Abstract: A method and apparatus for detecting P or T waves in an electrocardiogram signal in intervals before and after each (previously) detected QRS wave. Within each interval, a candidate pair of samples are selected. If the candidate pair are separated by a time duration which does not exceed a predefined time duration then that pair is rejected and the process repeats. Otherwise, the area "A" of a closed polygon bounded by all of the samples between and including the candidate pair is derived (the polygon's base line extends linearly a distance "d" between the candidate pair of sample intervals). The maximum vertical displacement "h" between the base line and any portion of the polygon above the base line is derived. If "h" does not exceed a predefined minimum vertical displacement, then the candidate pair is rejected and the process repeats. Otherwise, a value Gamma=A*h/d is derived for the candidate pair.

Abstract: An apparatus and method for compressing an input sequence of data items produced by sampling a periodic waveform compresses such input sequence by searching a history buffer operable to store consecutive data items, to locate a stored sequence of consecutive data items matching the input sequence. Matching is deemed to occur when each data item in the input sequence is within non-equal upper and lower limits of its corresponding data item in the stored sequence. When a stored sequence matching the input sequence is located compressed output data is produced to represent the stored sequence and the stored sequence is again stored in the history buffer to succeed the data items already stored therein. When a stored sequence matching the input sequence is not located, a representation of the first data item in the input sequence is produced and the first data item is stored in the history buffer to succeed the data items already stored therein.