ASIS CPP - Physical Security (Part 1) Flashcards
1
Q
CPTED
8 Main categories of Physical Security Measures
A
- CPTED (Crime-Prevention Through Environmental Design
- Physical barriers & site hardening
- Physical entry & access control
- Security Lighting
- Intrusion Detection
- Video Surveillance
- Security Personnel
- Security policies & procedures
2
Q
CPTED
What can lead to a reduction in the opportunity fear & incidence of predatory, stranger-to-stranger type crime?
A
Proper design & effective use of the built environment
3
Q
CPTED
Should be divided into smaller, more clearly defined areas or zones (defensible space, per Oscar Newman)
A
4
Q
CPTED
What can also result in an improvement of the quality of life - how & where we live, work, & play?
A
CPTED
5
Q
CPTED
CPTED should be integrated into…?
A
The design & function of the buildings or location
6
Q
CPTED
All Human Space…
A
Has some designated purpose
Has social, cultural, legal or physical definitions that prescribe the desired & acceptable behaviors
Is designed to support & control the desired & acceptable behaviors
7
Q
CPTED
CPTED is the design or redesign of a venue to reduce crime opportunity & fear of crime through?
A
Natural Means
Mechanical Means
Procedural (organizational) means
8
Q
CPTED
At its core, CPTED is based on common sense & a heightened awareness about how people use their space for legitimate & criminal intentions
A
9
Q
CPTED
3 Classes of CPTED Strategies
A
- Mechanical measures
- Organizational measures
- Natural or architectural measures
10
Q
CPTED Strategies
A
Natural access control
Natural surveillance
Natural territorial reinforcement
Management & maintenance
Legitimate activity support
Compartmentalization
11
Q
CPTED
Methods for implementing CPTED
A
Organized methods (staffing)
Mechanical methods (technical products)
Natural methods (site planning, design, landscaping, signage)
12
Q
CPTED
Once the first window is broken, vandalism and/or other crime quietly follow if it is not prepared
A
Broken Window Theory
13
Q
CPTED
CPTED is congruent with the 3 D’s
A
Deterring
Detecting
Delaying aggressors
14
Q
CPTED
Preventing crime & losses is inherent in many human functions behaviors & activities
A
15
Q
CPTED
CPTED security standards focus on 4 categories
A
- Perimeter & exterior security
- Entry security
- Interior security
- Security planning
16
Q
CPTED
Types of CPTED Security Zones
A
- Unrestricted zones
- Controlled zones - authorized personnel in these general areas
- Restricted zones - authorized personnel in these specific areas
17
Q
CPTED
Deterrence is achieved through…?
A
Measures that potential adversaries perceive as too difficult to defeat
18
Q
CPTED
For the security professional, CPTED is a set of management tools targeting…?
A
Places
Behavior
Design & Use of Space
19
Q
CPTED
What is more cost-effective than making changes after construction starts
A
Integrating CPTED during the initial planning
20
Q
CPTED
Whenever possible, security planning should begin during…?
A
Site Selection
21
Q
CPTED
CPTED is intended to be integrated throughout the construction process
A
Programming
Schematic Design (SD)
Design Development (DD)
Construction documents or working drawings (CD)
Bids for construction & selection of contractor (RFP)
Security needs should be addressed int he programming phase
22
Q
CPTED
Establish a secure perimeter around the building as far out as possible… setbacks how far?
A
100 ft. is suggested
23
Q
CPTED
Where should you position concrete flower planters etc…?
A
Near curbs less than 4 ft between them to block cars
24
Q
CPTED
Locate parking as far from the building as practical & place it within view of occupied rooms or facilities
A
25
CPTED
Landscaping Considerations
Low growing plants should be set back 1 yard from the edge of paths or walkways
Low-growing shrubs should be kept no higher than 32" in height
Tree canopies should be trimmed up to 8' to provide a clear line of the site & reduce hiding spots
26
CPTED
Parking garages should be equipped with what?
