| 摘要 |
A device for eliminating ringings in filtered ECG-signals comprises an A/D-converter (10) for converting analog input signals into a series of digital values and a filter unit (14, 16) connected to the output of the A/D-converter. The filter unit comprises a recursive IIR-filter (14) and a subsequent allpass-filter (16) with a phase shift which is equal to twice the phase shift of the IIR-filter. The allpass-filtration is performed time-reversed in relation to the IIR-filtration. In a method for producing an allpass-filter (16) with a phase shift which is equal to twice the phase shift of an IIR-filter (14) the zero points of which are situated on the unity circle in the Z-plane, which allpass-filter is suitable for use in the device according to the invention, the zero points of the IIR-filter are replaced by new zero points obtained by reflecting the poles of the filter in the unity circle in the Z-plane. <IMAGE> |
