Police alarm system

• US 3,922,678 A
• Filed: 03/25/1974
• Issued: 11/25/1975
• Est. Priority Date: 03/25/1974
• Status: Expired due to Term

• Current Assignee: Marvin A Frenkel
• Original Assignee: Marvin A Frenkel
• Inventors: Frenkel, Marvin A.
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Berger, Richard E.
• Application Number:
  US05/454,570
• Time in Patent Office: 610 Days
• Field of Search: 343/112PT,112D,112TC,1CS,112R 340/24 325/29,54
• US Class Current: 342/457
• CPC Class Codes: G01S 2205/06 Emergency
• CPC Class Codes: G01S 5/02521 using a radio-map

Abstract

A method and apparatus for selectively determining the location at which an emergency alarm signal is generated, the method comprising the steps of arranging a plurality of wireless signal detectors in a pattern wherein they are spaced such that their respective circular regions of signal detection overlap one another, and detecting a transmitted wireless signal in a zone corresponding to any one of the overlapping regions by at least two detectors whose overlapping regions define the zone in which the signal is transmitted.

Claims

1. Apparatus for selectively determining a location at which an alarm signal is generated, comprising:

a fixed array of wireless signal detecting means having a substantially identical sensitivity for receiving a generated alarm signal, said detecting means being equidistantly spaced from one another in substantially rows and columns along a selected topography; and

at least one wireless signal generating means anywhere on said selected topography for transmitting an alarm signal of sufficient intensity to activate at least two adjacent ones of said detecting means simultaneously, said generating means generating a signal whose distance-of-transmission at said intensity substantially corresponds to the distance at which said detecting means are equidistantly spaced from one another.

2. Apparatus as claimed in claim 1, wherein said detecting means includes a plurality of receiver means tuned to respond to a signal of selected frequency, said generating means including at least one mobile transmitter tuned to generate a signal at said selected frequency.

3. Apparatus as claimed in claim 1, including a map of said selected topography, said map indicating thereon (a) the locations at which said detecting means are positioned, and (b) imaginary circles having respective centers corresponding to the locations of said detecting means, said circles corresponding in size to the distance at which said detecting means are equidistantly spaced from one another and having mutually overlapping sectors which define respective zones in any of which a transmitted wireless signal is detectable by at least two of said detecting means which correspond to the overlapping sectors defining the zone in which the signal is transmitted.

4. Apparatus as claimed in claim 3, including a control station at which said map is stored, and receiver means at said control station, said detecting means including relaY means for transmitting signals to respective ones of said receiver means to indicate at said control station which of said detecting means are activated by said generating means, each said relay means and its corresponding receiver means being associated with one another by a common frequency differing from the common frequency of the others of the corresponding relay means and receiver means.

5. Apparatus as claimed in claim 4, wherein said receiver means includes a plurality of visual indicators which are positioned in said zones, respectively, and are responsive to said detecting means.

6. Apparatus as claimed in claim 1, including at least one further fixed array of detecting means situated in a substantially vertical plane above selected corresponding ones of said detecting means, said arrays of detecting means in combination constituting a three-dimensional signal locating system.

7. In a method of selectively determining a location at which an alarm signal is generated, comprising the steps of:

arranging a plurality of wireless signal detectors having a substantially identical sensitivity for receiving a generated alarm signal in a fixed array of rows and columns along a selected topography such that said detectors are equidistantly spaced from one another;

generating a wireless signal anywhere on said selected topography of sufficient intensity to activate at least two adjacent ones of said detectors simultaneously, and controlling the intensity of the generated wireless signal such that its distance-of-transmission substantially corresponds to the distance at which said detectors are equidistantly spaced from one another.

8. A method as claimed in claim 7, including tuning said detectors such that they respond to a wireless signal of selected frequency, and generating said wireless signal at said selected frequency by a transmitter movable along said selected topography.

9. A method as claimed in claim 7, including marking on a map of said selected topography (a) the locations at which said detectors are positioned, and (b) imaginary circles having respective centers corresponding to the locations of said receivers and respective radial dimensions corresponding in size to the distance at which said detectors are spaced from one another, said circles having mutually overlapping sectors which define respective zones in any of which a transmitted wireless signal is detectable by at least two of said detectors which correspond to the overlapping sectors defining the zone in which the signal is transmitted.

10. A method as claimed in claim 9, including storing said map at a control station, and positioning on said map in said zones visual indicators which are responsive to said detectors respectively, to define visually which of the latter are activated by the generated wireless signal.

11. In a method of selectively determining a location at which an alarm signal is generated, comprising the steps of:

a. developing a wireless signal detecting pattern; and

b. detecting a wireless alarm signal by said pattern, said step (a) comprising;

transmitting a wireless signal omni-directionally at a plurality of spaced locations along a selected topography;

detecting on said topography signals of identical minimum intensity along respective imaginary closed loops surrounding each of said spaced locations;

developing on a map of said topography said spaced locations and the loci of said closed loops which surround said spaced locations, respectively;

selecting said spaced locations such that selected portions of said closed loops overlap one another; and

positioning on said topography at said spaced locations respective wireless signal detectors each having a region of detection corresponding to the closed loop surrounding it, the overlapping loop portions defining discrete zones in any of which a transmitted wireless signal is detectable simultaneously by at least two detectors corresponding to the overlaPping loop portions which define the zone in which the wireless signal is transmitted, said step (b) comprising;

transmitting a wireless alarm signal in any of said zones; and

detecting said wireless alarm signal by at least two detectors simultaneously which correspond to the zone in which the alarm signal is transmitted.

12. A method as claimed in claim 11 wherein each of said detectors is a relay unit having a receiver portion and a transmitter portion, each of said receiver portions having a substantially identical sensitivity for receiving transmitted alarm signal;

and including tuning each of said receiver portions to receive an identical frequency, tuning each of said transmitter portions to transmit respective wireless signals at frequencies differing from one another, positioning a plurality of receivers at a control station which correspond respectively to each of said detectors, and tuning each of said receivers to receive respective signals corresponding in frequency to the signal transmitted by the transmitter portion of the detector associated therewith.

13. A method as claimed in claim 12, including positioning in each of said zones on said map a respective visual indicator, and electrically coupling said indicators to respective combinations of said receivers which correspond to and define the zones in which the visual indicators are positioned.