## Footnote
- 3 ft. or higher shrubs/trees should be 10-15 ft. from the structure
- Booths should have 360 degrees visibility & a means of communication
- No public restrooms but should be within view of the booth
- One vehicle entry/exit should be used if possible (based on traffic volume)
- Open-walled, upper levels to allow natural surveillance & permit hearing of calls for help
- Egress only exterior pedestrian doors
27
CPTED
Parking Garages (ctd...)
## Footnote
- Potholes in solid walls for visibility
- Stairwells & elevators in a central location visible from both
- Stairwells visible from exterior & offering no hiding place & no roof access
- Elevators with glass for exterior visibility along the exterior of the facility
- Access only to the lobby from the garage elevators or stairs
- Adequate lighting
28
Access Control
Refers to the process of managing databases or other records & determining the parameters of authorized entry, such as who or what will be granted access when they may enter where access will occur
Access Control
29
Access Control
Categories of Access Control
Manual
Machine Aided
Automated
30
Access Control
Types of attacks used to defeat access controls
Deceit
Direct Physical Attack
Technical Attack
31
Entry Control
An entry control subsystem includes the following performance measures...
Throughout
Error Rates
32
Entry Control
An Entry Control Subsystem
- is not an access control system
- Is part of the detection system
- Allows the movement of authorized personnel & material into & out of facilities
- Detects & possibly delays movement of unauthorized personnel & contraband
- Refers to the physical equipment used to control the movement of people or material into an area
33
Entry Control
Objections of an entry control system used for physical protection are...
- To permit authorized persons to enter & exit
- To detect & prevent the entry or exit of contraband material (weapons, explosions, unauthorized tools, or critical assets)
- To provide information to security personnel to facilitate assessment & response
34
Entry Control
Verification of authorization of personnel to enter a controlled area is usually based on...
1. Carrying a valid credential (what you have)
2. Knowing a valid PIN (what you know)
3. Possessing the proper, unique physical characteristics on file (who you are)
35
Badge Technologies
Magnetic Stripe ("mag stripe")
- Widely used in commercial credit/debit cards
- Low-coercivity ("LoCo") cards are 300 oersteds; easy to erase; typical of credit/debit cards
- High-coercivity (Hi - CO) cards are 2500 to 4000 oersteds; hard to erase, but can be done with rare\_earth magnets; typical of company badges
- Easily forged, duplicated (can use proprietary encoding schemes but not common)
36
Access & Entry Control
Badge Technologies
- Magnetic Stripe
- Bar Code
- Proximity
- Smart Card
37
Access/Entry Control
Badge Technologies Proximity...
- Small RF transponder/transmitter is powered by an **onboard battery (active)** or it is energized by the **card reader (passive)**
**-** Low-frequency badges are in the **125 KHz range**
- High-frequency badges range from **2.5 MHz to over 1 GHz**
38
Access/Entry Control
Badge Technologies - Smart Card
- Gold contacts on the surface of the card allow for communication with a reading device
- Contactless smart cards use RF communications & do not have the gold contacts
- Main advantages: Large memory & its high degree of resistance to forgery or compromise
- Ability to encrypt communications
- Can be prohibitively expensive
- Homeland Defense Presidential Directive (HSPD 12)
39
Access/Entry Control
Personal Identity Verification System
Biometrics
- Corroborate claimed identities on the basis of one or more unique physical biometric characteristics of the individual
- Can differentiate between: **_verification & recognition_**
40
Access/Entry Control
Personal identify verification systems
All personal identity verification systems consider 3 things
- The uniqueness of the feature used for identification
- The variability of the characteristic
- The difficulty of implementing the system that processes the characteristic
41
Personal identity verification systems
Type 1 error rate:
False rejection of a valid user
42
Personal identity verification systems
Type II Error rate
