perimeter security sensor technology

8/17/2019 Perimeter Security Sensor Technology

1/109

for

Defense Advanced Research Projects

Agency (DARPA)Joint Program Steering Group

Arlington, irginia

Prepared !y

"#S$ $ast

$lectronic Security Systems

$ngineering Division

"orth %harleston, South %arolinaDistri&ution Statement A

Approved for Pu&lic Release' Distri&ution is unlimited

*

Perimeter Security Sensor +echnologies

and&oo-


2/109

Perimeter Security Sensor Technologies Handbook

PR$.A%$

P/RP0S$'

This Handbook has been developed to provide military and law enforcement securitymanagers, and specialists with a reference of current perimeter security sensor technologies,

capabilities, limitations, and integration methods. The Handbook provides a compendium of

sensor technologies and an explanation of each technology’s operating principles andapplications, as well as integration techniques that can be used to enhance perimeter security and

intrusion detection planning.

S%0P$'

Most of the capabilities, sensors and devices currently in use in the perimeter securityfield are available as ommercial!"ff!The!#helf $"T#% products and have been successfully

integrated into a wide range of operating systems.

The data presented in the Handbook has been restricted to those elements of a security

system that relate to perimeter security and intrusion detection sensor technology. The

Handbook does not include information on computer or access control equipment nor is itintended to provide an all!inclusive list of sensor suppliers or equipment models.

&lthough new or improved equipment is continually being developed and introduced intothe marketplace, and a market survey was conducted in an attempt to present a balanced

representation of the current state of available technologies, the fundamental principles and

applications of intrusion detection have not changed. 'irtually all sensors are based on the core

principle of establishing and(or monitoring a norm and detecting(signaling a change in the norm,above or below, or within a preset threshold.

)nformation included within this Handbook on specific sensors and manufacturers isderived from information received in response to a request for information placed in the

ommerce *usiness +aily $*+% on March , -/. The specification and capabilities data

included in #ection Three of the Handbook is the information provided by those manufacturersor vendors who responded to the ommerce *usiness +aily request. This information has not

been altered or edited. The 0.#. government did not conduct an independent test of any of these

sensor systems and, therefore, does not warrant, guarantee or endorse any of these devices.

&dditional product information may be obtained from the manufacturers listed in #ection 1our of the Handbook.

#ensors under development are not included in this Handbook.

P0#"+S 0. %0"+A%+'


3/109


Defense Advanced Research Projects Agency (DARPA)

Joint Program Steering Group, Arlington, irginia

Mr. )rv #mietan

2rogram Manager 3oint 2rogram #teering 4roup $32#4%

"aval %ommand, %ontrol and 0cean Surveillance %enter, #n Service $ngineering 1 $ast

("#S$ $ast)

P202 !o3 4455

"orth %harleston, South %arolina 561455

Mr. 3erry &. 5oenig, ode 6

Head, 7lectronic #ecurity #ystems 7ngineering +ivision$89:% 6!;69<

Mr. =arry Taylor, ode 6 &hief 7ngineer, 7lectronic #ecurity #ystems 7ngineering +ivision

$89:% 6!;6-:

%omments may &e for7arded to'

>)#7 7ast&ttn? 7lectronic #ecurity #ystems +ivision

2.". *ox -99orth harleston, #


4/109


+A!8$ 0. %0"+$"+S

S$%+#0" 0"$ #"+R0D/%+#0"

-.- 4oal

-.< "rgani@ation-.: "perational Aequirements

-.6 #ystem )ntegration

-.; +etection 1actors-./ #ensor ategories

-. Technology #olutions

-.8 2erformance haracteristics-. 7nvironmental onsiderations

-.-9 &larm Monitoring #ystems

-.-- &larm &ssessment

-.-< #ensor )ntegration-.-: ommunications

-.-6 2ower #upply

-.-; ost onsiderations-.-/ #ensor &pplications

S$%+#0" +90 +$%"080G: R$#$9S

Page +echnology


5/109



6/109


S$%+#0" 0"$

#"+R0D/%+#0"

2 G0A8

This Handbook is intended to be used as a sensor selection reference during the

design and planning of perimeter security systems. The Handbook contains acompendium of sensor technologies that can be used to enhance perimeter security and

intrusion detection in both permanent and temporary installations and facilities.

25 0RGA"#;A+#0"

The Handbook is organi@ed into four sections. #ection "ne includes this

"verview of a do@en factors to be considered prior to selecting a suite of perimeter detection sensors. #ection Two consists of a description of each of the twenty!eight $


7/109


complexes include? logistic depots, ship and aircraft unloading and servicing facilities,

vehicle staging areas, personnel billeting compounds, communications sites andheadquarters compounds. &lthough the personnel and vehicle screening challenges at

each site will vary with the nature of the environment and the potential threat, the role of

perimeter security will be similar in all cases.

*asically stated, the role of a perimeter security system is fourfold? deter, detect,

document and deny(delay any intrusion of the protected area or facility. )n the case of

&merican facilities and complexes located in foreign countries, this challenge is further complicated when 0.#. forces cannot patrol or influence the environment beyond the

immediate EfencelineE. )n situations such as these, the area within the fenceline $the

&rea of Aesponsibility ! &"A%, should be complemented by an area of securitysurveillance beyond the fence, $preferably a cordon sanitaire% wherein the perimeter, from

an early warning perspective is extended outward. This is particularly essential in

situations where the host government security forces cannot provide a reliable outer

security screen, or the area to be secured abuts a built!up industrial, business, public or residential area.

26 S:S+$> #"+$GRA+#0"

The integration of sensors and systems is a maDor design consideration and is best

accomplished as part of an overall system(installation(facility security screen. &lthoughsensors are designed primarily for either interior or exterior applications, many sensors

can be used in both environments. 7xterior detection sensors are used to detect

unauthori@ed entry into clear areas or isolation @ones that constitute the perimeter of a protected area, a building or a fixed site facility. )nterior detection sensors are used to

detect penetration into a structure, movement within a structure or to provide knowledge

of intruder contact with a critical or sensitive item.

2? D$+$%+#0" .A%+0RS

#ix factors typically affect the 2robability of +etection $2d% of most areasurveillance $volumetric% sensors, although to varying degrees. These are the? -% amount

and pattern of emitted energyF


8/109


2@ S$"S0R %A+$G0R#$S

Exterior intrusion detection sensors detect intruders crossing a particular

boundary or entering a protected @one. The sensors can be placed in clear @ones, e.g.

open fields, around buildings or along fence lines. 7xterior sensors must be resilient

enough not only to withstand outdoor weather conditions, such as extreme heat, cold,dust, rain, sleet and snow, but also reliable enough to detect intrusion during such harsh

environmental conditions.

7xterior intrusion sensors have a lower probability of detecting intruders and a

higher false alarm rate than their interior counterparts. This is due largely to many

uncontrollable factors such as? wind, rain, ice, standing water, blowing debris, randomanimals and human activity, as well as other sources to include electronic interference.

These factors often require the use of two or more sensors to ensure an effective intrusion

detection screen.

Interior intrusion detection sensors are used to detect intrusion into a building or

facility or a specified area inside a building or facility. Many of these sensors are

designed for indoor use only, and should not be exposed to weather elements.

)nterior sensors perform one of three functions? $-% detection of an intruder

approaching or penetrating a secured boundary, such as a door, wall, roof, floor, vent or window, $


9/109


applications, intrusion detection sensors are used in conDunction with a set of physical

barriers and personnel(vehicles access control systems. +etermining which sensor$s% areto be employed begins with a determination of what has to be protected, its current

vulnerabilities, and the potential threat. &ll of these factors are elements of a Aisk

&ssessment, which is the first set in the design process.

2 P$R.0R>A"%$ %ARA%+$R#S+#%S?

)n the process of evaluating individual intrusion detection sensors, there are atleast three performance characteristics which should be considered? 2robability of

+etection $2+%, 1alse &larm Aate $1&A%, and 'ulnerability to +efeat $i.e. typical

measures used to defeat or circumvent the sensor%.

& maDor goal of the security planner is to field an integrated )ntrusion +etection

#ystem $)+#% which exhibits a low 1&A and a high 2+ and is not susceptible to defeat.

Probability of Detection provides an indication of sensor performance in detecting

movement within a @one covered by the sensor. 2robability of detection involves not

only the characteristics of the sensor, but also the environment, the method of installationand adDustment, and the assumed behavior of an intruder.

