Supervised wireless security system
US4367458A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 29, 1980 |
| Grant date | Jan 4, 1983 |
| Priority date | — |
| Expiry date | Aug 29, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B11/00
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An ultrasonic communication system capable of wireless installation and supervised operation is achieved by communicating each information bit as two distinct ultrasonic frequencies separated in frequency enough to assure that the signal strength of both transmissions will not be in a deep null at the receiver location at the same time. The transmissions can be coded with a format that recognizes the correct data transmission even if reception of one frequency is lost. By use of transponders and other auxiliary units with periodic polling, supervised operation throughout a building can be maintained with events such as intrusion, fire or emergency as well as failures of particular units of the system reported.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.