Patent ID: 7545887

Claim:
A synchronous detection method, performed in a synchronous detection device, of detecting a target carrier wave from an input signal containing the target carrier wave, the target carrier wave periodically oscillating positively and negatively in time according to a constant frequency and a period, the method comprising: inputting, in a synchronous detection device, an input signal containing the target carrier wave; averaging, in the synchronous detection device, the input signal over at least first and second phase ranges of the target carrier wave within each period thereof to obtain at least first and second moving average values of the input signal within the at least first and second phase ranges, respectively, the first phase range corresponding to a phase range within which the target carrier wave positively oscillates, the second phase range corresponding to a phase range within which the target earner wave negatively oscillates; and calculating, in the synchronous detection device, a difference between the first and second moving averages, to produce as an output signal, a detection result of the target carrier wave.