U.S. patent application number 10/429602 was filed with the patent office on 2008-09-04 for fiber optic security system for sensing the intrusion of secured locations.
Invention is credited to Thomas E. Browning, Mark C. Phillips.
Application Number | 20080210852 10/429602 |
Document ID | / |
Family ID | 42270519 |
Filed Date | 2008-09-04 |
United States Patent
Application |
20080210852 |
Kind Code |
A1 |
Browning; Thomas E. ; et
al. |
September 4, 2008 |
Fiber optic security system for sensing the intrusion of secured
locations
Abstract
A sensor for a security system is disclosed to detect intrusions
at one or more predetermined locations wherein each location
includes a moveable member which must be moved in order to intrude
the location. The system includes a fiber network routed in close
proximity to one or more locations. The sensor comprises a sensor
housing for being disposed at a location to detect a predetermined
movement of the moveable member from a secure position to an
unsecured position, and means for mounting the sensor housing in a
stationary position at the location without a physical connection
to the moveable member. The sensor housing includes a fiber inlet
and a fiber outlet, and a fiber chamber for receiving a
predetermined sensor fiber of the fiber network being routed
through the sensor housing. The sensor has a sensor actuator for
engaging the sensor fiber to generate an intrusion signal upon
detecting predetermined movement of the moveable member, and
causing the intrusion signal to be transmitted along the sensor
fiber to a processor whereby the intrusion and location of the
intrusion may be determined by the processor. Preferably, the
sensor includes a magnetic actuator having a magnetic attraction to
the moveable members whose interruption causes activation of the
sensor and generation of the intrusion signal.
Inventors: |
Browning; Thomas E.;
(Spartanburg, SC) ; Phillips; Mark C.; (Woodruff,
SC) |
Correspondence
Address: |
McNair Law Firm, P.A.;*Intrusion Of Secured Locations
P.O. Box 10827
Greenville
SC
29603
US
|
Family ID: |
42270519 |
Appl. No.: |
10/429602 |
Filed: |
May 5, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60456687 |
Mar 21, 2003 |
|
|
|
Current U.S.
Class: |
250/227.14 ;
250/227.15; 340/540; 340/550 |
Current CPC
Class: |
E02D 29/1481 20130101;
G08B 13/08 20130101; H02G 9/10 20130101; G08B 13/186 20130101; G08B
13/124 20130101 |
Class at
Publication: |
250/227.14 ;
250/227.15; 340/550; 340/540 |
International
Class: |
G01J 1/04 20060101
G01J001/04; G08B 21/00 20060101 G08B021/00; G08B 13/00 20060101
G08B013/00; G01J 1/42 20060101 G01J001/42; G01J 5/08 20060101
G01J005/08 |
Claims
1. A security system for detecting intrusion at a plurality of
predetermined locations having movable numbers which must be moved
in order to intrude into said location, and a fiber network
composed of a plurality of optic fibers routed in close proximity
to said locations, said system comprising: a plurality of sensors
disposed at said locations contacting an optic fiber from said
fiber network selected as a sensor fiber, said sensors detecting
movement of said moveable numbers and attempted physical intrusions
at said locations and generating intrusion signals when one or more
sensors are activated thereby; a processor in communication with
said sensor fiber for receiving said intrusion signals from said
activated sensors and determining the location of each activated
sensor; a communication output operatively associated with said
processor for communicating an identification of each activated
sensor and the location of each said activated sensor; and said
sensors being disposed adjacent said moveable members in a
non-contacting manner, and said sensors detecting a predetermined
movement of said moveable members from a secured position to an
unsecured position whereby intrusion signals are generated without
physical connection between said sensors and said moveable
members.
2. (canceled)
3. The system of claim 1 wherein said sensors include magnetic
attractions between said sensors and said moveable members whose
interruption causes activation of said sensors and generation of
said intrusion signals.
4. The system of claim 3 wherein said sensors include a
reciprocating sensor actuator having a deactivated position and an
activated position, said sensor actuator engaging said sensor fiber
when said moveable members are in an unsecured position causing
sensor activation and said intrusion signal to be generated.
