixer (122) is coupled to receive both the second frequency signal and the electrical return signal in the second time period, and provides a beat frequency signal. The presence and duration of the beat frequency signal may be indicative of the presence of the identification tag (54). An output signal from the driver/receiver circuit (64) is a function of the beat frequency signal and contains information. A processor (70) processes the information in the output signal and determines: (i) presence of the identification tag (54) and (ii) whether the information is unreliable thus affecting the determination of presence of the identification tag.