False Alarm Rate indicates the expected rate of occurrence of alarms which arenot attributable to intrusion activity. 1or purposes of this Handbook, G false alarms and

Gnuisance alarms are included under the overall term G1alse &larm Aate, although

technically, there is a distinction between the two terms. & nuisance alarm is an alarmevent which the reason is known or suspected $e.g. animal movement(electric

disturbance% was probably not caused by an intruder. & false alarm is an alarm when the

cause is unknown and an intrusion is therefore possible, but a determination after the fact

indicates no intrusion was attempted. However, since the cause of most alarms $bothnuisance(false% usually cannot be assessed immediately, all must be responded to as if

there is a valid intrusion attempt.

ulnerability to Defeat is another measure of the effectiveness of sensors. #ince

there is presently no single sensor which can reliably detect all intruders, and still have an

acceptably low 1&A, the potential for Gdefeat can be reduced by designing sensorcoverage using multiple units of the same sensor, and(or including more than one type of

sensor, to provide overlapping of the coverage area and mutual protection for each

sensor.

2 $"#R0">$"+A8 %0"S#D$RA+#0"S

Most security @ones have a unique set of environmental factors which are taken

into consideration when designing the system, selecting the sensors, and performing the

installation. 1ailure to consider all the factors can result in excessive Gfalse alarmsand(or Gholes in the system.

-!6


10/109


7ach potential intrusion @one, whether it be a perimeter fence, an exterior

entrance, a window, an interior door, a glass partition or a secured room, will have specialGenvironmental factors to be considered. 7xternal @ones are likely to be affected by the

prevailing climate, daily(hourly fluctuations in weather conditions, or random animal

activity as well as man!made Genvironmental factors such as activity patterns, electrical

fields and(or radio transmissions, and vehicle, truck, rail or air movement.

There are a wide variety of other considerations which must be assessed when

placing sensors to monitor the perimeter of an area or building. & fundamentalconsideration is the need to have a well!defined clear(surveillance or isolation @one.

#uch a @one results in a reduction of 1&As caused by innocent people, large animals,

blowing debris, etc. )f fences are used to delineate the clear @one or isolation @one, theyshould be carefully placed, well constructed and solidly anchored, since fences can move

in the wind and cause alarms. onsideration should also be given to dividing the

perimeter into independently alarmed segments in order to locali@e the area of the

possible intrusion and improve response force operations.

)nternal @one sensors can also be impacted by a combination of external stimuli,

such as machinery noise and(or vibrations, air movement caused by fans or air conditioning(heating units, and changes in temperature to mention a few. Many of these

and others will be discussed in the individual Technology Aeviews presented in #ection

Two.

24 A8AR> >0"#+0R#"G S:S+$>S

)n addition to the "ff!the!#helf )ntrusion Technology that is discussed in this

Handbook, there is a variety of alarm monitoring systems available. &lthough each

system is unique in the number and variety of options available, all systems perform the

basic function of annunciating alarms and displaying the alarm locations in some format.The front!end $control function% of most of these systems is configured with standard 68/

or 2entium computer utili@ing Bindows, +"#, 0>)I or "#(< as the operating system.

Many of these systems operate with proprietary software, written by the manufacturer of the security system.

2 A8AR> ASS$SS>$"+

#tate!of!the!art alarm assessment systems provide a visual and an audible

indication of an alarm. The alarm data is displayed in one of two forms ! either as text on

a computer(monitor screen or as symbols on a map representation of the area. Mostsystems offer multiple levels $scales% of maps which can be helpful in guiding security

personnel to the location of the alarm. The urgency of the audible(visual alarm cue can

vary as to the nature of the alarm or the location of the possible intrusion $e.g. high priority versus low priority areas%. )n most security systems, several of these capabilities

are combined to provide the #ecurity "perations enter personnel with a relatively

comprehensive picture of the alarm situation. "ne option offers a visual surveillancecapability which automatically provides the #ecurity &larm Monitor with a real!time

view of the alarm(intrusion @one.

-!;


11/109


25 S$"S0R #"+$GRA+#0"

1rom a technology perspective, the integration of sensors into a coherent security

system has become relatively easy. Typically, most sensor systems have an alarm relay,

from points a, b or c, and may have an additional relay to indicate a tamper condition.This relay is connected to field panels via four wires, two for the alarm relay and two for

the tamper relay, or two wires, with a resistive network installed to differentiate between

an alarm and tamper condition. Most monitoring systems will also provide a means of monitoring the status of the wiring to each device. This is called line supervision. This

monitoring of the wiring provides the user with additional security by indicating if

circuits have been cut or bypassed.

&dditionally, different sensors can be integrated to reduce false alarm rates, and(or

increase the probability of intrusion detection. #ensor alarm and tamper circuits can be

Doined together by installing a logic Gand circuit. This Gand system then requiresmultiple sensors to indicate an alarm condition prior to the field unit sending an alarm

indication. 0sage of the logic Gand circuit can reduce false alarm rates but it may

decrease the probability of detection because two or more sensors are required to detectan alarm condition prior to initiating an alarm .

2< %0>>/"#%A+#0"S

ommunications between the front!end computer and the field elements $sensors,

processors% usually employ a variety of standard communications protocols. A#!68;,A#!


12/109


system. "ften this figure is representative of the hardware cost only, and does not

include the costs of installation, any associated construction or maintenance. >ormally,the costs associated with procuring the sensor components are outweighed by the costs

associated with acquiring and installing the assessment and alarm reporting systems.

2@ S$"S0R APP8#%A+#0"S

Most sensors have been designed with a specific application in mind. These

applications are categori@ed by the environment where they are most commonlyemployed. The two basic environments or categories are 7xterior and )nterior. 7ach of

the two basic categories has a number of sub!sets, such as fence, door, window, hallway,

and room.

The first two of the following set of graphics show a Efamily treeE illustration of

the sensors most applicable to these two environments $exterior(interior%. &s mentioned

previously, some of the technologies can be used in both environments, and consequentlyare shown on both graphics.

-!


13/109


S/PP8$>$"+A8 GRAP#% R$PR$S$"+A+#0"S

PAG$ +0P#%

1 $3terior #ntrusion Sensors

14 #nterior #ntrusion Sensors

1 +ypical #ntrusion Detection Process

15 Sensor Applications >odel ($3terior)

1< Sensor Applications >odel (#nterior)

16 >ilitary Application >odels

1? Airfield

1@ Joint +as- .orce %ompound

1* Port .acility

1 List of Acronyms and Key Terms

-!8


14/109


7xterior )ntrusion #ensors

A p p l i c a t i o n s I n d e x

V I B R A T I O N

T A U T W I R E

C O N T I N U I T Y

M I C R O B E N D I N G /

D I S T U R B A N C E

F I B E R O P T I C

C O A X I A L

C A B L E

M A G N E T I C

P O L Y M E R

S T R A I N S E N S I T I V E

C A B L E S

E - F I E L D

C A P A C I T A N C E

F E N C E

S E N S O R S

B A L A N C E D

P R E S S U R E L I N E

P O R T E D C O A X

B U R I E D L I N E

B U R I E D

F I B E R O P T I C

B U R I E D

G E O P H O N E

I N G R O U N D

S E N S O R S

F E N C E

L I N E

A C T I V E

I N F R A R E D

M I C R O W A V E

P A S S I V E I N F R A R E D

P A S S I V E I N F R A R E D /

M I C R O W A V E

R A D A R

A C O U S T I C S E N S O R

A I R T U R B U L E N C E

V O L U M E T R I C

S E N S O R S

O P T I C A L

I N F R A R E D

M O T I O N

D E T E C T I O N

V I D E O

S E N S O R S

O P E N A R E A

S U R V E I L L A N C E

E X T E R I O R

S E N S O R S

-!


