Alarm sensor and antenna arrangement
US5999090A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 13, 1998 |
| Grant date | Dec 7, 1999 |
| Priority date | — |
| Expiry date | Jan 13, 2018 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB60R25/1009
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A microwave frequency Doppler vehicle intruder alarm comprises an oscillator 3, a mixer 2 and an amplification stage 4, 5 having its output applied to a low-pass filter 7, whose output is split into two branches. A first branch, comprising a rectifier diode and a comparator, provides a signal on its output when a significant level of non-carrier microwave signals is received. This branch is sensitive to signals having Doppler frequencies of 0-200 Hz, which includes the intruder indicative frequencies. A second branch, comprising an amplifier 8, a high pass filter 9, and a comparator 10, provides an output signal on the detection of a significant level of signals in the 40-200 Hz band, which frequencies are indicative of externally generated interference. A logic element 15 mutes the output of the alarm when the second branch indicates the presence of externally generated interference. An antenna arrangement (FIG. 3, not shown) generates a rectangular radiation field which provides optimum coverage of the interior of a vehicle by being mounted in the roof thereof. Steering of the radiation field to provide optimum illumination when the arrangement is mounted off-center on the roof i…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.