Indirectly sensed signal processing in active periodic acoustic noise cancellation
US5502770A · kind A · utility
14Cited by
27References
17Claims
0Family size
Assignee
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Key dates
| Filing date | Nov 29, 1993 |
| Grant date | Mar 26, 1996 |
| Priority date | — |
| Expiry date | Nov 29, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10K2210/3045
- WIPO fieldOther consumer goods
- WIPO sectorOther fields
Abstract
The system employing and the processing of, an indirectly sensed signal representative of a periodic noise acoustic wave into an input signal for a noise cancelling system where the indirectly sensed signal is converted into a pulse signal per period that carries fundamental and harmonic frequency information of the periodic noise. A tachometer type RPM signal is processed in a counter circuit controlled by a logic circuit to produce a signal of one pulse per revolution with a controlled duration, the pulse amplitude is adjusted, the pulses are low pass filtered and any D.C. is blocked from the noise cancelling system input.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.