15/109


)nterior )ntrusion #ensors A p p l i c a t i o n s I n d e x

M E C H A N I C A L

S W I T C H

M A G N E T I C

S W I T C H

B A L A N C E D

M A G . S W I T C H

W I N D O W

S E N S O R S

A C O U S T I C

S H O C K

A C O U S T I C /

S H O C K

G L A S S B R E A K

S E N S O R S

W I N D O W

M E C H A N I C A L

S W I T C H

M A G N E T I C

S W I T C H

B A L A N C E D

M A G . S W I T C H

D O O R

S E N S O R S

D O O R

V I B R A T I O N

F I B E R

O P T I C

W A L L

S E N S O R S

W A L L

M I C R O W A V E

P I R

P I R / M W

A U D I O

A C T I V E

U L T R A S O N I C

P A S S I V E

U L T R A S O N I C

V O L U M E T R I C

S E N S O R S

P H O T O

E L E C T R I C

B E A M

S E N S O R S

O P T I C A L

I N F R A R E D

M O T I O N

D E T E C T I O N

V I D E O

S E N S O R S

H A L L W A Y / R O O M

I N T E R I O R

S E N S O R S

-!-9


16/109


+:P#%A8 P$R#>$+$R S$%/R#+: #"+R/S#0" D$+$%+#0"

PR0%$SS

TH7 )>TA0#)"> #7>#"A +7T7T#

)>TA0#)">, &0#7+ *J A"##)>4

"1 TH7 27A)M7T7A K">7

TH7 #)4>&= )# &>&=JK7+ *J

TH7 #7>#"A 2A"7##"A T"

+)117A7>T)&T7 *7TB77>=74)T)M&T7 &>+ 0>B&AA&>T7+

H&A&T7A)#T)# A7=&T)>4 T"

)>TA0#)">

">7 TH7 #)4>&= )# +7T7AM)>7+

T" *7 H&A&T7A)#T) "1 &>)>TA0#)"> &TT7M2T &> &=&AM

)# 47>7A&T7+ "A TH7 "MM&>+

2"#T )# &=7AT7+

&1T7A TH7 "MM&>+ 2"#T )#

&=7AT7+, TH7 A7#2">#7 1"A7

)# >"T)1)7+ 1"A #7##M7>T

&

*

+

-!--


17/109


$B+$R#0R S$"S0R APP8#%A+#0"S >0D$8This example is typical of a secured facility employing various detection sensors.

The illustration shows how sensors can operate in conDunction with each other, and hypothetically

where sensors would be installed to enhance intrusion detection probability.

2A"27ATJ +7=)M)T)>4

=)>7

*0117A K">7

L&T)'7 )>1A&A7+

LM)A"B&'7

L2H"T" 7=7TA)

17>7 *&AA)7A

L')*A&T)">

LT&0T B)A7

L1)*7A "2T)

L#TA&)> #7>#)T)'7L7=7TA) 1)7=+

L&2&)T&>7

)>4A"0>+ #7>#"A#

L*0A)7+ =)>7

L*0A)7+ 47"2H">7

L1)*7A "2T)

L"&I)&= &*=7

')+7" M"T)">

+7T7T)">

2"AT&= &22A"&H &A7&

LM)A"B&'7

L2#)'7 )>1A&A7+

L2)A ( M)A"B&'7

LM7H&>)&= #B)TH

LM&4>7T) #B)TH

L*M#

L4=# *A7&5 &"0#T)

L4=# *A7&5 #H"5

LB&== 1)*7A "2T)

LB&== ')*A&T)">

7>TAJ 2")>T

$+""A(B)>+"B(B&==%

#70A7+(=)M)T7+

&7## &A7&

L&0+)"

L2#)'7 )>1A&A7+L2)A ( MB

L0=TA">)

LM)A"B&'7

L2H"T" 7=7TA)

=egend?

&)A T0A*0=7>7

FRONT

GATE

PARKINGLOT

DOOR

WINDOWDOOR

SECURED

ROOM LOADINGDOCK

2ndFLOOR

BUILDINGX

INGROUNDSENSORSFENCE LINE

-!-


18/109


#"+$R#0R S$"S0RS APP8#%A+#0"S >0D$8

The following example is a typical secured room employing various detection sensors.

This illustration demonstrates how sensors operate in conDunction with each other, and where

sensors can be installed to enhance security.

1)*7A "2T) B&==(7)=)>4 #7>#"A#-. ')*A&T)"> B&==(7)=)>4 #7>#"A#6.

'"=0M7TA) #7>#"A#

LM)A"B&'7

L&T)'7 0=TA">)

L&T)'7 )>1A&A7+

L2#)'7 )>1A&A7+

L2#)'7 0=TA">)

L&0+)"


19/109


Military Application Models

• Airfield %omple3

• Joint +as- .orce %ompound

• PortC8ogistics .acility

-!-6


20/109


R U N W A Y

FUEL

OPERATIONS&

MAINTENANCE

U.S. BARRACKS

U.S. RESPONSIBILITY

AREAOF U.S. INTEREST(RESPONSIBILITYOF HOSTCOUNTRY)

WAREHOUSE &TRANSSHIPMENT

PARKINGAREA

TERMINAL

MAINTENANCE BUILDING

Airfield %omple3&A7& "1 0.#. )>T7A7#T $A7#2">#)*)=)TJ "1 H"#T >&T)">%

&A7& "1 A7#2">#)*)=)TJ 27A)M7T7A

H"#T >&T)"> *0)=+)>4#(1&)=)T)7#

WAREHOUSE

-!-;


21/109


HEADQUARTERSCOMPLEX

BARRACKS

ARMS

BLDG

COMMUNICATIONSCENTER

TRAINING&DININGCOMPLEX

SHOP SHOP

GUARD

BARRACKS

U.S. RESPONSIBILITY

AREAOF U.S. INTEREST(RESPONSIBILITYOF HOSTNATION)

Joint +as- .orce %ompound&A7& "1 0.#. )>T7A7#T $A7#2">#)*)=)TJ "1 H"#T >&T)">%

&A7& "1 A7#2">#)*)=)TJ 27A)M7T7A

H"#T >&T)"> *0)=+)>4#(1&)=)T)7#

L O C A L C O M M U N I T Y B U S I N E S S E S

L O C A L C O M M U N I T Y B U S I N E S S

E S

-!-/


22/109


POWER

PLANT

W A R E H O U S E

SHOP

ENTRY

CONTROL

RESPONSIBILITYOF U.S.


PortC8ogistic .acility&A7& "1 0.#. )>T7A7#T $A7#2">#)*)=)TJ "1 H"#T >&T)">%

&A7& "1 A7#2">#)*)=)TJ 27A)M7T7A

LOGISTICS

COORDINATING

CENTER


-!-


23/109


A%R0":>S A"D $: +$R>S

• *M# *alanced Magnetic #witch

•

*+ ommerce *usiness +aily

• T' losed ircuit Television

• onductor Material which transmits electric current.

• "T# ommercial "ff The #helf

• AT athode Aay Tube

• +&A2& +efense &dvanced Aesearch 2roDects &gency

• d* +ecibels

• +TM1 +ual Tone Multi 1requency

• 71) 7lectronic 1requency )nterference

• 7M) 7lectro!Magnetic )nterference

• 1alse &larm &ctivation of sensors for which no cause can be determined.

• 1&A 1alse &larm Aate

• 1#5 1requency #hifting 5ey

• )M+ )mage Motion +etection

• )A )nfrared

• =7+ =ight 7mitting +iode

• ===T' =ow =ight =evel Television

• MB Microwave

• >&A >uisance &larm Aate

• >)#7 ! 7ast "aval ommand, ontrol N "cean #urveillance enter, #n!

Service $ngineering, $ast oast +ivision

-!-8


24/109


• 2+ 2robability of +etection

• 2)A 2assive )nfAared

• A&+&A A&dio +etection &nd Aanging

• A" Aeceiver ut!"ff

• A1 Aadio 1requency

• A

1

)

Aadio 1requency )nterference

• Ax Aeceiver

• T' Television

• Tx Transmitter

• 'M+ 'ideo Motion +etection

$: +$R>S

• &pplications The installation and working environments $e.g. exterior,

interior, hallways, rooms%, and the @one(coverage pattern thatare applicable to a particular sensor. "ther sensors which can

provide complimentary coverage are also cited.

• apacitance The property of two or more obDects which enables them tostore electrical energy in an electrostatic field between them.

• auses for >uisance

&larms

&ctivity(events in which a properly operating sensor generates an alarm not attributable to intentional intrusion

activity, are discussed. These activity(events are typically

caused by Epredictable(knownE changes in the environmentalEnormE, such as vegetation movement, strong(turbulent

weather conditions, and animal activity.

-!-


25/109


• onditions for 0nreliable

+etection

onditions which can lower the probability of detection and

effect the ability of the sensor to fully function. Theseconditions typically include factors such as weather,

background noise, electronic interference, poor surveillance

environment, obstructions, and indiscriminate placement of

EforeignE obDects $e.g. boxes, vehicles%.

• Typical +efeat Measures Typical methods which may be used by an intruder to

bypass(avoid detection.

-!


26/109


S$%+#0" +90

S$"S0R +$%"080G: R$#$9S

This section presents information on twenty!eight )ntrusion +etection #ensor

Technologies. 7ach sensor technology is discussed separately and has beensequenced to move from the more familiar to the more complex. The reviews

have also been grouped to flow from interior point security systems to wall

systems, to controlled area coverage systems, to exterior perimeter systems$including a variety of Gfence systems%, and then to buried Gcordon violation

systems. The last several categories, )mage $'ideo% Motion +etection, Aadar

and &coustic &ir Turbulence represent newer capabilities.

