Intrusion detection apparatus
US4875198A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 7, 1988 |
| Grant date | Oct 17, 1989 |
| Priority date | — |
| Expiry date | Oct 7, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B29/046
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An intrusion detector and method of operating the detector is disclosed. The detector comprises a means including an antenna for transmitting spaced pulses of radiation energy of a given frequency throughout a region to be protected. Means are also provided for receiving the radiation energy reflected from the protected region. The reflected radiation energy is received between adjacent spaced transmitted pulses in the form of an AC analog signal at the given frequency, the peaks and valleys of which signal vary in amplitude with time. Means are also provided for allocating a portion of the time occurring between transmitted pulses into a plurality of time segments, each of which segments is long enough to correspond to a plurality of cycles of the analog signal. The detector further includes: means for integrating the plural cycles in each of the time segments to arrive at an integral value for each of the time segments; means for converting the integral values into corresponding digital values; means for storing the digital values in memory; means for comparing the stored digital values obtained from the reflected energy from the first transmitted pulse with the corresponding dig…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.