Patent ID: 7865222

Claim:
An apparatus for measuring one or more blood constituents in a subject, said apparatus comprising: a first signal source which applies a first input signal during a first time interval in a first modulation scheme; a second signal source which applies a second input signal in a second time interval in a second modulation scheme; a detector which detects a first parametric signal responsive to said first input signal passing through a portion of said subject having blood therein and which detects a second parametric signal responsive to said second input signal passing through said portion of said subject, said detector generating a detector output signal responsive to said first and second parametric signals; and a signal processor which receives said detector output signal, said signal processor demodulating said detector output signal by applying a first demodulation signal to a signal responsive to said detector output signal to generate a first demodulator output signal and applying a second demodulation signal to said signal responsive to said detector output signal to generate a second demodulator output signal, said first demodulation signal having at least one component comprising a frequency, a first amplitude, and a first phase, and said second demodulation signal having at least one component comprising a second frequency, a second phase, and a second amplitude, at least one of said first phase, said second phase, said first amplitude, and said second amplitude chosen to reduce crosstalk from said first parametric signal to said second demodulator output signal and to reduce crosstalk from said second parametric signal to said first demodulator output signal; wherein said signal processor is further configured to adjust at least one of the first and second modulation schemes and adjust a corresponding at least one of said first and second demodulation signals based on the output signals in order to further reduce crosstalk.