Patent ID: 7003338

Claim:
A method of reducing crosstalk between two signals generated by applying a first pulse and a second pulse to measure a parameter, wherein said first pulse and said second pulse are applied periodically at a first repetition rate defining a period, and wherein said first pulse is generated during a first interval in each period and said second pulse is generated during a second interval in each period, said first and second pulses producing first and second parametric signals responsive to said parameter, said first and second parametric signals being received by a detector which outputs a composite signal responsive to said first and second parametric signals, said method comprising: applying a first demodulation signal to said composite signal to generate a first demodulated output signal, said first demodulation signal comprising at least one component having at least a first amplitude and a first phase; applying a second demodulation signal to said composite signal to generate a second demodulated output signal, said second demodulation signal comprising at least one component having at least a second amplitude and a second phase; lowpass filtering said first demodulated output signal to generate a first recovered output signal responsive to said first parametric signal; lowpass filtering said second demodulated output signal to generate a second recovered output signal responsive to said second parametric signal; and choosing at least one of said first phase, said second phase, said first amplitude, and said second amplitude to reduce crosstalk components in said first recovered output signal and said second recovered output signal based at least in part on data obtained from said detector during a calibration procedure, wherein said choosing comprises: applying said first light pulse during a first time period and measuring said first recovered output during said first time period as a first calibration output and measuring said second recovered output during said first time period as a second calibration output; applying said second light pulse during a second time period and measuring said first recovered output during said first time period as a third calibration output and measuring said second recovered output during said second time period as a fourth calibration output; and computing said first demodulation signal from at least said first calibration output, said second calibration output, said third calibration output, and said fourth calibration output.