System for tracking an article or person
US5708421A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 19, 1996 |
| Grant date | Jan 13, 1998 |
| Priority date | — |
| Expiry date | Aug 19, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B21/0202
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A system for tracking articles or persons comprising a base unit for transmitting a series of ultrasonic signals and an alarm signal, a remote unit, removably attached to the article or person, for receiving the series of ultrasonic signals from the base unit and for transmitting an electromagnetic signal upon receipt of the ultrasonic signal from the base unit, and a monitoring unit for receiving the alarm signal. The base unit further includes an ultrasonic signal generator, an ultrasonic signal transmitter, an electromagnetic signal receiver for receiving the signal from the remote unit, a timer for determining the amount of time from the transmission of the ultrasonic signals to the receipt of the electromagnetic signal from the remote unit, and a transmitter for transmitting an alarm signal to the remote unit and the monitoring unit when the amount of time from the transmission of the ultrasonic signals to the receipt of the electromagnetic signal from the remote unit is greater than a predetermined amount of time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.