Intrusion detection systems with turbulence discrimination
US4003045A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 1, 1975 |
| Grant date | Jan 11, 1977 |
| Priority date | — |
| Expiry date | Oct 1, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B13/1627
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An intrusion alarm system employs ultrasonic frequencies and operates in the presence of turbulence. The system includes a differentiator and an integrator, each coupled to a sample and hold circuit; the differentiated pulses determining the level from the integrator, which level is stored in the sample and hold circuit during a predetermined time interval. The level, as stored, will be relatively constant for the presence of an intruder and will exhibit excursions during turbulence. A threshold circuit is responsive to the steady level during a predetermined period to sound an alarm determinative of an intrusion. During turbulence, the signal stored fluctuates and is discriminated against by the threshold circuit to assure that the alarm will not occur for this condition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.