Review and enhancement of ECG data compression and reconstruction method for portable devices

The need to store and transmit ECG signal data is continuously increasing. Due to limited storage capacity and limited transmission bandwidth, there is a need to compress ECG signal. This paper involves review of existing ECG compression methods and enhancements are proposed to simplify them for portable ECG recorder. The portable devices or embedded systems have limited computing/processing power. The enhancements are suggested to reduce complexity of the algorithms to make them compatible for embedded systems. The proposed method is evaluated on the basis of different compression and quality parameters like compression ratio (CR), percent root mean square difference normalized (PRDN) and quality score (QS). The PRDN is an important parameter as it indicates the error introduced. The compression algorithm includes three sequential processing phases: 1. Pre-processing and classification, 2. Linear transformation, 3. Entropy coding. The ECG compression method is analyzed with different quantization factors like 0.5, 1, 2 and 4. The de-compression technique is the inverse process of compression and it reconstructs the original signal with negligible loss of information. Finally, the described method is compared with existing ECG compression algorithms.