5. The system of claim 4 wherein said moveable sensor actuator
forms a predetermined bend in said sensor fiber when activated to
produce a characteristic intrusion signal that is readily
recognizable by said processor to reliably detect a sensor
activation and sensor location.
6. The system of claim 5 wherein said sensor actuator includes a
first contoured abutment with a prescribed contour for engaging
said sensor fiber, and said prescribed contour producing said
predetermined bend in said sensor fiber upon activation of said
sensor.
7. The system of claim 6 wherein said sensor includes a sensor
housing having a fiber chamber, said sensor fiber being routed
through said fiber chamber with a natural bend producing no
attenuation in said sensor fiber when said sensor is deactivated,
and said sensor actuator engaging said natural bend of said sensor
fiber to form said predetermined bend in said sensor fiber when
said sensor is activated causing attenuation in said sensor fiber
and generation of said intrusion signal.
8. The system of claim 7 wherein said fiber chamber includes a
fiber receiving space defined between said first contoured abutment
of said sensor actuator and a second contoured abutment through
which said sensor fiber passes.
9. The system of claim 8 wherein said second contoured abutment
engages said sensor fiber to produce said natural bend when said
sensor is deactivated, and said first contoured abutment engages
said sensor fiber to produce said predetermined bend when said
sensor is activated.
10. The system of claim 9 wherein said first and second contoured
abutments are carried by said movable actuator.
11. The system of claim 10 including a biasing element connected
between said movable actuator and said sensor housing which forces
said first contoured abutment into engagement with said sensor
fiber when said sensor is activated.
12. The system of claim 7 wherein said sensor housing includes a
fiber inlet and a fiber outlet so that said sensor fiber is routed
through said inlet, through said fiber chamber where said sensor
fiber assumes said natural bend, and through said fiber outlet.
13. A security system for detecting intrusion at one or more
predetermined locations wherein each location includes a moveable
member which must be moved in order to intrude into said location,
said system comprising: a fiber network routed in proximity to said
one or more locations; a sensor disposed at each of said one or
more locations for detecting a predetermined movement of said
moveable member to an unsecured position at said location; a
predetermined fiber of said fiber network being physically
connected to each said sensor to provide a sensor fiber; said
sensor being mounted in a stationary position at said location
without a mechanical connection to said moveable member; said
sensor generating an intrusion signal upon detecting said
predetermined movement of the moveable member at one location, said
intrusion signal being transmitted along said sensor fiber; a
processor in communication with said fiber receiving said intrusion
signal for determining the location of an activated sensor; and
communication output providing information of an activation and
location of said sensor in response to said processor receiving
said intrusion signal.
14. The system of claim 13 wherein said sensors include magnetic
attractions between said sensors and said moveable members whose
interruption causes activation of said sensors and generation of
said intrusion signal.
15. The system of claim 13 wherein said sensors include moveable
sensor actuators having a deactivated position and an activated
position, said sensor actuator engaging said sensor fiber when said
moveable members are in an unsecured position causing sensor
activation and said intrusion signal to be generated.
16. The system of claim 15 wherein said moveable sensor actuator
forms a predetermined bend in said sensor fiber when activated to
produce a characteristic intrusion signal that is readily
recognizable by said processor to reliably detect a sensor
activation and sensor location.
17. The system of claim 15 wherein said sensor includes a sensor
housing having a fiber chamber, said optic sensor fiber being
routed through said fiber chamber with a natural bend producing no
attenuation in said sensor fiber when said sensor is deactivated,
and said sensor actuator engaging said natural bend of said sensor
fiber to form said predetermined bend in said sensor fiber when
said sensor is activated causing attenuation in said sensor fiber
and generation of said intrusion signal.
18. The system of claim 17 wherein said fiber chamber includes a
fiber receiving space defined between said first contoured abutment
of said sensor actuator and a second contoured abutment between
which said sensor fiber passes.
19. The system of claim 18 wherein said second contoured abutment
engages said sensor fiber to produce said natural bend when said
sensor is deactivated, and said first contoured abutment engages
said sensor fiber to produce said predetermined bend when said
sensor is activated.
