Noise cancelling for the digital holter monitoring system

Abstract

The present trend is to develop a totally digital Holter electrocardiogram (ECG) recording system. To this end, research and development are in progress for the digital Holter ECG as the recorder. The conventional Holter ECG is a device which is carried for long hours and records the ECG waveforms on magnetic tape as the analog signal. It has problems in accuracy, e.g., waveform distortion, moving parts such as the motor, as well as volume and weight. The digital Holter ECG considered in this paper is the simplified digital Holter ECG which converts ECG waveforms for 24 hours into digital form, to record and process various waveforms. By totally designing the system in a digital form, the circuit can easily be integrated into LSI. By using the IC memory card as the recording medium, a small-sized and lightweight equipment can be realized. Thus, the problems in the past system can be solved. A problem in the present IC memory card is that the recording capacity is limited; and the data compression of approximately 1/60 is required to record ECG waveforms for 24 hours. The achievable compression ratio is affected by the noise on the ECG waveform and the fluctuation of the baseline. This study is concerned with the method to eliminate the noise, which is a problem in the data compression. The results of analysis and simulation are presented.