Circuit system and method for receiving and demodulating signals to a tire pressure monitoring system. The circuit comprises a demodulator for receiving an input signal modulated at a first frequency and demodulating the input signal so that information can be extracted from the input signal at a second frequency lower than the first frequency. The circuit further comprises a microprocessor, operating at a clock rate selected to extract information from the demodulated signal at the second frequency, for receiving and decoding a demodulated signal from the demodulator. In another aspect, the demodulator comprises a switching circuit having a time constant longer than the period of the first frequency. The switching circuit provides a low signal when the demodulator receives an input signal in a first state, remains low after the amplified signal changes to a second state for a time constant period, and provides a high signal when the amplified signal is in the second state after the time constant period has elapsed.