20. The system of claim 19 wherein said sensor housing includes a
fiber inlet and a fiber outlet so that said sensor fiber is routed
through said inlet, through said fiber chamber where said sensor
fiber assumes said natural bend, and through said fiber outlet.
21. A sensor for a security system detecting intrusions at one or
more predetermined locations wherein each location includes a
moveable member which must be moved in order to intrude said
location, and a fiber network routed in close proximity to said one
or more locations, said sensor comprising: a sensor housing for
being disposed at a location to detect a predetermined movement of
said moveable member from a secure position to an unsecured
position; means for mounting said sensor housing in a stationary
position at said location without a physical connection to said
moveable member; a fiber inlet and a fiber outlet formed in said
housing; a fiber chamber in said housing for receiving a
predetermined fiber of said fiber network being routed through said
sensor housing; and said sensor having a sensor actuator for
generating an intrusion signal upon detecting said predetermined
movement of the moveable member at a location causing said
intrusion signal to be transmitted along said fiber of said fiber
network to a processor; whereby the intrusion and location of the
intrusion may be determined by said processor.
22. The system of claim 21 wherein said sensor includes a magnetic
actuator having a magnetic attraction to said moveable members
whose interruption causes activation of said sensor and generation
of said intrusion signal.
23. The system of claim 21 wherein said sensor includes a moveable
sensor actuator having a deactivated position and an activated
position, said sensor actuator engaging said sensor fiber when said
moveable member is in an unsecured position causing sensor
activation and said intrusion signal to be generated.
24. The system of claim 23 wherein said moveable sensor actuator
forms a predetermined bend in said sensor fiber when activated to
produce a characteristic intrusion signal that is readily
recognizable by said processor to reliably detect a sensor
activation and sensor location.
25. The system of claim 24 wherein said fiber chamber is
constructed to receive said sensor fiber when routed through said
fiber chamber with a natural bend producing no attenuation in said
sensor fiber when said sensor is deactivated, and said sensor
actuator engaging said natural bend of said sensor fiber to form
said predetermined bend in said sensor fiber when said sensor is
activated causing attenuation in said sensor fiber and generation
of said intrusion signal.
26. The system of claim 25 wherein said fiber chamber includes a
fiber receiving space defined between said first contoured abutment
of said sensor actuator and a second contoured abutment between
which said sensor fiber passes.
27. The system of claim 26 wherein said second contoured abutment
engages said sensor fiber to produce said natural bend when said
sensor is deactivated, and said first contoured abutment engages
said sensor fiber to produce said predetermined bend when said
sensor is activated.
28. The system of claim 27 wherein said first and second contoured
abutments are carried by said movable actuator.
29. The system of claim 28 including a biasing element connected
between said movable actuator and said sensor housing which forces
said first contoured abutment into engagement with said sensor
fiber when said sensor is activated.
30. A method for detecting intrusion into a protected location
using a fiber network connected to an optical reflectometer
processor, said method comprising: providing a sensor for detecting
a predetermined movement of a moveable member which must be moved
in order to intrude into said location; providing a connection
between a fiber of the fiber network and said sensor so that a
predetermined movement of said moveable member causes said sensor
to be activated and to generate an intrusion signal which is
transmitted to said reflectometer device through said fiber; and
processing said intrusion signal to determine location of said
sensor.
31. The method of claim 30 including using an existing utility
fiber network carrying at least one of voice and data signals, and
providing connection to a fiber of said fiber network as a sensor
fiber for generating and transmitting said intrusion signal.
32. The method of claim 31 including providing said connection
between said fiber and said sensor without making a physical
connection between said fiber and said moveable member.
33. The method of claim 32 including providing a sensor having a
moveable actuator which contacts said fiber causing generation of
said intrusion signal in response to movement of said moveable
member to said unsecured position.
34. The method of claim 33 including providing a magnetic
attraction between said moveable actuator and said moveable member
which is broken when said moveable member is moved to said
unsecured position.