&dditional information, in the form of drawings, is located at the end of each

Aeview. &lthough there are some minor differences in sub!paragraphing in a few

of the technologies, the overall framework and key paragraph headings andcontent are consistent.

The basic format is as follows?

-. )ntroduction

uisance &larms

;. Typical +efeat Measures


27/109


S$%+#0" +90 +$%"080G: R$#$9S

Page +echnology


28/109


+$%"080G: R$#$9 E

>$%A"#%A8 S9#+%

2 #ntroduction' Mechanical switches are used to detect the opening of a protected

door or window. These sensors are contact s!itches that depend on direct physical

operation(disturbance of the sensor to generate an alarm.

52 0perating Principle' Mechanical switches are spring!loaded or plunger devices

that trigger when a door or window is opened.

&A. )n addition, alarms caused by lose fitting or improperly mounted doors or

windows can be aggravated by extreme weather conditions $wind and storms% as well as

seasonal fluctuations in the external and(or internal environment $heating versus air conditioning%.

62 +ypical Defeat >easures' Holding the switch in the Gnormal closed positionwhile opening the door or window will preclude the initiation of an alarm. Typically this

is accomplished with a small piece of metal designed to prevent the switch from

triggering. &lso, taping the switch in the Gclosed position during daytime operations

allows an intruder to return after the alarm has been activated and open the door or window without generating an alarm.


29/109


+$%"080G: R$#$9 E 5

>AG"$+#% S9#+%

2 #ntroduction' Magnetic switches are contact s!itches used to detect the opening

of a door or window and depend on the direct physical operation(disturbance of the

sensor to generate an alarm.

52 0perating Principle' Magnetic switches are composed of two parts ! a two!

position magnetic switch mounted on the interior of a door, window or container frame,and a two!position, magnetically operated switch. The standard switch is designed to be

either normally open or normally closed, depending on the design. Bhen the door(

window is closed, the magnet pulls the switch to its Gnormal non!alarmed position.

Bhen the door( window is opened, the magnet releases the switch, breaking the contactand activating the alarm.

easures' 2enetration of the door or window without movingthe magnet switch mechanism will bypass the alarm device. & second, free!moving and

stronger magnet can be used to imitate the mounted magnet, allowing the door to be

opened without generating an alarm. The location of the switch should not be

observable to a potential intruder, reducing an intruder’s ability to bypass or GDump theterminal.


30/109


+$%"080G: R$#$9 E <

!A8A"%$D >AG"$+#% S9#+% (!>S)

2 #ntroduction' *alanced Magnetic #witches consist of a s!itch assembly with aninternal magnet that is usually mounted on the door(window frame and a balancing "or

external# magnet mounted on the moveable door(window.

52 0perating Principle' Typically, the switch is balanced in the open position

between the magnetic field of the two magnets. )f the magnetic field is disturbed by the

movement of the external magnet, the switch moves to a Gclosed position. Bhen thedoor is in the normal closed position, the magnetic field generated by the biasing magnet

interacts with the field created by the switch magnet, so that the total net effect on the

switch is stable. Bhen the door is opened, the switch falls to one of the contacts,

becoming unstable and generating an alarm.

&A.

62 +ypical Defeat >easures' & distinct advantage to using the balanced magnetic

switch is its inherent ability to counter a common defeat measure used on straight

magnetic sensors. This defeat measure involves placing an external magnet on the switchhousing to hold the internal switch in place while the door or window is opened. The

design of the *alance Magnetic #witch precludes this defeat mechanism from being

effective.


31/109


SWITCH

MAGNETBMS!BMS2

CONDUIT SWITCH

SWITCH

ACTUATING

MAGNET

ACTUATING

MAGNET

TYPICAL BALANCED MAGNETIC SWITCH INSTALLATION

!A8A"%$D >AG"$+#% S9#+%,

DOOR OPENINGABSENCE OF MAGNETIC

FIELD CAUSES BMS TOCHANGE STATE

LOCAL

PROCESSOR


32/109


+$%"080G: R$#$9 E 6

G8ASS!R$A

2 #ntroduction' 4lassbreak sensors monitor glass that is likely to be broken during

intrusion. The sensors are housed in a single unit and mounted on a stable interior

element $wall or ceiling% facing the main glass surface. Three types of sensors are used?acoustic, shock, and a dual technology $shock(acoustic% sensor. Aegardless of which

sensor is used, coverage typically does not exceed -99 square feet of glass surface.

52 0perating Principle' 4lassbreak sensors use a microphone to listen for

frequencies associated with breaking glass. & processor filters out all unwanted

frequencies and only allows the frequencies at certain ranges to be analy@ed. The

processor compares the frequency received to those registered as being associated withthe breaking of glass. )f the received signal matches frequencies characteristic of

breaking glass, then an alarm is generated.


33/109


frequency, it is compared to those associated with glass breakage. )f the signal matches

frequencies characteristic of breaking glass, then a signal is sent to the A'D gate.

The shock portion of the sensor Gfeels for the ; 5H@ frequency in the form of a

shock wave created when glass is broken. Bhen the processor detects this shock, it sends

a signal to the A'D gate. "nce the A'D gate has received both signals an alarm isgenerated.

>"T7? & distinct advantage to this sensor is its incorporation of two 4lassbreak technologies into one sensor. This significantly reduces false alarms from background

noise such as A1) and frequency noise created by office machines.

62 Applications and %onsiderations'

a2 Applications' +epending on the manufacturer’s specifications, acoustic

sensors should be mounted on the window, window frame, wall or ceiling. )f mounted onthe glass, the sensor should be placed in the corner approximately two inches from the

edge of the frame. )f mounted on the wall or ceiling, the sensor should be installed

opposite the window.

4lassbreak sensors should be used in conDunction with contact switches $e.g.,

magnetic switches, balanced magnetic switches% in case intrusion is attempted by openingthe window instead of breaking it.

& volumetric $area monitoring% motion detector should also be incorporated in the protected interior area to detect intrusion(entry by an avenue other than the window. The

volumetric device should be positioned at a point and angle that allows it to look in

toward the window of concern to maximi@e the detection capability.

>"T7? &lthough not recommended, the sensor may be mounted on the window. )f so,

the mounting adhesive should be specified to withstand long exposure to summer heat,

winter cold and condensation that might collect on the window. )t should be noted thata window glass can get as hot as -;9o 1 in the summer and as cold as !:9o 1 in the winter,

therefore, it is essential that the application adhesive meets these specifications.


34/109


&2 %onditions for /nrelia&le Detection' &lthough inappropriate matching

of sensor range capacity to the window si@e and poor location may cause the sensor to beout of effective detection range, the most typical deficiency occurs when the acoustical

characteristics of the room are in conflict with the sensor’s performance specifications.

G#oft acoustic rooms $e.g. carpeted with window drapery% that absorb vibration or by

altering the acoustic characteristics of the Ghard room $e.g., adding window shutters, blinds, draperies, rugs% after the sensor has been tuned can cause detection inadequacy of

the sensor.

>"T7? &s a precaution all windows should be checked for cracks and replaced prior to

installation of a 4lassbreak sensor to ensure that a good frequency signature will be

produced if the window is broken.

c2 %auses for "uisance Alarms' )mproper calibration or installation of an

acoustic 4lassbreak sensor will cause nuisance alarms. )n addition, A1 interference and

sharp impact noises can cause false alarms. &lso, improper application(placement of thesensor or background noise, such as office, industrial and cleaning machinery, can create

noise in the frequency detection range of the sensor.

?2 +ypical Defeat >easures' The detaching(cutting of an opening in the window

or the removal of a window pane $with or without a sensor mounted on it% can bypass the

sensor. The break frequency can be distorted by muffling the sound of the breaking glassreducing the potential for the Gcorrect frequency registered by the sensor.


35/109


G8ASS1!R$A S$"S0R

TYPICAL GLASS " BREAK SENSOR INSTALLATION


36/109


+$%"080G: R$#$9 E ?

P0+0 $8$%+R#% !$A>

2 #ntroduction' 2hoto electric beam sensors transmit a beam of infrared light to a

remote receiver creating an Gelectronic fence. These sensors are often used to Gcover

openings such as doorways or hallways, acting essentially as a trip wire. "nce the beamis broken(interrupted, an alarm signal is generated.

