Classified Vector Quantization Of Multi-beat M-aztec Coded ECG
C.P. Mammen, Bhaskar Ramamurthi · 2005
We propose a scheme based on Vector Quantization (VQ) for the data-compression of multichannel ECG waveforms. Multichannel ECG is first coded using m-AZTEC, a multichannel extension of the AZTEC algorithm. As in AZTEC, the waveform is approximated using only lines and slopes; however, in m-AZTEC, the N channels are coded simultaneously into a sequence of N+l dimensional vectors, thus exploiting the correlation that exists across channels in the AZTEC durationparameter. We then form multi-beat m-AZTEC vectors, taking pairs vectors which are equidistant from the QRS complex on adjacent beats. The multi-beat m-AZTEC vectors thus formed have twice the dimensionality of the original m-AZTEC vectors. By applying Classified Vector Quantization (CVQ) to these multi-beat m-AZTEC vectors, we exploit the correlation that exists, in the AZTEC value-parameter, across channels as well as between beats, and achieve substantial compression. The final output differs little from the AZTEC output and hence ought to enjoy the same acceptability.