False acceptance of an invalid user
43
Access/Entry Control
Personal identity verification systems
**Equal error rate**
- **Cross-over point where Type 1 & Type 2 errors are equal**
**- Not necessarily the point at which the device should be operated**
**- Not the lowest point for either type of error**
44
Access/Entry Control
Personal identity verification systems
**Finger Prints**
- Still considered one of the most reliable means of distinguishing one individual from another
- Most systems use image processing & pattern recognition
**Minutia points**
**Ridge endings**
**Bifurcations**
45
Access/Entry Control
Personal identity verification systems
**Hand/Finger Geometry**
- Characterizes the shape of the hand
- Measures 3-dimensional features of the hand such as the widths & lengths & the thickness of the hand
46
Personal Identity Verification System
Eye Pattern
- Imaging of iris by a video camera
- Operates in the recognition mode
- 10 - 12" read distance (no physical contact)
- 2% of population cannot be enrolled due to blindness or other eye issues
47
Personal identity verification system
**Face**
**- Utilize distinguishing characteristics of the face**
**- Captured with** **video** **camera or thermal image**
48
Personal identity verification system
Voice
- Speech measurements: waveform envelope, voice pitch period, relative amplitude spectrum, resonant frequencies of the vocal tract
- Low security, easily deployed, more public acceptance (low distrust)
49
Personal identity verification system
Handwriting
- Used for many years by the bank
- Signatures can be easily forged
- Handwriting dynamics include displacement velocity & acceleration
50
Access/Entry Control
Access control barriers include...
Doors
Gates
Turnstiles
Elevators
51
Access/Entry Control
Vehicle access controls are...
Manual
Electronic
52
Access/Entry Control
Electro-Mechanical Lock Types
- Electric deadbolts
- Electric latch
- Electric strike
- Electric lockset
- Exit device
- Electromagnetic lock
53
Access/Entry Control
Device unlocks upon loss of power (but may stay latched - "positive latching")
Fail Safe
54
Access/Entry Control
Device locks upon loss of power
Fail Secure
55
Access/Entry Control
Single action / motion egress
One action/motion required to release door to exit
56
Alarm Communications & Display (AC&D)
The part of a PPS that transports alarm & assessment information to a central point & presents the information to a human operator
AC&D: Alarm Communication & Display
57
The most important measure of AC&D Effectiveness?
How well it quickly & clearly communicates alarm data from sensors to the system
58
AC&D
Two critical elements of alarm communication & display
- **Transportation or communication of data**
**- Presentation or display of that data to a human operator in a meaningful manner**
59
AC&D
When an alarm occurs, the AC&D system must communicate to the operator the following information
**- When an alarm has occurred**
**- What or who caused the alarm**
**- When the alarm happened**
60
AC&D
Security communications require the following assurances
**- The integrity of the communications medium (availability of the message path)**
**- The integrity of the message (complete & errorless transmission of the data)**
**- Timeliness of the transmission (data communication within an appropriate time frame)**
**- Message security (accessibility of the communication to authorized persons only)**
61
AC&D
Communications Security - Line Protection
**- Outside lines should be installed underground**
**- Inside wiring should be encased in conduit**
62
AC&D
Communication Security - Line Supervision
**Simplest line supervision:** End-of-line (EOC) resister (detects open circuit, ground, wire-to-wire short)
63
AC&D
Communication Security - Scramblers
- Disguise interceptible communications
- 2 characteristics of voice that can be scrambled
frequency (pitch of voice) (most typically scrambled)
Amplitude (loudness)
64
AC&D
**Transmission of Alarm Signals**
Alarm signals may be transmitted on an unshielded pair of direct current (DC) Conductors
65
AC&D
Signals also may be transmitted on...
Lines installed to carry electric power
66
AC&D
Optical Fiber
**A strand of high-purity, spun glass, typically about the thickness of a human hair**
67
AC&D
Optical fibers can be used to carry...
