Electromagnetic field perimeter detection apparatus
First Claim
1. Detection apparatus comprising:
- at least one receiving conductor for sensing an electromagnetic field;
at least three mutually spaced elongate transmitting conductors each coupled to a source of electromagnetic energy and cooperating to produce a desired electromagnetic field along the length of said receiving conductor;
alarm indicating circuitry coupled to said at least one receiving conductor for providing an alarm indication in response to a sensed disturbance of said electromagnetic field,said source of electromagnetic energy for each transmitting conductor comprising an AC voltage source of selected amplitude and phase, the selection of amplitude and phase determining the configuration of the overall electromagnetic field produced by said transmitting conductors, there being a non-zero phase relationship between the voltage sources of at least two of said transmitting conductors.
1 Assignment
0 Petitions
Accused Products
Abstract
Detection apparatus comprising a plurality of elongate transmitting conductors each coupled to a source of electromagnetic energy and arranged for producing an electromagnetic field along the length thereof, at least one receiving conductor arranged alongside the plurality of transmitting conductors for sensing the electromagnetic field produced thereby, and alarm indicating circuitry coupled to the at least one receiving conductor for providing an alarm indication in response to a sensed disturbance of the electromagnetic field, the source of electromagnetic energy for each transmitting conductor comprising an AC voltage source of selected amplitude and phase, the selection of amplitude and phase determining the configuration of the overall electromagnetic field produced by the transmitting conductors, there being a non-zero phase relationship between the voltage sources of at least two of the transmitting conductors.
15 Citations
29 Claims
-
1. Detection apparatus comprising:
-
at least one receiving conductor for sensing an electromagnetic field; at least three mutually spaced elongate transmitting conductors each coupled to a source of electromagnetic energy and cooperating to produce a desired electromagnetic field along the length of said receiving conductor; alarm indicating circuitry coupled to said at least one receiving conductor for providing an alarm indication in response to a sensed disturbance of said electromagnetic field, said source of electromagnetic energy for each transmitting conductor comprising an AC voltage source of selected amplitude and phase, the selection of amplitude and phase determining the configuration of the overall electromagnetic field produced by said transmitting conductors, there being a non-zero phase relationship between the voltage sources of at least two of said transmitting conductors. - View Dependent Claims (2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 26)
-
-
7. Detection apparatus comprising:
-
receiver means for detecting an electromagnetic field; transmitter means operative in an intermittent continuous wave mode for producing an electromagnetic field in a protected region, said transmitter means including at least three mutually spaced elongate transmitting conductors each coupled to a source of electromagnetic energy and cooperating to produce a desired electromagnetic field along the length of said receiver means; said source of electromagnetic energy for each transmitting conductor comprising an AC voltage source of selected amplitude and phase, the selection of amplitude and phase determining the configuration of the overall electromagnetic field produced by said transmitting conductors, there being a non-zero phase relationship between the voltage sources of at least two of said transmitting conductors; alarm indicating circuitry coupled to said receiver means and being operative to detect small changes in said electromagnetic field over a wide dynamic range.
-
-
14. Detection apparatus comprising:
-
a plurality of receiver means for detecting an electromagnetic field; transmitter means operative for producing an electromagnetic field in a protected region, said transmitter means including at least three mutually spaced elongate transmitting conductors each coupled to a source of electromagnetic energy and cooperating to produce a desired electromagnetic field along the length of said receiver means; said source of electromagnetic energy for each transmitting conductor comprising an AC voltage source of selected amplitude and phase, the selection of amplitude and phase determining the configuration of the overall electromagnetic field produced by said transmitting conductors, there being a non-zero phase relationship between the voltage sources of at least two of said transmitting conductors; each of said receiver means defining a sensing zone; alarm indicating circuitry coupled to said plurality of receiver means for receiving signals from said sensing zones and including; means for determining the time relationship between signals from said sensing zones; and means for providing an alarm indication in response to receipt of at least two signals of similar shape having a non-zero time difference within predetermined limits. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
-
-
24. Detection apparatus comprising:
-
a plurality of receiving conductors for sensing an electromagnetic field; at least three elongate transmitting conductors each coupled to a source of electromagnetic energy and cooperating to produce a desired electromagnetic field along the length of said plurality of receiving conductors; said source of electromagnetic energy for each transmitting conductor comprising an AC voltage source of selected amplitude and phase, the selection of amplitude and phase determining the configuration of the overall electromagnetic field produced by said transmitting conductors, there being a non-zero phase relationship between the voltage sources of at least two of said transmitting conductors; each of said receiving conductors defining a sensing zone; alarm indicating circuitry coupled to said receiving conductors for receiving signals from said sensing zones and including; means for sensing the time relationship between signals from said sensing zones; and means for providing an alarm indication in response to receipt of at least two signals having a non-zero time difference within predetermined limits. - View Dependent Claims (25)
-
-
27. Detection apparatus comprising:
-
at least one receiver conductor for sensing an electromagnetic field; at least three elongate transmitting conductors each coupled to a source of electromagnetic energy and cooperating to produce a desired electromagnetic field along the length of said at least one receiver conductor; said source of electromagnetic energy for each transmitting conductor comprising an AC voltage source of selected amplitude and phase, the selection of amplitude and phase determining the configuration of the overall electromagnetic field produced by said transmitting conductors, there being a non-zero phase relationship between the voltage sources of at least two of said transmitting conductors; alarm indicating circuitry coupled to said at least one receiving conductor for providing an alarm indication in response to predetermined disturbance of the electromagnetic field, and wherein said at least three transmitting conductors are operative to transmit a pulsed continuous wave signal. - View Dependent Claims (28, 29)
-
Specification