Structure-borne sound detector for break-in surveillance
US5705985A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 13, 1996 |
| Grant date | Jan 6, 1998 |
| Priority date | — |
| Expiry date | Feb 13, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S367/901
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A structure-bone sound detector suppresses unwanted signals in a frequency range to be monitored, to enhance the immunity of the detector to false alarms. The output signal from a sound sensor undergoes preprocessing, and is then fed to a pair of comb filters that are connected in parallel. The comb filters have mirror image filtering characteristics. The filtered output signals from the two comb filters are provided to a minimum value stage, which selects the smaller of the two output signals. This selected signal is further processed to detect an alarm condition. With this arrangement, broad band signals of interest will produce approximately the same outputs from each of the two comb filters, and therefore be passed on for further processing. In contrast, a narrow band interference signal will be suppressed by one of the two comb filters, and therefore not selected for further processing.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.