Sörnmo L
Department of Clinical Physiology, Lund University, Sweden.
Med Biol Eng Comput. 1993 Sep;31(5):503-8. doi: 10.1007/BF02441986.
Time-varying filtering techniques are applied to the problem of baseline correction by letting the cut-off frequency of a linear filter be controlled by the low-frequency properties of the ECG signal. The time-varying filter is implemented as a bank of linear low-pass filters, in which each filter has a slightly differing cut-off frequency. Sampling rate decimation and interpolation are employed because the design of a filter for baseline reduction can be treated as a narrowband filtering problem. All filters have a linear phase response to reduce, for example, ST-segment distortion. The performance of the technique presented is studied on ECG signals with different types of simulated baseline wander. The results are compared with the performance of time-invariant linear filtering and cubic spline interpolation. The results show that an improvement in performance can be achieved when using time-varying filtering, especially at low heart rates or during episodes with excessive base-line wander.
时变滤波技术通过让线性滤波器的截止频率由心电图信号的低频特性控制，应用于基线校正问题。时变滤波器被实现为一组线性低通滤波器，其中每个滤波器具有略有不同的截止频率。采用采样率抽取和插值，因为用于基线降低的滤波器设计可被视为窄带滤波问题。所有滤波器都具有线性相位响应，以减少例如ST段失真。在所提出的技术的性能在具有不同类型模拟基线漂移的心电图信号上进行了研究。结果与时不变线性滤波和三次样条插值的性能进行了比较。结果表明，使用时变滤波可以实现性能的提高，特别是在低心率或基线漂移过大的时段。
