ECG signal compression using ASCII character encoding and transmission via SMS

• R-peak detection by differentiation and squaring technique.
• Lossless compression in QRS regions and lossy compression in non-QRS regions.
• Compressed file contains only 8-bit ASCII characters (CR = 22.34).
• 8-bit to 7-bit conversion of ASCII characters for transmission via SMS.
• ECG signal reconstruction at receiving/doctor's end.

Software based efficient and reliable ECG data compression and transmission scheme is proposed here. The algorithm has been applied to various ECG data of all the 12 leads taken from PTB diagnostic ECG database (PTB-DB). First of all, R-peaks are detected by differentiation and squaring technique and QRS regions are located. To achieve a strict lossless compression in the QRS regions and a tolerable lossy compression in rest of the signal, two different compression algorithms have used. The whole compression scheme is such that the compressed file contains only ASCII characters. These characters are transmitted using internet based Short Message Service (SMS) and at the receiving end, original ECG signal is brought back using just the reverse logic of compression. It is observed that the proposed algorithm can reduce the file size significantly (compression ratio: 22.47) preserving ECG signal morphology.

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