Communications: directive radio wave systems and devices (e.g. – Directive – Position indicating
Patent
1994-01-31
1997-08-26
Tarcza, Thomas H.
Communications: directive radio wave systems and devices (e.g.,
Directive
Position indicating
342457, 342463, 340502, G01S 302
Patent
active
056614926
ABSTRACT:
A population of locatable personal detection units (PDUs) (20) are worn by users. Any number of locators (14) are placed at known locations within an area (10) where the users tend to be. When an alarm event for an individual user occurs, a request signal is transmitted from the user's PDU (20). The request signal is received at several of the locators (14), each of which measure the power level of the request signal. A central computer (16) selects some of these locators (14) in response to the power level measurements. In sequence, the selected locators (14) transmit an interrogation signal to the PDU (20), the PDU (20) replies to the interrogation signal, and the locators (14) measure the duration transpiring between the interrogation and the reply. Based on the durations measured for at least three of the locators, the central computer (16) uses a multilateration process to localize the PDU (20).
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An article entitled "Implementation of GEOSTAR.RTM. RDSS Spectrum Receiver" by Masoud Motamedi & Robert D. Briskman from Geostar Corporation, IEEE, 1987.
Baumann William John
Shoap Stephen Davis
Fliegel Frederick M.
Motorola Inc.
Phan Dao L.
Tarcza Thomas H.
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