Personal security system with weighted receiver locations

• US 5,898,367 A
• Filed: 12/11/1996
• Issued: 04/27/1999
• Est. Priority Date: 12/11/1996
• Status: Expired due to Term

• Current Assignee: Detection Systems, Inc. (Robert Bosch GmbH)
• Original Assignee: Detection Systems, Inc. (Robert Bosch GmbH)
• Inventors: Berube, James Edward
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): Pope, Daryl C.
• Application Number:
  US08/763,644
• Time in Patent Office: 867 Days
• Field of Search: 340/505, 340/539, 340/825.36, 340/825.45, 340/573, 455/10, 455/226.2, 455/53.1, 455/49.1
• US Class Current: 340/505
• CPC Class Codes: G08B 25/009 Signalling of the alarm condition to a substation whose identity is signalled to a central station, e.g. relaying alarm signals in order to extend communication range

Abstract

A personal security system uses conversion factors that exaggerate the influence of signal strength to locate transmitting communicators. The system includes an alarm center, portable communicators for transmitting wireless signals and a plurality of fixed receivers in known positions for monitoring the transmissions and detecting the signals. Transmitted information, including signal strength, is forwarded from the receivers to the alarm center. A transmitting communicator is located by the system using the known positions and received signal strength at the detecting receivers. Conversion factors that increase with signal strength magnify its influence, so strong signals dominate the locating calculations. In addition to a calculated location of the transmitting communicator, the alarm center displays the location of a plurality of the detecting receivers, selecting between alternative displayed information depending on a comparison of the received signal strengths.

Claims

1. A personal security system having a portable transmitter manually actuatable to transmit wireless signals and a plurality of receivers in predetermined fixed positions detecting said signals, said system using a weighted average of the detecting receiver positions to locate said transmitter;

characterized in that;

said weighted average includes;

a) the signal strengths received by said respective receivers; and

, b) conversion factors increasing with signal strength, said conversion factors exaggerating the influence of signal strength in the average.

2. A personal security system comprising:

a plurality of portable communicators, each respective communicator having a manual actuator for initiating transmission of wireless signals;

a plurality of receivers fixed in predetermined positions for detecting said transmissions, said detecting receivers communicating information from said signals including received signal strength; and

,

an alarm center receiving said information communicated by said detecting receivers and displaying the respective locations of a plurality of said detecting receivers, said plurality depending on a comparison of said received signal strengths,

wherein said respective locations are displayed as text in alternative formats, and said alternative formats include text pertaining to;

a) a predetermined number of said detecting receivers;

b) a number of said detecting receivers less than said predetermined number when said signal strengths of said predetermined number vary by more than predetermined amounts; and

c) a number of said detecting receivers more than said predetermined number when said signal strengths of said predetermined number vary by less than predetermined amounts.