Follow-up system for moving bodies

• US 4,954,836 A
• Filed: 11/17/1987
• Issued: 09/04/1990
• Est. Priority Date: 09/08/1987
• Status: Expired due to Fees

• Current Assignee: Susumu Sakuma
• Original Assignee: Susumu Sakuma
• Inventors: Sakuma, Susumu
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Issing, Gregory C.
• Application Number:
  US07/121,430
• Time in Patent Office: 1,022 Days
• Field of Search: 342/450, 342/451, 342/457, 342/463-465, 342/386, 342/445, 342/423
• US Class Current: 342/450
• CPC Class Codes: G01S 1/68 Marker, boundary, call-sign, or like beacons transmitting signals not carrying directional information
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: G08B 21/0297 Robbery alarms, e.g. hold-up alarms, bag snatching alarms
• CPC Class Codes: G08B 25/016 Personal emergency signalling and security systems emergency non-personal manually actuated alarm activators G08B25/12

Abstract

A system follows up or traces a moving body accompanied by a radio signal transmitter which constantly generates a radio signal of a predetermined frequency or is adapted to generate such a radio signal when the user manually operates the transmitter should an emergency arise. The system includes two different antenna networks, one comprising a plurality of non-directional antennae disposed substantially evenly over a specific area, always ready to receive the radio signal which will or may be transmitted from anywhere in the area, and the other comprising directional antennas mounted at several points in the area. In response to the radio signal being monitored by one or more of non-directional antennae, at least two of directional antennae come into operation and two different directions in which the respective directional antennae show the maximum field strength are detected with field strength meters attached thereto, which makes it possible to determine an exact position of the signal source or the moving body according to triangular surveying. A computer may be of help to the operation of the system.

Claims

1. A system for locating a moving body within a predetermined area, said moving body being accompanied by a radio signal transmitter, said transmitter having a predetermined range of transmission and transmitting a signal of predetermined frequency, said system comprising

a first antenna network and a second antenna network, said first antenna network comprising a plurality of non-directional antennae located at points disposed substantially evenly over said predetermined area, said second antennae network comprising a plurality of directional antennae located at predetermined points disposed within said predetermined area;

said non-directional antennae being located such that one or more of said non-directional antennae is always within the range of transmission of said transmitter;

each of said directional antennae being provided with means for rotation and means for measuring the strength of signals received by said directional antennae;

controlling means activated by said signal of predetermined frequency received by one or more of said non-directional antennae;

said controlling means, when activated, directing rotation of said rotation means of two of said directional antennae until the strength of signals received by said directional antennae is maximized;

said controlling means indicating the relative rotation of directional antennae rotation;

said moving body being locatable by triangulation of the relative rotation of said directional antennae;

said controlling means comprising associating pairs of directional antennae with individual non-directional antennae and said controlling means associating location points with said antennae;

whereby when said controlling means is activated, said controlling means can automatically locate the moving body relative to the antennae networks and relative to points of location of said antennae in said predetermined area; and

map information means, said controlling means associating said antennae locations with map information from said map information means regarding said predetermined area, whereby, when said controlling means associates locations of said antennae and relative rotation of said directional antennae is associated with the map information, said moving body is located.

2. The system as claimed in claim 1, wherein said transmitter transmits identification information such that said controlling means may determine identity as well as location of the moving body.