**- Voice-grade signals**
**- Video signals**
**- Digital or data grade signals**
68
AC&D
Optical fibers differ from a conventional metal wire in several ways
- Not affected by (EMI) or (RFI)
- Don't carry electrical current nor radiate signals
- Can carry many more multiplexed messages
- Much smaller & lighter than conventional
- Flexible & can take an irregular course from P to P
- Not vulnerable to interception by acoustical or inductive coupling
69
AC&D
Optical Fiber
Optical fiber is less expensive than copper
70
AC&D
Video Transmission Methods
## Footnote
**Coaxial Cable**
**Telephone Lines**
**Optical Fiber**
**Dedicated Twisted Pair**
**DC Wire**
71
AC&D
Video Transmission Methods
No processing required if transmission distance is short enough, typically 1,000 ft.
72
Video Transmission Methods
The transmission distance without amplification is 1 mile or more
Optical Fiber
73
AC&D
Good performance can be achieved at wire distances of up to 4,000 ft.
Dedicated Twisted Pair
74
AC&D
Video signals cannot be transmitted directly on DC lines
DC Wire
75
AC&D
3 Types of line transmission used in electronic protection systems
Loop
Point-to-Point
Multi-plexed
76
AC&D
Two methods used to separate multiplexed signals
- Time division multiplexing (TDM)
- Frequency division multiplexing (FDM)
77
AC&D
A wireless communication requires
- A transmitter to furnish radio frequency energy
- An antenna to radiate the energy into the atmosphere
- A receiver
- Power for the transmitter & receiver
78
AC&D
Wireless Transmission
Any unscrambled or unencrypted communication transmitted by wireless technology should be considered available for interception
79
AC&D
Voice radio (2-way radio) cost & power are determined by
- The distance required to communicate
- Barriers in the transmission path
- Signal interference in the area
80
AC&D
Microwave Transmission
**- Operates between 30 - 300 GHz**
**- Requires microwave generator, power, amplifier, modulation, antenna**
**- One-way & two-way communications**
**- Often require FCC licenses**
**- Penetrates rain, fog, snow & man-made noise**
**- Used in television, multiplexed telephone, multiplexed alarm & high-speed data transmissions**
**- Line-of-sight (LOS) required**
81
AC&D
Laser Communication
**- Light amplification by stimulated emission of radiation (LASER)**
**- Laser light is modulated at a very rapid rate**
**- A photo-detector at the receiver demodulates the laser**
**- Virtually impossible to intercept without detection**
**- A 4-mile transmission line of sight**
**- Reflected can be used but the resolution is reduced**
**- interference from snow, fog, and rain**
**- No FCC license required**
82
AC&D
Most common causes of wireless interference
**- Signals from other transmitters**
**- Industrial & atmosphere noise**
83
Intrusion Detection
The process of detecting a person or vehicle attempting to gain unauthorized entry into an area
Intrusion Detection
84
Intrusion Detection
Considerations for intrusion detection systems
## Footnote
**- Should meet security needs of the facility**
**- Should operate in harmony with other systems**
**- Should not interfere with business operations**
**- Should be cost effective**
85
Intrusion Detection
Basic building blocks of an intrusion detection systems
Sensors
86
Intrusion Detection
Detection criteria for a sensor or sensor system includes
## Footnote
**- What will be detected**
**- What actions are expected**
**- Weight or speed of movement**
**- Probability of detection required**
87
Intrusion Detection
3 main characteristics of intrusion sensor performance are...
**-** **Probability** **of detection (PD)**
**- Nuisance Alarm Rate (NAR)**
**- Vulnerability to Defeat**
88
Intrusion Detection
If the sensor is inappropriate for the operating environment or threat, or not installed, operated, maintained & tested properly, the output of an entire system, is severely limited, becoming a greater burden than a benefit - sensor selection must match the application & environment
89
Intrusion Detection
Probability of Detection
- Perfect is a "1" - reality is always less than "1"
- Confidence Level (CL) is often described in conjunction with PD - unstated CL implies a 90% or better confidence level
- PD is always conditional
- PD also varies by the sophistication of threat
- When high PD is required at all times & all weather conditions, use of multiple sensors
90
Intrusion Detection
Probability of Detection
PD depends primarily on these facts:
- Target to be detected (walk, crawl, tunneling etc...)
