EFFICIENT APPLICATION OF CODING TECHNIQUE FOR DATA-COMPRESSION OF ECG

A technique was developed to reduce ECG data efficiently within a cont rolled accuracy. The sampled and digitized data of the original wavefo rm of an ECG is transformed in three major processes. They are the cal culation of a beat-to-beat variation, a polygonal approximation and th e calculation of the difference between consecutive node points. Then, an adaptive coding technique is applied to minimize redundancies in t he data. It was demonstrated that the ECG waveform sampled in 200 Hz, 10 bit/sample, 5 mu V/digit could be reduced with the bit reduction ra tio of about 10% and within the reconstruction error of about 2.5%. A polygonal approximation method, called MSAPA, was newly developed as a modification of the well known method, SAPA. It was shown that the MS APA gave better reduction efficiency and smaller reconstruction error than the SAPA, when it was applied to the beat-to-beat variation wavef orm. The importance of the low-pass filtering as a preprocessing for t he polygonal approximation was confirmed in concrete examples. The eff iciency of the proposed technique was compared with the cases in which the polygonal approximation was not used. Through these analyses, it was found that the redundancy elimination of the coding technique work ed effectively in the proposed technique.