35. The method of claim 30 including arranging said fiber to have a
natural bend producing generally no attenuation when said sensor is
deactivated, and deforming said natural bend to a predetermined
bend when said sensor is activated to generate said intrusion
signal having a discernible characteristic wave form.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a fiber optic security system and
sensor for detecting the intrusion of a secured location and, more
particularly, to such a system and sensor wherein each secured
location includes a moveable member which secures the location and
a fiber optic network routed in close proximity to the location
wherein the sensor senses movement of the moveable member to an
unsecured position, and the system detects the occurrence and
location of the intrusion.
[0002] With the increase in terrorist events needed to be prevented
in the United States, the need for effective security systems to
sense intrusion into secured areas has greatly increased. In
particular, a security system for the protection of a vast system
of underground utilities accessed by manholes with removeable
covers is needed. A highly effective system to detect entrance into
these underground spaces and utilities is needed in order to
protect against vandalization and terrorist activities within these
spaces and the spaces to which these underground utilities lead.
Heretofore, it has been known to use fiber optic sensors to detect
theft of articles, intrusion into protected areas, as well as a
variety of other purposes.
[0003] For example, U.S. Pat. No. 4,369,437 discloses a security
and alarm apparatus to detect movement of a cover for a fill pipe
leading to an underground fuel tank wherein an alarm signal is
transmitted if the cover is disturbed. However, the system does not
use fiber optics, requires electrical power at the location, and is
generally not suited for a wide area security system.
[0004] U.S. Pat. No. 5,055,827 discloses an fiber optic security
system to prevent the theft of appliances located in a network of
computers, terminals, and associated peripheral devices. When one
of the appliances is moved, light attenuation of a fiber cable
results in a signal being generated. However, this system requires
physical connection of the optic fiber to the appliance and the
system is not suitable for detecting events in a wide geographical
area.
[0005] U.S. Pat. No. 5,434,557 discloses an intrusion detection
system having at least one optical cable which is usually part of a
fence. When the intruder exerts force on the fence, the movement
actuates a mechanical device exerting force on the cable which is
detected and actuates an alarm. Here again, the system requires
physical connection to the moveable part of the fence and the fiber
optic cable requires electrical power at the location, and is
generally not suitable for wide geographical areas.
[0006] U.S. Pat. No. 5,594,239 discloses a measuring system for
monitoring buildings, train sections, or the like, consisting of a
beam wave guide bending sensor. Basically, the system utilizes the
deflection of a beam wave length to detect movement of the building
structure.
[0007] U.S. Pat. No. 4,814,562 discloses a pressure sensor which
utilizes pressure on a fiber optic in order to measure
pressure.
[0008] U.S. Pat. No. 5,592,149 discloses a security fence which
utilized an optical wire woven into the fence material whereupon
movement of the fencing by an intruder causes the fiber wire to
move and actuate an alarm signal. Once again physical connection is
required between the optic fiber and the moveable member. U.S. Pat.
No. 4,777,476 discloses another security fence wherein the optic
fiber is physically connected to the moveable member to detect
movement of a moveable member and intrusion to generate an alarm.
U.S. Pat. No. 4,829,286 discloses yet another security fence
requiring physical connection of the optic fiber to a moveable
member in order to generate a signal caused by an intruder moving
the fiber optic. U.S. Pat. No. 5,049,855 discloses a security
screen system wherein an optical fiber is woven into the screen
mesh and distortion of the screen material by an intruder causes an
alarm signal.
[0009] Not only do the above security systems and sensors require a
physical connection between the optic fiber and the moveable
member, but the systems require electrical power at the location
sought to be protected making them wholly unsuitable for many
security applications, including wide geographical area systems.
More importantly, no provision is made for identifying the location
of an intrusion event where large numbers of sensors are
utilized.
[0010] Accordingly, an object of the present invention is to
provide a security system for detecting intrusion at a secured
location using a fiber optic network and sensor by which the
occurrence and location of an intrusion even can be reliably
determined.
[0011] Another object of the present invention is to provide a
security system for detecting an intrusion at any one of a
plurality of secured locations using an fiber optic network in
close proximity to the locations wherein the actuation of a sensor
by an intruder and the exact location of the sensor and the
intrusion can be determined at any one of the locations.
[0012] Another object of the present invention is to provide a
sensor for a security system which can be utilized with an fiber
optic network requiring no electrical power and requiring no
physical connection to a moveable member having a secured position
in order to detect movement of the moveable member to an unsecured
position.
