Space surveillance apparatus with sound source and method of short-range space surveillance
First Claim
1. A short-range surveillance device, comprising:
- at least one source of sonic energy having a membrane of a preselected diameter and a main direction of radiation;
said at least one source of sonic energy emitting sonic radiation of a preselected wavelength;
a driver circuit for driving said at least one source of sonic energy;
an evaluation circuit for emitting an alarm signal in response to at least any one of motion and sojourn, or both, within a surveillance space of an object more solid than ambient air;
said surveillance space having a length dimension extending in said main direction of radiation;
said length dimension being at least approximately determined by the relationship;
space="preserve" listing-type="equation">L=D.sup.2 /(4λ
)wherein L=said length dimension, D=said preselected membrane diameter, and λ
=said preselected wavelength of said sonic radiation; and
said driver circuit serving for driving said source of sonic energy selectively either continuously at a constant preselected wavelength, continuously in frequency-modulation, pulsedly at a constant preselected wavelength or puslsedly in frequency-modulation.
1 Assignment
0 Petitions
Accused Products
Abstract
A space surveillance apparatus includes at least one source of sonic radiation driven by a driver circuit as well as a processing or evaluation circuit. Upon movement of an object, or presence of a foreign object within a monitored space, the processing circuit triggers an alarm signal. Each sonic source defines the volume of its own monitored space, according to the equation:
L=D.sup.2 /(4λ),
wherein:
L=Length of main direction of radiation of the monitored space;
D=Diameter of diaphragm of sonic source; and
λ=Wavelength of acoustic wave.
The driver circuit drives the sonic source either in continuous mode, or in pulsed mode, and either at a constant wavelength or at a variable wavelength, i.e. in frequency modulation.
10 Citations
26 Claims
-
1. A short-range surveillance device, comprising:
-
at least one source of sonic energy having a membrane of a preselected diameter and a main direction of radiation; said at least one source of sonic energy emitting sonic radiation of a preselected wavelength; a driver circuit for driving said at least one source of sonic energy; an evaluation circuit for emitting an alarm signal in response to at least any one of motion and sojourn, or both, within a surveillance space of an object more solid than ambient air; said surveillance space having a length dimension extending in said main direction of radiation; said length dimension being at least approximately determined by the relationship;
space="preserve" listing-type="equation">L=D.sup.2 /(4λ
)wherein L=said length dimension, D=said preselected membrane diameter, and λ
=said preselected wavelength of said sonic radiation; andsaid driver circuit serving for driving said source of sonic energy selectively either continuously at a constant preselected wavelength, continuously in frequency-modulation, pulsedly at a constant preselected wavelength or puslsedly in frequency-modulation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
-
-
24. A method for monitoring a surveillance space, comprising the steps of:
-
employing a driver circuit for driving at least one source of sonic energy having an impedance; driving said at least one source of sonic energy selectively either continuously at a constant preselected wavelength, continuously in frequency-modulation, pulsedly at a constant preselected wavelength or pulsedly in frequency-modulation such that said impedance is altered by an object in said surveillance space; monitoring said impedance of said at least one source of sonic energy; comparing said impedance with a reference value; and generating an alarm signal when said impedance departs from said reference value by more than a threshold value. - View Dependent Claims (25)
-
-
26. A short-range surveillance device, comprising:
-
at least one source of sonic energy having a membrane of a preselected diameter and defining a main direction of radiation; said at least one source of sonic energy emitting sonic radiation of a preselected wavelength; a driver circuit for driving said at least one source of sonic energy; an evaluation circuit for emitting an alarm signal in response to at least one of motion and sojourn, or both, of an object which is more solid than ambient air and present within a surveillance space; said surveillance space having a predeterminate length dimension extending in said main direction of radiation and dependent upon said preselected diameter of said membrane and said preselected wavelength of said sonic radiation emitted by said at least one source of sonic energy; said length dimension being at least approximately determined by the relationship;
space="preserve" listing-type="equation">L=D.sup.2 /(4λ
),wherein L=said predeterminate length dimension of said surveillance space, D=said preselected diameter of said membrane, and λ
=said preselected wavelength of said sonic radiation;said driver circuit driving said source of sonic energy selectively such as to emit either continuous or pulsed sonic radiation of said preselected wavelength or continuous or pulsed frequency-modulated sonic radiation; a current-measurement resistor connected in circuit with the at least one source of sonic energy; said at least one source of sonic energy passing an electrical current through said current-measurement resistor during operation of said at least one source of sonic energy; said electric current being subject to variations when said object more solid than ambient air is present in said surveillance space within said predeterminate length dimension; and a comparator circuit of said evaluation circuit being operatively connected to said current-measurement resistor and responding to said variations above a preset upper threshold value whenever said object more solid than ambient air is present in said surveillance space within said predeterminate length dimension.
-
Specification