- Sensor hardware design
- Installation conditions
- Sensitivity adjustment
- Weather conditions
- Condition of the equipment
91
Intrusion Detection
A nuisance alarm is any alarm not caused by an intrusion
- The NAR identifies the number of nuisance alarms over a given period (ideally zero, but not realistic)
- Alarm assessment is needed to preserve manpower without assessment, detection is incomplete
- Natural causes: vegetation, wildlife, weather conditions, etc...
- Industrial causes: ground vibration, debris moved by wind, electromagnetic interference, etc..
92
Intrusion Detection
A **_false alarm_** is a nuisance alarm generated by the equipment itself
- Acceptable false alarm rate (FAR) should also be specified
- Poor design inadequate maintenance or component failure
93
Intrusion Detection
Vulnerability to Defeat
- All sensors can be defeated
- The objective is **to make the system very difficult to defeat**
- Two general ways to defeat the system
**Bypass: going around the detection**
**Spoof: passing through sensor's normal detection zone without generating the alarm**
94
Intrusion Detection
Occurrence of a potential intrusion event...
Intrusion
95
A change in the condition being monitored
State
96
Intrusion Detection
Loss of electrical power: or failure of the sensor itself
Fault Event
97
Intrusion Detection
Opening, shorting, or grounding of the device circuitry, the enclosure of control panels
Tamper
98
Intrusion Detection
Five ways of classifying intrusion sensors
1. Passive or active (interior & exterior)
2. Covert or overt (interior & exterior)
3. LOS or Terrah following (exterior only)
4. Volumetric or line detection (point) (interior & exterior)
5. Application (interior & exterior)
99
Intrusion Detection
Two types of passive sensors
1. Detect target-generated mechanical energy (walking climbing vibration)
2. Detect target-emitted energy in a natural field of energy (heat, sound, magnetic field etc...)
100
Passive Sensors
- Sensors are harder to locate by aggressors because they do not emit energy
- Safer to use in an explosive environment
- Passive infrared, mechanical activity (walking climbing) vibration etc...
101
Active Sensors
- Transmit energy & detect changes to it
- Includes transmitter & receiver (bi-static)
- Create fewer nuisance alarms
- Microwave, infrared, RF etc..
102
Separate Transmitter & Receiver
Bistatic
103
Transmitter & Receiver are Combined
Monostatic
104
Detect interruption at a fixed, or volume of space
Volumetric Sensors
105
Detect intrusion at a specific point or alarm time
Line or Point Sensors
106
Intrusion Detection
Types of motion detectors
Microwave
PIR
Dual Technology
Ultrasonic
Beam Detectors
107
Intrusion Detection
Video Motion Detectors (VMD)
- Passive, covert, line-of-sight
- Exterior or interior applications
- Sufficient lighting & resolution required
- Nuisance alarms can be plentiful - flickering lights, vegetation movement, animals, rain, camera noise
- Analytics improve NAR
- Digital is more sophisticated but analog is less expensive
- Most VMDs susceptible to very slow movement
108
VMD
Video Motion Detection is based on pixel changes
- Changes in brightness or contrast
- Local movement across adjacent cells
- The speed of motion across all cells
- Size of objects within cells
- Global changes across most or all cells
109
Wireless Sensors
**Operate in the 300 MHz or 900 MHz bands**
110
Issues with wireless sensors include
## Footnote
**- Collisions: multiple messages received at the same time causing none to be read**
**- Fading: degradation of the signal due to distance**
**- Interference: other signals overpowering the sensor's signals**
111
Line supervision techniques
- Reverse polarity
- Sound monitoring
- Radio class C
- Steady direct current class B
- Tone
- Digital classes A & AB
112
Exterior application sensors are divided into 3 categories
Buried Line
Fence-associated
Free Standing
113
Exterior perimeter intrusion sensors
- Typically used by government, nuclear, & correctional facilities
- Ported coaxial cables