52 0perating Principle' 2hotoelectric beam sensors consist of two components? atransmitter and a receiver. The transmitter uses a =ight 7mitting +iode $=7+% as a light

source and transmits a consistent infrared beam of light to a receiver. The receiver

consists of a photoelectric cell that detects when the beam is present. )f the photo electric

cell fails to receive at least 9O of the transmitted signal for as brief as ; milliseconds$time of an intruder crossing the beam%, an alarm signal is generated.

The beam is modulated at a very high frequency which changes up to -,999 times per second in a pattern that correlates with the receiver’s expectation to guard against a

bypass attempt by using a substitute light source. )n order to bypass the sensor, the angle

of the beam and modulation frequency would have to be matched perfectly.


37/109


generate an alarm. Mirrors can also collect dust, causing refraction(diffusion of the

reflected beam.

62 +ypical Defeat >easures' #tepping over or passing under the signal path will

defeat the intent of the sensor. However, mirrors can be used to counter this vulnerability

by creating a GKig!Kag multiple beam barrier pattern.


38/109


+$%"080G: R$#$9 E @

>#%R09A$ S$"S0RS

2 #ntroduction' Microwave sensors are motion detection devices that

transmit(flood a designated area(@one with an electronic field. & movement in the @one

disturbs the field and sets off an alarm. Microwave #ensors may be used in exterior andinterior applications.

52 0perating Principle' Microwave sensors transmit microwave signals in the GI band. These signals are generated by a 4unn diode operating within pre!set limits that do

not affect humans or the operation of pacemakers. &lthough very little power is used, the

system provides enough energy for a detector to proDect a signal up to 699 feet in an

uninterrupted line of sight. The detection of intrusion is directly related to the +oppler frequency shift principle. Most sensors are tuned to measure the +oppler shift between


39/109


&2 !istatic /nits' The transmitter and receiver for bistatic microwave

sensors are separate units. The detection @one is created between the two units. Theantenna can be configured to alter the signal field $width, height%, creating different

detection @ones. The receiver is programmed to receive signals from the transmitter and

detect a change in the frequencies caused by a movement in the field of coverage. *istatic

microwave sensors transceivers are somewhat limited by poorly defined detection patterns, and nuisance alarms may be a problem if large metal obDects are nearby or if

windy conditions exist.


a2 Applications' Microwave sensors can be used to monitor both exterior areas and interior confined spaces, such as vaults, special storage areas, hallways and

service passageways. )n the exterior setting they can be used to monitor an area or a

definitive perimeter line, as well as to serve as an early warning alert of intruders

approaching a door or wall. )n situations where a well!defined area of coverage isneeded, monostatic microwave sensors should be used. However, monostatic microwave

sensors are limited to 699 feet coverage, while bistatic sensors can extend up to -,;99

feet. To further enhance detection, video motion detection equipment $or another typesensor% can be installed to complement the microwave application. The use of a

companion system, such as video image motion detection, not only provides a second

line of defense, but provides security personnel with an additional tool to assess alarmsand discriminate actual(potential penetrations from false alarms or nuisance events.

&2 %onditions for /nrelia&le Detection' #ince microwave sensors operatein the high frequency spectrum $I band%, close association or proximity to other high

frequency signals can adversely affect the detection reliability of these sensors.

&reas that contain strong emitters of electric fields $radio transmitters% or magnetic fields $large electric motors or generators% can effect the ability of microwave

sensors to function properly, and should be avoided or compensated for by distinct signal

separation.

Kones that contain fluorescent lights can also pose a problem. The ioni@ation

cycle created by fluorescent bulbs can be interpreted by the detector as motion and thus provide false alarms.

#elf generated signal reflection is a common problem caused by improper

placement(mounting. 2ositioning the sensor externally and parallel to the wall rather than imbedding it in the wall will avoid this problem.

&lso, large metal obDects which can reflect the signal and(or provide Gdead pockets should be kept out of the detection @one, as should equipment whose operation

involves external movement or rotating functions.

c2 %auses for "uisance Alarms' *ecause of the high frequencies at which

microwaves travel, the signal(sensor is not affected by moving air, changes in


40/109


temperature or humidity. However, the high frequency allows the signal to easily pass

through standard walls, glass, sheet rock, and wood. This can cause false alarms to begenerated by movement adDacent to, but outside the protected area. onversely, it is

essential to test for, note, and compensate for any dead spots $areas of no detection%

created by metal obDects such as dumpsters, shipping crates, trash cans, and electrical

boxes. These dead spots create ideal areas for intrusion attempts. )n addition, signalsreflected off these type obDects(materials can Gextend sensor coverage to areas not

intended to be covered, thus creating the potential for false alarms.

?2 +ypical Defeat >easures' &n intruder with some degree of periodic access to

the denied area may be in a position to conduct Fwalk tests or otherwise cause(observe

the alarm activation pattern, and determine nominal detection coverage patterns, therebyidentifying a possible low detection approach path. )n addition, an intruder advancing at

a deliberately slow rate of movement, who takes maximum advantage of any obscuring,

blocking or signal absorbing characteristics associated with the surveillance environment

can reduce the probability of detection. However, regular calibration of the sensor$s%,sanitation of the area, and the use of another type of sensor can substantially increase the

probability of detection.

+:P#%A8 80"G RA"G$ D$+$%+#0" PA++$R" .0R >0"0S+A+#%

>#%R09A$ S$"S0RS

#RANGE WILL $ARY% DEPENDING UPON DESIGN

TOP $IEW

'"!'' FT. MINIMUM RCO POINT

ACTI$E DETECTION CUT"OFF

2''"'' FT. MAXIMUM


41/109


DETECTION PATTERN

+:P#%A8 S0R+ RA"G$ >0"0S+A+#% >#%R09A$

D$+$%+#0" PA++$R"

TOP $IEW

2(*.+)

,' (-+)

+:P#%A8 !#S+A+#% >#%R09A$ D$+$%+#0" PA++$R"

# LENGTH AND WIDTH OF DETECTION PATTERNS WILL $ARY% DEPENDING UPON

DESIGN.

# THE MICROWA$E SENSORS CAN BE MOUNTED IN A DUAL CONFIGURATION TO

PRO$IDE A GREATER PROBABILITY OF DETECTION.

!''"!&'' FT.

FT

& FT

( FT

, FT

2 FT

! FT

( FT

2 FT

' FT2 FT

( FTTOP $IEW

SIDE $IEW

("(' FT


42/109


MICROWA$E DEAD /ONE

TYPICALLY !' TO ' FT

STACKED MICROWA$E CONFIGURATION

O$ERLAP OF MICROWA$E /ONES

X X X

X

X

XFENCE

XX X

FENCE

X X

D

2D

D 0 LENGTH OF DEAD /ONE

>#%R09A$ S$"S0R ;0"$S

MICROWA$E BEAM

(SIDE $IEW)

DEAD /ONE


43/109


PARALLEL CONFIGURATION

XXXX XX X

XX XX X X X

T

T

R

R

XXXX XX X

XX XX X

INNER FENCE

X X

BASKETWEA$E CONFIGURATION

R

T

R

T T

R R

T

!#S+A+#% >#%R09A$ 8A:0/+ %0".#G/RA+#0"S

TRANSMITTER

RECEI$ERMICROWA$E BEAM

!#S+A+#% >#%R09A$ S$"S0R


44/109


+$%"080G: R$#$9 E *

9A88 #!RA+#0"

2 #ntroduction' 'ibration sensors are designed to be mounted on walls, ceilings

and floors and intended to detect mechanical vibrations caused by chopping, sawing,

drilling, ramming or any type of physical intrusion attempt that would penetrate thestructure on which it is mounted.

52 0perating Principle' Transducers designed to detect the low frequency energy$vibrations% typically generated during a physical intrusion attempt via the surrounding

walls, roof or floor are mounted directly to the inner walls of the protected @one, and

detect the change in the normal Gvibration profile. Two basic types of transducers are

used to detect changes? pie@oelectric transducers and mechanical transducers. *othtypes convert the seismic vibrations detected to electrical signals proportional to the

vibrations. The signals are then sent through a screening filter which determines if the

signal corresponds to the signal spectrum typical of an intrusion attempt. )f the frequencyis characteristic of an intrusion attempt, an alarm signal is generated.


45/109


c2 %auses for "uisance Alarms' 2oor placement is a primary cause of

nuisance alarms. 'ibration sensors may generate alarms if mounted on walls that areexposed to external vibrations $e.g., trains, planes%, or if the walls are subDect to vibrating

machinery. )n any of these or similar situations, vibration sensors should not be used.

62 +ypical Defeat >easures' The system can be defeated by avoiding entry throughthe protected area, or by selecting a point and method of entry in a segment of a wall,

roof or floor that will permit the suppression(diffusion of the intrusion vibrations.

