Bidirectional filter
US5479922A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 29, 1993 |
| Grant date | Jan 2, 1996 |
| Priority date | — |
| Expiry date | Oct 29, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H17/04
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A system for filtering stochastic signals as embodied in stress test systems for measuring electrocardiographic (ECG) activity in response to exercise employs a bidirectional Infinite Impulse Response (IIR) filtering process over a predetermined window on a digitized version of an ECG signal to eliminate noise up to the 0.67 Hz frequency range. To eliminate phase shifting distortion in the ECG signal, the IIR filter is applied in a first direction over a predetermined window of the ECG and then applied in a second direction opposite the first direction segment over the identical window. In this manner the phase shift distortion normally associated with IIR filters is completely eliminated and superior bandwidth (as compared to FIR filters) is obtained. The response is achieved fast enough to be used in real time purpose.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.