Detection system
AssigneeParmeko Limited
InventorJohn D. McCann
Life of this patent
Estimating the term…
Abstract
A system for monitoring the position of a receptor reradiator in a surveillance zone having a first means for transmitting a first signal through the zone, and a receptor reradiator operable in response to reception of said signal to radiate at least one reply signal which is a function of the first signal and of the position of said receptor reradiator in the zone. There is also a receiver for receiving the reply signal, means controlled by the receiver, dependent upon the reply signal to indicate the position of the receptor reradiator in the zone, and an alarm triggerable by the receiver responsive to the latter for receiving the reply signals.
Claims21
A method of monitoring the position in a surveillance zone of an electromagnetic wave receptor reradiator with signal mixing capability, comprising the steps of radiating simultaneously first and second energy fields through said zone for causing said receptor reradiator to radiate at least one reply signal which is a function of energy fields and of the position of the receptor reradiator in the zone and wherein said energy fields are established respectively from spaced apart locations adjacent the edges of said zone, said first energy field is produced by a first high frequency signal and said second energy field is produced by a second high frequency signal of a different frequency to said first high frequency signal;
- detecting in said zone the presence of said reply signal;
- and indicating the position of the receptor reradiator in the zone and triggering an alarm in response to the detection of said reply signal.
A surveillance system for monitoring the position in a surveillance zone of an electromagnetic wave receptor reradiator with signal mixing capability, comprising in combination:
- a source of a first high frequency signal;
- a first means coupled to said source for radiating through said zone a first energy field corresponding to said first high frequency signal;
- a source of a second high frequency signal of a different frequency to said first high frequency signal;
- second means coupled to said source for radiating through said zone a second energy field corresponding to said second high frequency signal, said first and second means establishing said energy fields respectively from spaced apart locations adjacent the edges of said zone;
- a receptor reradiator operable to detect said energy fields and to radiate at least one reply signal which is a function of said signals and of the position of said receptor reradiator in the zone;
- a receiver for detecting said reply signal, means controlled by the receiver in dependence upon detection of said reply signal to indicate the position of the receptor reradiator in the zone;
- and an alarm coupled to the receiver for providing an alarm signal responsively to the receiver detecting the reply signal.
A method of detecting the presence in a surveillance zone of an electromagnetic wave receptor reradiator with signal mixing capability, comprising the steps of simultaneously radiating first, second and third energy fields through said zone for causing said receptor reradiation to radiate at least one reply signal which is a function of said energy fields, wherein said first energy field is produced by a microwave signal and second and third energy fields are produced by low frequency signals relative to said microwave signal;
- said second and third energy fields being radiated into said zone at spaced apart locations adjacent the edges of said zone, and said reply signal being a function of the position of said receptor reradiator;
- detecting in said zone the presence of said reply signal;
- triggering an alarm in response to detection of said reply signal;
- and indicating the position of the receptor reradiator in the zone.
A surveillance system for detecting the presence in a surveillance zone of an electromagnetic wave receptor reradiator with signal mixing capability comprising in combination:
- a source of a first microwave signal;
- means coupled to said source for radiating through said zone a first energy field corresponding to said microwave signal;
- a source of a second signal;
- means coupled to said source for radiating through said zone a second energy field corresponding to said second signal;
- a source of a third signal;
- means coupled to said source for radiating through said zone a third energy field corresponding to said third signal, wherein said second and third signals are at different, low frequencies relative to the microwave signal;
- said means radiating said second and third energy fields being positioned respectively at spaced apart locations adjacent the edges of said zone and said reply signal being a function of the position of said receptor;
- a receptor reradiator operable to detect said energy fields and to radiate at least one reply signal which is a function of said signals;
- a receiver for detecting said reply signal;
- an alarm coupled to the receiver for providing an alarm signal responsively to the receiver detecting the reply signal;
- and means controlled by the receiver in dependence upon detection of said reply signal to indicate the position of the receptor reradiator in said zone.
Dependencies are inferred from the claim text.