&nother defeat measure, which is also applicable to many other sensors as well, is thegeneration of a persistent but random number of false alarms over a long period of time,

causing the alarm to be ignored or the response time greatly diminished.

SIGNAL CONDUIT

CONTROL UNIT

POWER CONDUIT

$IBRATION SENSORS

ATTEMPTED INTRUSION CAUSES$IBRATIONS IN A REGULARPATTERN.

LOCALPROCESSOR

PROCESSORSIGNAL

PULSECOUNTCIRCUITRY PIE/O ELECTRIC

TRANSDUCER

ALARM CONTACTOUTPUT(S)

$IBRATION

SENSOR

STEEL LATTICE

9A88 #!RA+#0" S$"S0R


46/109



47/109


+$%"080G: R$#$9 E

.#!$R 0P+#% 9A88

2 #ntroduction' & fiber optic wire sensor is in an open mesh network $quilt%

appliquP that can be applied directly to an existing wall or roof, or installed in a wall $or

roof% as it is being constructed. The fiber optic network is designed to detect the lowfrequency energy $vibrations% caused by chopping, sawing, drilling, ramming or physical

attempt to penetrate the structure on which it was mounted.

52 0perating Principle' The fiber optic cable acts as a line sensor and contains an

electro optics unit which transmits light using a =ight 7mitting +iode $=7+% as the light

source. The light travels through the fiber optic network and is picked up by a detector,

which is very sensitive to slight alterations in the transmission. Bhen an adequatealteration in the light pattern takes place, the signal processor generates an alarm.

easures' The system can be bypassed by avoiding entry

through a protected area or targeting an insensitive location as the point of entry.


48/109


IN"WALL $IBRATION FIBER"OPTIC SENSOR

BRICK WALL

PROCESSORBOX

FIBEROPTICCABLE

.#!$R 0P+#% S+R/%+/RA8 #!RA+#0" S$"S0R


49/109


+$%"080G: R$#$9 E

A/D#0 S$"S0RS

2 #ntroduction' &udio detectors listen for noises generated by an intruder’s entry

into a protected area, and are generally used, but not exclusively, in internal applications,

from an entrance foyer to critical data(resource storage areas.

52 0perating Principle' The sensor is made up of two devices? Pick&u$ units

mounted on the walls or ceilings of the monitored area, and an Am$lifier unit whichincludes processing circuitry. The 2ick!up units are basically microphones that listen for

noise. These microphones collect sound for analysis by the processor circuit, which can

be calibrated to a noise threshold that is characteristic for an intrusion attempt. )f a

certain amount of noise is detected from a monitored area within a selected time period,an alarm signal is generated.

easures2 &n intruder who makes a slow, deliberate entry, andtakes measures to muffle the normal sounds of movement and intentionally allows


50/109


sufficient lag time to occur between any noise generated by his movement may avoid

detection.


51/109


+$%"080G: R$#$9 E 4

PASS#$ /8+RAS0"#%

2 #ntroduction' The passive 0ltrasonic sensor is a motion detection device that

Glistens for ultrasonic sound energy in a protected area, and reacts to high frequencies

associated with intrusion attempts.

52 0perating Principle' The $assi(e ultrasonic sensor ElistensE for frequencies that

have a range between easures' 2assive ultrasonic sensors have a limited frequencyspectrum, and intrusion sounds other than those that fall into the unit’s spectrum $such as

drilling%, will not generate an alarm signal. 1or this reason it is recommended that an


52/109


active measures detection device $such as a microwave sensor% be used in conDunction to

ensure adequate detection.

1 FT

,' FT

CEILING MOUNTED

WALL MOUNTED

, FT

2 FT

PASS#$ /8+RAS0"#% >0+#0" S$"S0R


53/109


+$%"080G: R$#$9 E

A%+#$ /8+RAS0"#%

2 #ntroduction' The &ctive 0ltrasonic sensor is a motion detecting device that

emits ultrasonic sound energy into a monitored area and reacts to a change in the reflected

energy pattern.

52 0perating Principle' 0ltrasonic sensors use a technique based on a frequency

shift in reflected energy to detect intruders. 0ltrasonic sound is transmitted from thedevice in the form of energy. The sound uses air as its medium and travels in a wave type

motion. The wave is reflected back from the surroundings in the room(hallway and the

device Ghears a pitch characteristic of the protected environment. Bhen an intruder

enters the room, the wave pattern is disturbed and reflected back more quickly, thusincreasing the pitch and signaling an alarm.

easures'. #low hori@ontal movement by an intruder across the

area of coverage is often difficult for ultrasonic sensors to detect. 2roper calibration is

needed to ensure that slow moving intruders will be detected. )n addition, aknowledgeable and properly equipped intruder can use special Gtest lights to detect

coverage patterns and circumvent these areas.


54/109


TRANSCEI$ER

RX

ALARM CONTACTS

TX

SIGNAL PROCESSOR

LOCAL

PROCESSOR

A%+#$ /8+RAS0"#% >0+#0" S$"S0R


55/109


+$%"080G: R$#$9 E 5

PASS#$ #".RAR$D

2 #ntroduction' &s the name implies, 2assive )nfrared $2)A% sensors are passive,

that is, the sensor does not transmit a signalF the sensor head simply registers an impulse

when received. The sensor head is typically divided into several sectors(@ones, eachdefined with specific boundaries. +etection occurs when an emitting heat source

$thermal energy% crosses two adDacent sector boundaries or crosses the same boundary

twice within a specified time.

52 0perating Principle' 2assive infrared sensors detect electromagnetic radiated

energy generated by sources that produce temperatures below that of visible light. 2)A

sensors do not measure the amount of )A energy per se, but rather the change of thermalradiation. 2)As Gsee(detect infrared Ghot images by sensing the contrast between the

Ghot image and the Gcooler background.

)nfrared energy is measured in microns, with the human body producing energy in

the region of !-6 microns. Most 2)A sensors are focused on this narrow band width. )n

order to avoid capturing environmental thermal deviations, Aate "f hange measurementcircuitry or bi!directional pulse counting circuitry is employed.

)n Aate "f hange measurement, the processor evaluates the speed at which theenergy in the field of view changes. Movement by an intruder in the field of view

produces a very fast rate of change, while gradual temperature fluctuations produce a

slow rate of change. )n the bi!directional pulse counting technique, signals from separate

thermal sensors produce opposite polarity. &n unprotected(unshielded human entering afield of view moving at a typical speed $walk or above% will normally emit(produce

several signals which allow detection to occur.

Bhen the radiation change captured by the lens exceeds a certain pre!set value,

the thermal sensor produces an electrical signal which is sent to a built!in processor for

evaluation and possible alarm.


56/109


"ptics and reflective principles play a very important role in the design and

function of 2)As. *ecause of the need to precisely focus thermal radiation, thereflection(focusing of the energy waves is done two ways? Aeflective 1ocusing and the

1resnel =ens method.

)n Aeflective 1ocusing, the energy waves are reflected off a concave mirror anddirected into the sensing element. *y contrast, a 1resnel =ens allows the energy to travel

directly to the sensor. *oth methods use some type of protective covering on the sensor,

so the loss of some energy is unavoidable. However, both sensors work quite well.


a2 Applications' 2assive infrared sensors should be installed on walls or

ceilings, with the detection pattern covering the possible intrusion @ones. 7ach

detection(surveillance @one can be pictured as a Gsearchlight beam that gradually widens

as the @one extends farther from the sensor with different segments being illuminatedwhile others are Gdark. This design characteristic allows the user to focus the Gbeam on

areas where protection is needed while ignoring other areas, such as known sources of

false alarms. Tower(ceiling mounted 2)As theoretically provide a :/99 detection pattern.

&2 %urtain 8ens .eature' The interchanging of different lens and

reflectors(mirrors permits the field$s% of view and @ones of surveillance to be changedand(or segmented. 2)A design includes a Gurtain =ens feature that provides a full

barrier protection @one by eliminating the typical dead @ones. 2)As with this type are

ideal for protecting hallways or entry points.

c2 %onditions for /nrelia&le Detection' *ecause the 2)A looks for thermal

radiation proDected against a cooler background, detection is based on temperature. &s

the environment approaches the same temperature as the intruder, the detectors becomeless sensitive. This is especially true for environments ranging between 89 ! -99 degrees.

