A noise cancelling filter for the digital Holter monitoring system

We are developing a complete digital Holter monitoring system (HMS). One important problem required with the digital HMS is the ability of huge data storage and processing. A conventional HMS uses an analog magnetic tape to record long-time data. Although recoding the huge data into a magnetic tape is the easiest way, it is not suitable for realizing a simple compact digital HMS. Our main objective is to realize a simple digital HMS. Therefore we have to recode the huge electrocardiogram (ECG) data into a semiconductor memory (IC memory card) instead of the magnetic tape. In order to record the long-time ECG signal into an IC memory card, it has to be compressed with a high ratio over 1/50. A noisy ECG signal with very low fluctuations cannot be compressed sufficiently. A noise cancelling method which is effective for the data compression, is proposed