Abstract: Apparatus and method are disclosed for deriving the maximum and minimum peaks of a wave representing blood pressure by comparing it with offsets that may be arbitrarily set or derived from the blood pressure signal, which offsets are alternatively added to and subtracted from the approximate mean of the blood pressure signal.

Abstract: Signals having desired peaks and undesired peaks that may be due to noise are processed so as to identify the desired peaks by determining a first difference between the amplitude of every peak and a long-term average of the peak amplitudes and then obtaining a second difference between the first difference and the average of such first differences. If the second difference exceeds a predetermined amount, the peak is considered to be undesired; but if the second difference is less than the predetermined amount, the peak is considered to be desired. If the desirable peaks represent systolic or diastolic blood pressures, their respective averages are considered to be unreliable if the number of desired peaks occurring within a given time is less than an arbitrarily selected number; and if the ratio of undesirable to desirable peaks is less than a predetermined amount, the signal is considered to be of poor quality so that the averages attained are suspect.

Abstract: Apparatus for deriving an average of data points in which the contribution of each data point to the average is generally inversely related to the difference between its amplitude and the amplitudes of a few previous data points.