Theoretically, if a person was radiating the same temperature as the environment, he

would be invisible to the sensor. 1or this reason another type of sensor should be used inconDunction with the 2)A to enhance the system. omplementary sensors for interior

applications include balanced magnetic switches, glassbreak detectors, and time delayed

T' cameras. 1or exterior applications 'ideo Motion +etection is a goodcomplement.

d2 %auses for "uisance Alarms' Heat radiating from small animals and (or

rodents can cause false alarms. Time activated space heaters, ovens and hot water pipescan also provide false alarms if they are in the field of view. )n addition, 2)A sensors that

are not designed with the capacity to filter $ignore% visible light can be affected by car

headlights or other sources of focused light. &lthough infrared energy from sunlight isfiltered by ordinary window glass, obDects in a room can become heated over time and

subsequently begin emitting(reflecting infrared energy. )f this energy is Gturned off(on,

$such as by the movement of clouds%, it can create a random Gon(off situation, therebygenerating nuisance alarms.


57/109


?2 +ypical Defeat >easures' #hadowing, cloaking or masking the intruding heatsource $person(machine% from the field of view decreases the probability of detection as it

reduces the possibility of sufficient radiated(emitted heat being focused on the thermal

sensor. )n addition, knowing the dead spots of the detection pattern can permit an

intruder to bypass active regions. Balking into the sensor rather than across the sensor’sfield of view can also reduce the detection capability by not allowing the boundaries of

the detection beams to be broken.

TOP $IEW

!'' " !

SIDE $IEW

FT

'' FT !' FT ! FT 2' FT ,' " !'' FT MAXIMUM2 FT

"2 "!'("

)"("!!

)

'"("!')

THE NUMBER% RANGE% AND PRO3ECTION ANGLES OF THE DETECTION BEAMS $ARY DEPENDING UPON DESIGN.

PASS#$ #".RAR$D S$"S0R


58/109


D#S% .800R !$A>

PA++$R"

+:P#%A8 P#R %0$RAG$ PA++$R"

(%$#8#"G >0/"+$D)

2(*.,+)

,(!'.1+)

1(2.+)

!2(,.+)

SIDE $IEW TOP $IEW

+:P#%A8 P#R %/R+A#" D$+$%+#0" PA++$R" (9A88 >0/"+$D)

* " 2' FT MAX HEIGHT

2' " FT MAX

DISTANCE

, " . FT MAX WIDTH

,"D $IEW


59/109


SENSOR

MOST SENSITI$E TO MOTION

ACROSS FIELD OF $IEW

PASS#$ #".RAR$D

LARGE ROOM CORRIDOR

SMALL ROOM

P#R %0$RAG$CP8A%$>$"+ PA++$R"S


60/109


+$%"080G: R$#$9 E <

#"+$R#0R A%+#$ #".RAR$D

2 #ntroduction' )nterior active infrared sensors generate a curtain pattern of modulated infrared energy and react to a change in the modulation of the frequency or an

interruption in the received energy. *oth of these occurrences happen when an intruder

passes through the protection @one.

52 0perating Principle' )nterior active infrared sensors are made up of a

transmitter and receiver encased within a single housing unit. The transmitter uses a laser to create a detection @one. The laser plane is proDected onto a special retro!reflective tape

that defines the end(edge of the protection @one. 7nergy is reflected off the tape back to

the receiver, which is located in the same housing unit as the transmitter. 0pon reaching

the receiver the energy passes through a collecting lens that focuses the energy onto acollecting cell, which converts the infrared energy to an electrical signal. The receiver

monitors the electrical signal and generates an alarm when the signal drops below a

preset threshold for a specific period of time. &n intruder passing through the field of detection will interrupt the signal and temporarily cause the signal to fall below the

threshold value.

easures' &voidance of the proDected laser plane. &

knowledgeable intruder can deduce the field of the potential detection pattern from thelocation of reflective tape, and plan his movements to avoid detection.


61/109


CHANNEL A

CHANNEL B

CHANNEL C

CHANNEL E

CHANNEL D

R$%$#$R S#G"A8

S+R$"G+ GRAP

+ransmitCReceive

Reflector

A%+#$ #".RAR$D >0+#0" S$"S0R

#"+R/S#0" #S D$+$%+$D !:

RAP#D, S/S+A#"$D

R$D/%+#0" #" R$%$#$D

S#G"A8S 0" A "/>!$R 0.

R$%$#$R %A""$8S.


62/109


+$%"080G: R$#$9 E 6

$B+$R#0R A%+#$ #".RAR$D

2 #ntroduction' &ctive infrared sensors generate a multiple beam pattern of

modulated infrared energy and react to a change in the modulation of the frequency, or an

interruption in the received energy. *oth of these occurrences happen when an intruder passes through the area covered by the beams.

52 0perating Principle2 &n active infrared sensor system is made up of two basicunits, a transmitter and a receiver. "ne of the units is located at one end of the protection

@one and the other at the opposite end of the @one. The transmitter generates a multiple

frequency straight line beam to the remote receiving unit, creating an infrared Gfence

between the transmitter and the receiver. 7nergy reaching the receiver passes through acollecting lens that focuses the energy into a collecting cell, which converts the infrared

energy to an electrical signal. The receiving unit monitors the electrical signal and

generates an alarm when the signal drops below a preset threshold for a specific period of time. &n intruder passing through the field of detection will interrupt the signal and

temporarily cause the signal to fall below the threshold value.


63/109


reliable detecting range. )n areas where conditions like these are routine, another type of

device should be considered, or the detection @one should be decreased to compensate for energy reduction.

c2 %auses for "uisance Alarms' MaDor causes of nuisance alarms are those

that involve animal interaction with the protected area. 'egetation also can pose a problem if allowed to grow to a si@e its movement $caused by windy conditions% will

generate an alarm.

62 +ypical Defeat >easures' #ince active infrared detectors are line of sight

devices, the most common method of defeat is bridging(tunneling under the detection

beams. 1or this reason it is recommended that any dips or gullies between the transmitter and receiver units(columns be filled in to make the area uniformly level. &nother typical

defeat measure is to use the Tx and Ax columns for support to vault over the detection

beams. This can be prevented by overlapping the beam detection @ones.

CHANNEL A

CHANNEL B

CHANNEL C

CHANNEL E

CHANNEL D

RECEI$ER SIGNALSTRENGTH GRAPH

TRANSMIT

RECEI$E

A%+#$ #".RAR$D >0+#0" S$"S0R

INTRUSION IS DETECTED

BY RAPID% SUSTAINED

REDUCTION IN

RECEI$ED SIGNALS ON A

NUMBER OF RECEI$ER

CHANNELS.


64/109


+$%"080G: R$#$9 E ?

D/A81+$%"080G: PASS#$ #".RAR$D C >#%R09A$

2 #ntroduction' +ual!Technology 2assive )nfrared(Microwave sensors use acombination of both microwave and passive infrared technology in combination with

A'D logic to provide a lower 1alse &larm Aate $1&A% sensor than either of the sensors

independently. This category of sensors are typically referred to as +ual!Tech.

52 0perating Principle2 )n this type +ual!Technology sensor, a passive sensor

$2)A% and an active sensor $Microwave% are combined into one unit. *oth sensingelements are located in a single casing, and are connected electronically by using the

A'D =ogic function. The areas of coverage for each sensor are similar in shape so the

detection @one is uniform. #ince the two sensors will not Gsense an intrusion detection

precisely at the same instant, the system is designed to generate an alarm when bothsensors produce an output in a pre!selected time interval. >"T7? The technical

parameters and operating characteristics of each sensor are described in previous reviews

$Tabs / and -


65/109


can be both cost effective $cheaper than purchasing two individual sensors% and 1&A

beneficial if employed in a predictable and(or controlled environment.

c2 %auses for "uisance Alarms' >uisance &larm Aate for the dual

technology sensor is very low, however, a combination of environmental conditions $e.g.

fluorescent lights, heater exhaust% may cause false detection. 7nvironmental conditionsthat affect each sensor individually should be considered $compensated for% to keep from

reducing effectiveness of the dual technology unit.

62 +ypical Defeat >easures2 5nowledge of the dead spots in the detection pattern

will permit an intruder to bypass all active regions. #hort of this knowledge, extreme

slow motion movement is difficult for microwave sensors to detect, and blocking or masking the infrared sensor’s field of view can further decrease its sensitivity and reduce

the probability of sufficient Gheat being detected by(focused on the 2)A portion of the

sensor. )n addition, walking into the 2)A sensor, rather than across its field of view, can

reduce the detection capability of the sensor by not Gbreaking the boundaries of the 2)A detection beams.