[0013] Yet another object of the invention is to provide a security
system using a pre-existing fiber optic network which carries voice
and/or data transmissions wherein a fiber of the network may be
connected to a series of sensors and to an optical reflectometer so
that the occurrence and location of an intrusion may be
determined.
SUMMARY OF THE INVENTION
[0014] The above objectives are accomplished according to the
present invention by providing a security system for detecting
intrusion at a plurality of predetermined locations using a fiber
network composed of a plurality of optic fibers routed in close
proximity to the locations. The system comprises sensors disposed
at the locations contacting an optic fiber from the fiber network
selected as a sensor fiber for detecting physical intrusions at the
locations and generating intrusion signals when one or more sensors
are activated. A processor in communication with the sensor fiber
receives the intrusion signals from the activated sensors and
determines the location of each activated sensor. A communication
output is operatively associated with the processor for
communicating identification of each activated sensor and the
location of each activated sensor. Preferably, the locations
include a moveable member which must be moved in order to intrude
into the location, and the sensors are disposed adjacent to the
moveable members in a non-contacting manner. The sensors detect a
predetermined movement of the moveable members from a secured
position to an unsecured position whereby intrusion signals are
generated without physical connection between the sensors and the
moveable members. Advantageously, the sensors may include magnetic
attractions between the sensors and the moveable members whose
interruption causes activation of the sensors and generation of the
intrusion signals. In the illustrated embodiment, the sensors
include a reciprocating sensor actuator having a deactivated
position and an activated position. The sensor actuator engages the
sensor fiber when the moveable members are in an unsecured position
causing sensor activation and the intrusion signal to be generated.
The moveable sensor actuator forms a predetermined bend in the
sensor fiber when activated to produce a characteristic intrusion
signal that is readily recognizable by the processor to reliably
detect a sensor activation and sensor location. In an advantageous
aspect, the sensor actuator includes a first contoured abutment
with a prescribed contour for engaging the sensor fiber, producing
a predetermined bend in the sensor fiber upon activation of the
sensor. In the illustrated embodiment, the sensor includes a sensor
housing having a fiber chamber. The sensor fiber is routed through
the fiber chamber with a natural bend producing no attenuation in
the sensor fiber when the sensor is deactivated. The sensor
actuator engages the natural bend of the sensor fiber to form the
predetermined bend in the sensor fiber when the sensor is activated
causing the characteristic attenuation in the sensor fiber and
generation of the intrusion signal. The fiber chamber includes a
fiber receiving space defined between the first contoured abutment
of the sensor actuator and a second contoured abutment through
which the sensor fiber passes. The second contoured abutment
engages the sensor fiber to produce the natural bend when the
sensor is deactivated, and the first contoured abutment engages the
sensor fiber to produce the predetermined bend when the sensor is
activated. Preferably, the first and second contoured abutments are
carried by the movable actuator. A biasing element connected
between the movable actuator and the sensor housing forces the
first contoured abutment to engage the sensor fiber when the sensor
is activated. The sensor housing includes a fiber inlet and a fiber
outlet so that the sensor fiber is routed through the inlet,
through the fiber chamber where the sensor fiber assumes the
natural bend, and through the fiber outlet.
[0015] In accordance with a method for detecting intrusion into a
protected location using a fiber network connected to an optical
reflectometer processor, the method comprises providing a sensor
for detecting a predetermined movement of a moveable member which
must be moved in order to intrude into the location. Next; a
connection between a fiber of the fiber network and the sensor is
made so that a predetermined movement of the moveable member causes
the sensor to be activated and to generate an intrusion signal
which is transmitted to the reflectometer device through the fiber.
Next, the method includes processing the intrusion signal to
determine the location of the sensor and hense, the intrusion.
