Methods and apparatus for detecting electromagnetic interference
US6700388B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 19, 2002 |
| Grant date | Mar 2, 2004 |
| Priority date | — |
| Expiry date | Jul 1, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/001
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An EMI testing scheme involves analyzing an analog input signal in frequency band segments. The input signal is passband filtered and digitally sampled before being converted to a complex analytic signal via a Hilbert transform filter and then transformed into a frequency domain signal via a Discrete Fourier Transform (DFT). Pre-stored frequency window filters are then applied to the frequency domain signal. The set of discrete filter sample points which form the window filters are designed such that particular frequency sub-bands of a desired bandwidth within the frequency segment are selected for EMI analysis. By applying different frequency window filters to the frequency domain signal, different frequency sub-bands are sequentially selected for analysis. An inverse DFT transforms the filtered signal back to the time domain, and the peak voltage of the time domain signal is compared with a threshold to determine whether EMI levels within the selected sub-band are acceptable.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.