Signal processing apparatus and method

A physiological monitor comprising:

• a first input configured to receive a first signal M.sub.1 having a primary portion, S.sub.1, and a secondary portion N.sub.1, said signal M.sub.1 related to a physiologic parameter;
• a second input configured to receive a second signal M.sub.2 having a primary portion S.sub.2 and a secondary portion N.sub.2, said first and said second signals M.sub.1 and M.sub.2 being in accordance with the following relationship:
• M.sub.1 =S.sub.1 +N.sub.1
• M.sub.2 =S.sub.2 +N.sub.2
• where S.sub.1 and S.sub.2, and N.sub.1 and N.sub.2, are related by:
• S.sub.1 .apprxeq.r.sub.a S.sub.2
• N.sub.1 .apprxeq.r.sub.v N.sub.2
• and where r.sub.a and r.sub.v are coefficients;
• a first signal processor, said first signal processor configured to compute said r.sub.a coefficient and said r.sub.v coefficient using a transformed representation of said first signal M.sub.1 and a transformed representation of said second signal M.sub.2 ;
• and
• a waveform scrubber having a first input configured to receive said first signal M.sub.1, and having a second input configured to receive said second signal M.sub.2, said waveform scrubber providing an output signal corresponding to an approximation of S.sub.1.

In a signal processor for processing at least two measured signals M.sub.1 and M.sub.2, the signal M.sub.1 having a primary signal portion S.sub.1 and a secondary signal portion N.sub.1, the signal M.sub.2 having a primary signal portion S.sub.2 and a secondary signal portion N.sub.2, such that:

• M.sub.1 =S.sub.1 +N.sub.1
• M.sub.2 =S.sub.2 +N.sub.2
• where S.sub.1 and S.sub.2, and N.sub.1 and N.sub.2, are related by:
• S.sub.1 .apprxeq.r.sub.a S.sub.2
• N.sub.1 .apprxeq.r.sub.v N.sub.2
• and where r.sub.a and r.sub.v are coefficients, a method comprising the steps of:
• determining a value for a coefficient c, such that an error value e, given by the relation e=S.sub.1 -(cM.sub.1 -M.sub.2) is partially minimized;
• and
• using said coefficient c in a waveform scrubber to remove some of the signal N.sub.1 from the measured signal M.sub.1 to produce an approximation A.sub.1 to said signal S.sub.1, where A.sub.1 =cM.sub.1 -M.sub.2, and where A.sub.1, M.sub.1, and M.sub.2 are expressed as frequency domain signals.

A physiological monitor comprising:

• a first input configured to receive a first measured signal M.sub.1 having a primary portion, S.sub.1, and a secondary portion N.sub.1 ;
• a second input configured to receive a second measured signal M.sub.2 having a primary portion S.sub.2 and a secondary portion N.sub.2, said first and said second measured signals M.sub.1 and M.sub.2 being in accordance with the following relationship:
• M.sub.1 =S.sub.1 +N.sub.1
• M.sub.2 =S.sub.2 +N.sub.2
• where S.sub.1 and S.sub.2, and N.sub.1 and N.sub.2, are related by:
• S.sub.1 .apprxeq.r.sub.a S.sub.2
• N.sub.1 .apprxeq.r.sub.v N.sub.2
• and where r.sub.a and r.sub.v are coefficients;
• a first signal processor comprising a neural network configured to compute said r.sub.a coefficient and said r.sub.v coefficient using a transformed representation of said signal M.sub.1 and a transformed representation of said signal M.sub.2 ;
• and
• a waveform scrubber having a first input configured to receive said first measured signal and having a second input configured to receive said second measured signal, said waveform scrubber providing an output corresponding to an approximation of S.sub.1.