Advantageously, the method includes using existing utility fiber
networks which carry voice and data signals, and providing
connection to a fiber of the fiber network as a sensor fiber for
generating and transmitting the intrusion signal. The connection
between the fiber and the sensor is made without making a physical
connection between the fiber and the moveable member. The method
includes providing a sensor having a moveable actuator which
contacts the fiber causing generation of the intrusion signal in
response to movement of the moveable member to the unsecured
position; and providing a magnetic attraction between the moveable
actuator and the moveable member which is broken when the moveable
member is moved to an unsecured position. Advantageously, the
method includes arranging the fiber to have a natural bend
producing generally no attenuation when said sensor is deactivated,
and deforming said natural bend to a predetermined bend when the
sensor is activated to generate the intrusion signal having a
discernible characteristic wave form resulting from the bend.
DESCRIPTION OF THE DRAWINGS
[0016] The construction designed to carry out the invention will
hereinafter be described, together with other features thereof.
[0017] The invention will be more readily understood from a reading
of the following specification and by reference to the accompanying
drawings forming a part thereof, wherein an example of the
invention is shown and wherein:
[0018] FIG. 1 is a schematic diagram illustrating one embodiment of
a security system according to the invention employing fiber optic
networks wherein a plurality of intrusion sensors are connected in
series in the networks and wherein the networks includes an optical
time domain reflectometer (OTDR);
[0019] FIG. 2 is perspective view of an optic intrusion sensor
according to the invention mounted to a manifold of a manhole to
detect the removal of the manhole cover wherein the cover is shown
in a secured position;
[0020] FIG. 3A is a section view of an optic intrusion sensor
according to the invention mounted to a manifold of a manhole to
detect the removal of the manhole cover wherein the cover is shown
in a secured position which activates the sensor;
[0021] FIG. 3B is a section view of an optic intrusion sensor
according to the invention mounted to a manifold of a manhole to
detect the removal of the manhole cover wherein the cover is shown
in an unsecured position which activates the sensor;
[0022] FIG. 4A is a top plan view of an optic intrusion sensor
according to the invention with the cover removed and the sensor
actuator in a deactivated position;
[0023] FIG. 4B is a top plan view of an optic intrusion sensor
according to the invention with the cover removed and the sensor
actuator in an activated position;
[0024] FIG. 4C is a partial view of a sensor actuator of the optic
intrusion sensor illustrating a contoured surface of the actuator
which produces a characteristic bend in an optic fiber used as a
sensor fiber so that a characteristic signal is produced by an
optical timed domain reflectometer connected to the fiber;
[0025] FIG. 5 is a schematic illustration of three of the intrusion
sensors wired in a fiber optic network, and a graphic display of a
normal OTDR signal produced when the sensors are not activated;
[0026] FIG. 6 is a graphic display of the OTDR signal when one
sensor is activated;
[0027] FIG. 7 is a graphic display of the OTDR signal when two of
the sensors are activated; and
[0028] FIG. 8 is a graphic display of the OTDR signal when all
three of the sensors in the optical network are activated.
DESCRIPTION OF A PREFERRED EMBODIMENT
[0029] Referring now to the drawings, the invention will now be
described in more detail.
[0030] As can best be seen in FIG. 1, an optical fiber security
system, designated generally as A, is illustrated. The security
system includes a remote processor, designated generally as 10, for
processing an intrusion signal to determine the occurrence and
location of the intrusion. The processor may, for example, include
an optical time domain reflectometer (OTDR) 12 of the type
routinely utilized to monitor maintenance of fiber optic network
systems. Typically, the OTDR is used to sense a fiber breakage,
water seepage, irregular bends, or other defects in one or more
optical fibers of the fiber network along the routing path of the
network. For example, in large municipalities it is not uncommon
for there to be 1,000 miles of fibers in an optical fiber network.
However, as opposed to these conventional uses, an expedient of the
present invention is to utilize the OTDR to detect the occurrence
and exact location of an individual attempting an intrusion into a
secured location. In the illustrated embodiment of FIG. 1, the OTDR
is connected to two fiber optic networks 15a and 15b. Each network
includes a plurality of secured locations comprised of a series of
utility manholes 16. A transponder 17 may be located at the end of
each fiber optic network. The manholes include manhole manifolds
18, and manifold covers 20 which cover and secure the manholes. For
purposes of illustration, and not limitation, three manholes 16a,
16b, and 16c of network 15a will be discussed to illustrate the
invention. Of course, any number of manholes as are disposed in
close proximity to the fiber optic network may be placed in series
in the security system. Typically, fiber optic networks run through
the underground tunnels to which access is provided through the
manholes. Of course, many other type of utility cables, channels,
water and sewage are typically routed through the underground
tunnels.
