Tai S C
Institute of Electrical Engineering, National Cheng-Kung University, Tainan, Taiwan, Republic of China.
Med Biol Eng Comput. 1992 Mar;30(2):187-92. doi: 10.1007/BF02446129.
An ECG sampled at a rate of 500 samples s-1 or more produces a large amount of redundant data that are difficult to store and transmit. A process is therefore required to represent the signals with clinically acceptable fidelity and with the least code bits possible. In the paper, an efficient sub-band coding method for encoding ECG waveforms is presented. Although sub-band coding has been successfully applied to speech signals, it is the first time that this technique has been applied to the encoding of ECG waveforms. A frequency band decomposition of an ECG waveform is carried out by means of quadrature mirror filters (QMF), which split the ECG spectrum into six bands of unequal width. In the lower frequency bands, which contain most of the ECG spectrum energy, a larger number of bits per sample is used, whereas in upper frequency bands, which contain noise-like signals, fewer bits per sample and the run length coding method are used. The simulation results are presented in terms of bit rates and the quality of the reconstructed waveforms. The results show that a reproduction with an average signal-to-noise ratio (SNR) of 29.97 dB can be achieved even at an average bit rate of 0.81 bits per sample.
以500样本/秒或更高的速率采样的心电图会产生大量难以存储和传输的冗余数据。因此，需要一种方法来以临床可接受的保真度且用尽可能少的编码比特来表示这些信号。本文提出了一种用于编码心电图波形的高效子带编码方法。尽管子带编码已成功应用于语音信号，但这是该技术首次应用于心电图波形的编码。通过正交镜像滤波器（QMF）对心电图波形进行频带分解，该滤波器将心电图频谱分成六个宽度不等的频段。在包含大部分心电图频谱能量的低频段，每个样本使用较多的比特数，而在包含类噪声信号的高频段，每个样本使用较少的比特数并采用游程编码方法。仿真结果以比特率和重建波形的质量来呈现。结果表明，即使平均比特率为每个样本0.81比特，也能实现平均信噪比（SNR）为29.97 dB的再现。