66/109


+$%"080G: R$#$9 E @

.$"%$ #!RA+#0"

2 #ntroduction' 1ence vibration sensors mounted on fence fabric detect frequency

disturbances associated with sawing, cutting, climbing or lifting of the fence fabric.

52 0perating Principle' &ll of these type actions generate mechanical vibrations

and(or stress in the fence fabric that are different from the vibrations associated with

normal or natural occurring environmental activity, and typically have higher frequenciesand larger amplitudes. 1ence vibration sensors detect these vibrations by using either

electro!mechanical or pie@oelectric transducers. #ignals from the transducers are sent to

the signal processor to be analy@ed. 0pon arriving at the processor, frequencies

uncharacteristic of intrusion are filtered out. 1requencies characteristic of intrusion are passed through the screening filter, thus triggering an alarm.


67/109


&2 Pieoelectric Sensors' 2ie@oelectric sensors convert the mechanical

impact forces generated during an intrusion attempt into electrical signals. 0nlike theopen(close signal generated by electro!mechanical sensors, pie@oelectric sensors generate

an analog signal that varies proportionally in amplitude and frequency to the vibration

activity on the fence fabric. These signals are sent to the signal processor for evaluation,

where they first pass through a filter that screens out signals uncharacteristic of intrusions. The signal processor then interprets the remaining signals to determine if

sufficient activity has occurred to warrant an alarm.


a2 Applications' 1ence vibration sensors perform best when mounteddirectly to the fence fabric. 7ach sensor is connected in series along the fence with a

common cable to form a single @one of protection. The sensor @one lengths have a

recommended range of :99 feet.

'ibration sensors are the most economical fence sensor and the easiest to install.

The sensors have a high probability of detecting intrusion and work well protecting

properly installed and maintained fence lines.

)n!ground vibration $seismic% sensors installed adDacent to the perimeter fence $in

a controlled @one within the overall protected area% can provide additional detectioncapability protection in case the vibration sensors mounted on the fence are bypassed by

tunneling or careful climbing.

&nother type of enhancement focuses on adding information about the prevailing

weather conditions to increase or decrease the sensitivity of the processor. & weather

sensor station can be mounted on the fence line to feed information to a field processor.

The field processor then adDusts vibration alarm sensitivity based on inputs from theweather station to ensure an effective sensitivity range is maintained.

Mounting volumetric motion detection devices $microwave, active infrared% alongthe perimeter of the fence will also enhance detection reliability. +etermining which

volumetric $area monitoring% device to use will depend greatly on the environment,

terrain and length of the fence line.

*ecause vibration sensors are prone to activation from all types of vibrations,

additional sensing equipment is frequently added to the processor capability to reduce

false activations. "ne type of enhancement is the pulse count accumulator circuit. Biththis device, sensitivity is determined by a number of EpulsesE required to create an alarm.

& pulse is a specific amplitude of activity occurring due to fence stress or vibration

associated with cutting chain links or climbing the fence fabric. & minimum number of pulses is required during a preset period of time before an alarm is generated.

&2 %onditions for /nrelia&le Detection' 2roper installation and spacing of

sensors is critical to reliable detection. 2oor quality fences with loose fabric can create


68/109


too much background activity $flexing, sagging, swaying%, initially generating false

alarms and eventually transmitting little reliable intrusion activity. =ikewise, adverseweather conditions can cause sensitivity settings above(below what is required for

reliable detection to occur. 1ence corners pose particular challenges for readily detecting

intrusion vibrations, because of the increased bracing of the fence posts and more solid

foundations typically used at a corner or turn!point.

c2 %auses for "uisance Alarms' #hrubbery and tree branches as well as

animals and severe weather that come in contact with the fence can cause the fence tovibrate, triggering the sensors to react. In areas !ith high !ind or numerous animal

interactions !ith the fence line* (ibration sensors should not be used+ 'ibration sensors

should only be used in areas(circumstances where natural or man!made environmentalvibrations are minimal or non!existent. 'ibration sensors are not satisfactory nor are they

reliable in areas(situations where high vibrations are likely to be encountered, such as in

close proximity to construction sites, railroad tracks(yards or highway and roadway

activity.

?2 +ypical Defeat >easures' The most common defeat method is to avoid

contact with the fence by bridging it. "verhanging trees and structures can assist theintruder in this regard. #imilarly, cars, buses, trucks, equipment or storage containers

positioned(parked next to the fence can serve as platforms for Dumping(bridging the

fence. &lthough less common, deep tunneling, if accomplished without contacting thefence supports, will allow an intruder to bypass a fence mounted vibration sensor system.


69/109


X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

XX

XX

XX

X

X

X

XX

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

CONDUIT

SENSOR

3UNCTION BOX

CONDUIT

FREE"FLOATING CONTACT MO$ES

SLIGHTLY FROM MECHANICAL SHOCK

CAUSED BY INTRUDER MO$EMENT

(CLIMBING% CUTTING% LIFTING) CON$ERTS

MECHANICAL SHOCK TO ELECTRIC PULSES.

STATIONARY SWITCH CONTACTS

X

X

X

#!RA+#0" .$"%$ S$"S0R


70/109


+$%"080G: R$#$9 E *

$8$%+R#% .#$8D

2 #ntroduction' 7lectric field sensors generate an electrostatic field

between(around an array of wire conductors and an electrical ground. #ensors in the

system detect changes or distortion in the field. This can be caused by anyoneapproaching or touching the fence.

52 Principle of 0peration' The 7!field sensor consists of an alternating currentfield generator which excites a field wire $two or more sensing wires%, around which an

electro!static field is created and an amplifier signal processor which detects changes in

the signal amplitude of the sensing wires. The alternating current on the field wire

creates an electrostatic field in the air between the field wire to ground. Bhen an intruder enters the Gfield, large amounts of the electric charge flow through the intruder due to

the human body disrupting the field. The processor detects this change and generates an

alarm.

To reduce false alarms, the signal goes through a filter which reDects high

frequencies caused by wind vibration and low frequencies caused by obDects striking thefence wires. However, the filter allows frequencies associated with intrusion

characteristics to continue to the processor. &t the processor, three conditions must be

met to signal an alarm? the signal amplitude must exceed a preset value that discriminatessmall animals, the frequency must be in a range that is associated with humans, and the

signal must persist for a set period of time. "nce these conditions are met, the processor

signals an alarm.

uisance &larm

Aate. )n some cases bridging and tunneling can be detected, depending on how close the

disturbance activity is to the sensor. #ensor @one length can extend up to -;99 feet. The7!field sensor should be considered if bridging or tunneling are expected intrusion

tactics. "ther fence sensors $vibration, taut wire% can be added to provide a higher level

of detection probability.


71/109


&2 %onditions for /nrelia&le Detection' &dverse weather conditions such

as rain and snow can create problems, as can lightening storms. )n addition, vegetationand animal movement along the fence line can cause the sensors to react. =arge spacing

between wires should be avoided, as it is possible to move between the wires without

causing an alarm if sufficient space exists.

"0+$? &lthough 7lectronic Magnetic )nterference $7M)% is not normally a maDor factor,

interference difficulties can arise in situations where multiple systems are deployed in a

congested area, unless different frequencies are used by each sensor.

c2 %auses for "uisance Alarms' &nything causing excessive fence

vibration such as weather, birds, and animals will contribute to nuisance alarms."vergrown vegetation coming in contact with the fence line can also be a problem and

should be avoided by keeping grass and shrubbery clear of the fence.

62 +ypical Defeat >easures' &lthough electric field sensors provide some meansof detecting underground intrusion activity because of disturbances in the electric field,

the sensor field can be bypassed by deep tunneling $/ feet or more% or bridging over the

fence.


72/109


X

X

X X

X

X

THREE"WIRE SENSOR FOUR"WIRE SENSOR

FENCEFENCE

ELECTRIC FIELD SENSOR

$8$%+R#% .#$8D D$+$%+#0" %0".#G/RA+#0"CPA++$R"S

4 4

4

S

S

S

S

4 0 FIELD WA$ES

S 0 SENSE WA$E


73/109


+$%"080G: R$#$9 E

%APA%#+A"%$

2 #ntroduction' apacitance sensors detect changes in an electrostatic field created

by an array of wires. & signal is generated when an intruder changes the capacitance of

the field by approaching or contacting the wires.

52 0perating Principle' apacitance sensors consisting of three closely spaced

wires are arrayed and installed on the top of a fence. & low voltage signal is induced inthe wire array creating an electrical field with the fence serving as the electrical ground.

& sensor processor continually measures the differential capacitance between the sensing

wires and ground.

"nce a change in the signal is detected at the processor, a filter screens th

perimeter security sensor technology

Documents