[0031] As can best be seen in FIGS. 2, 3A, and 3B, a sensor,
designated generally as 24, is attached in a stationary position by
means of an adjustable bracket 26 to an interior sidewall 28 of
each manifold. Each sensor includes a sensor housing 30 attached to
mounting bracket 26 which, in turn, is mounted to interior sidewall
28 by means of conventional fasteners 32 extending through
adjustable slots 34 of bracket 26. In this manner, the vertical
position of sensor 24 can be adjusted relative to a top flange 20a
of manhole cover 20 so as to be mounted out of contact but closely
adjacent to the flange of the manhole cover, for reasons explained
more fully below. FIG. 3A shows the manhole cover in a secured
position wherein the sensor is deactivated. FIG. 3B shows the
manhole cover moved to an unsecured position wherein the sensor is
activated.
[0032] As can best be seen in FIGS. 4A and 4B, intrusion sensor
housing 30 includes a fiber entrance 38 and a fiber exit 40. A
moveable sensor actuator 46 is slidably carried within a cutout
slide cavity 48. A spring 50 is attached to the sensor actuator at
52 on one end and to a post 54 affixed to housing 30 at an opposite
end. In the illustrated embodiment, sensor actuator 46 includes a
magnet 56 and a first arcuate abutment 58 made integral with magnet
56 by means of a clip 60. Sensor actuator 46 also includes a second
arcuate abutment 62. Arcuate abutments 58, 62 define a fiber
receiving space 64 therebetween. Receiving space 64 includes an
entrance trumpet 66, an outlet trumpet 68, and a throat 70
therebetween. A fiber 14a which is removed from the fiber network,
is routed through the sensor and the fiber receiving space.
Preferably the sheath of the fiber is removed so that only the
optic fiber 14a is routed through the receiving space of the sensor
actuator. The sensor is illustrated in a deactivated position in
FIG. 4A wherein fiber 14a is routed through the housing inlet,
fiber receiving space 64, and the fiber outlet. It can be seen that
the fiber passing through the fiber receiving space assumes a
natural or circular curve 14b over a major portion within the
sensor. In the deactivated position moveable sensor actuator 46 is
maintained as shown in FIG. 4A by the magnetic force of attraction
between magnet 56 and manhole cover 20 in its secured position.
When the manhole cover is moved to the unsecured position, a
predetermined distance from magnet 56, the magnetic attraction is
broken and sensor actuator 46 moves vertically to place a
predetermined bend 72 in the fiber 14a, as can best be seen in FIG.
4B. In order that a predetermined and characteristic bend is placed
in the fiber that will emit a uniform signal anytime the sensor is
activated, first arcuate abutment 58 includes a contour at 74.
Preferably contour 74 is provided in the form of a tangential flat
surface that creates a controlled radius in the bend 72 of the
fiber that causes a characteristic intrusion signal shape to be
received by the OTR device and displayed, e.g., see signal 90a at
FIG. 5. By providing a consistent and uniform fiber bend and
attenuation, the intrusion signal can be detected and recognized on
the display screen of the OTR device in a reliable manner.
[0033] In the preferred embodiment, actuator 46 includes magnet 56
which is maintained in the deactivated position by proximity of
sensor 24 to the metal flange of manhole cover 20. Spring 50 is
tensioned when moveable actuator 46 is in the deactivated position
of FIG. 4A. When the magnetic force is broken, the spring tension
pulls the actuator downwards to place predetermined bend 72 in
optic fiber 14a. In the event that a nonmetallic material is used
for the manhole manifold and cover, a metallic material insert may
be placed in an area of the manhole cover which will maintain
actuator 46 in a retracted, deactivated position of FIG. 4A. The
manhole cover has a secure position fitted within the top opening
of the manifold, and an unsecured position when it is moved from
the secured position which is sufficient to break the magnetic
attraction. In order to eliminate false detections, sensor 24 is
mounted a sufficient distance from the manhole cover, e.g.,
one-half inch, so that fluttering of the cover by traffic, etc.,
does not break the magnetic attraction between actuator 46 and the
cover. However, when the cover is moved a sufficient, predetermined
distance to an unsecured position which indicates an intrusion, the
magnetic attraction is broken and sensor actuator 46 moves to the
activated position of FIG. 4B whereupon optic fiber 14a is
deflected changing its reflection properties and attenuation.
Variations on the sensor actuator and types of sensors, may be had,
although it is advantageous that there be no mechanical or direct
connection between the optic signal wire used in the sensor and the
moveable member needed to be moved by an intruder, and that no
electrical power be required for the sensor operation.
[0034] When a characteristic intrusion signal is produced, such as
90a, 90b, or 90c, the OTR device measures the distance to the
signal, or signals. The sensor locations are mapped by the
processor system so that a display or printout of the sensor and
its exact geographical location is produced. In this manner, the
exact point of the intrusion is determined so that a timely
response may be made at the location of the intrusion.
[0035] As can best be seen in FIG. 1, OTDR is connected to a
computer system C having a computer processor 80 connected to a
monitor 82 with a display screen 84. A normal OTDR signal 86 is
transmitted from the OTDR to computer processor 80, and displayed
on monitor 82. Conventional input devices, keyboard 88, and mouse
89, may be provided for operating computer system C. Of course,
other means of displaying the OTDR signal may be used, such as a
dedicated display device.
[0036] Referring to FIGS. 5 through 8, the operation of the system
and identification of activated sensors will now be discussed. FIG.
5 illustrates display screen 84 of monitor 82 displaying a normal
signal 86 which is received in the absence of an OTDR intrusion
event, or other fiber disturbance signal. Optic sensor fiber 14a is
commonly routed through each of sensors 24a, 24b, 24c. As
illustrated in FIG. 5, none of the sensors are activated so a
normal signal 86 is displayed on the screen. In FIG. 6, sensor 24b
is activated, and an OTDR intrusion signal 90b is displayed showing
that an intrusion event has occurred at sensor 24b. Since the
location of sensor 24b is known and mapped, the location of the
intrusion is determinable. FIG. 7 shows the graphic display screen
60 when an instruction event has occurred at both sensor 24b and
24c, as indicated at signal 90b and 90c. FIG. 8 illustrates graphic
display of OTDR signals at 90a, 90b, and 90c when an intrusion
event has occurred at all three sensors 24a, 24b, and 24c. Since
the locations of sensors 24a, 24b, 24c are predetermined and
mapped, the location of the intrusion event is known by knowing
which sensor is activated. It is noted that intrusion signals 90a,
90b, and 90c have a characteristic shape predetermined by the shape
of bend 72 created in optic sensor fiber 14a by contour 74 of
abutment 58. This characteristic signal shape is reliably
recognized as an intrusion event signal. Typically, the OTDR will
also have other characteristic signals which represent other fiber
disturbances and resulting attenuation. For example, a 0.5 db power
drop indicates an intrusion, a 1 db power drop indicates water
seepage, a 0.3 db power drop indicates an irregular bend, a fiber
breakage is represented by a straight spike, etc.
[0037] Thus, it can be seen that a highly advantageous construction
for a security system and sensor can be had according to the
invention where preexisting or new fiber networks can be utilized
in close proximity to locations needed to be secured whereby
sensors connected in series with an OTDR device can be utilized to
determine the occurrence and location of an intrusion anywhere
along the fiber optic network. For example, if a municipality has
1,000 miles of fiber optic network routed through tunnels
accessible by manholes, each manhole may be provided with a sensor
to determine whether it has been moved to an unsecured position. In
this manner, the entire network of manholes and fiber optic
network, as well as other underground utilities, may be secured
against terrorists or other acts of invasion, vandalism, etc.
[0038] While a preferred embodiment of the invention has been
described using specific terms, such description is for
illustrative purposes only, and it is to be understood that changes
and variations may be made without departing from the spirit or
scope of the following claims.
* * * * *