- Fence disturbance sensors
- Sensor fences
- Electric field or capacitance
- Bistatic microwave sensors
- Exterior video motion detectors (VMDs)
114
Ported Coaxial Cables
**- "Leaky Coax"**
**- Active, covert, terrain-following**
**- Buried underground**
**- Respond to objects with high dielectric constant or high conductivity (humans, vehicles, etc)**
**-** **Outer** **jacket of** **cable** **is "ported" to allow the signal to leak out**
**-** **Range** **is 1.5 to 3 ft above the surface & about 3 - 6 ft wider than the cable separation**
**- Nuisance alarms sources include metals, water, utility lines, large quantities of salt or metals in soil**
115
Fence Disturbance Sensors
- Passive visible terrain-following
- Attached to fence
- Detect motion or shock
- One of several technologies: fiber-optic, strain-sensing vibration-sensing
- Nuisance alarm sources are common, including wind rain/hail, nearby vibrations
- Can be defeated by crossing over the fence w/o touching it or tunneling under
- **Fence posts should flex/move no more than .5" against a 50 lb.** **force** **at 5 ft height**
**-** Fence fabric should flex/move no more than 2.5" against a 30 lb. force centered between posts
116
Sensor Fences
- Passive, visible, terrain-following
- Sensor cables form the fence itself
- Horizontal-stretched high tension wires at 4" or less apart
- Includes taut-wire fences
- Designed to detect climbing, separation of wires or cutting
- Less susceptible to nuisance alarms - requires about 25 lbs. of force to activate the alarm
- Can be defeated by crossing over the fence w/o touching it, or tunneling under the fence
117
Electric field or capacitance sensors
- Active, visible, terrain-following
- Detects change in "capacitive-coupling" in wires isolated from the fence itself
- Range can extend to 3.3 ft (more nuisance alarms)
- Susceptible to lightning, rain, small animals, motion of the fence itself
- Requires good electrical grounding
- Less susceptible to crossing over or tunneling under fence
118
Free-Standing Infrared Sensors
- Active, visible, line-of-sight, free standing
- .9 micron wavelengths - invisible to the human eye
- Beam is transmitted through a "collimating" lens & received by a "collecting" lens
- Multiple beams required for higher security applications (typically a 2" x 6" detection range)
- Nuisance alarm sources include snow, fog, dust, vegetation, etc...
119
Bistatic Microwave Sensors
- active, visible, line-of-sight, freestanding
- 10 GHz or 24 GHz spectrum
- "Vector Sum": Direct & reflected microwave energy received by the receiver
- Susceptible to crawling or rolling under beam if the ground is not very flat or distance between antennae is more than 120 yds.
Offset Distance: zone of no detection about 10 yds. out from the transmitting antenna - requires overlapping zones of 20 yds
120
Bistatic Microwave Sensors (Ctd..)
- Sensor bed surface is composed of 4" of 1.5" or smaller gravel to eliminate nuisance alarms from standing water
- The largest detection zone is midway between sensors - approximately 4 yds wide x 3 yds high
- Nuisance alarm sources include vegetation higher than 1-2", loose chain link fabric, heavy snow
121
Exterior, perimeter intrusion sensors
Perimeter detection systems should use **_protection-in-dept philosophies,**_ relying on _**two or more simultaneous lines of detection_,** especially in high-security facilities
122
Exterior, perimeter intrusion sensors
Complimentary sensors may also be considered to increase the effectiveness of a sensor deployment
- each sensor brings its own strengths & weaknesses to the overall security plan - complementary sensors do not have the same nuisance sources & probability of detection under each possible scenario
- Sensors should be prioritized for assessment purposes - higher PD sensors have first priority
- Configuration of multiple sensors should be arranged to provide overlapping coverage AND separate lines of coverage
123
Exterior, perimeter intrusion sensors
Sensor combinations operate in two ways
1. OR basis: Either sensors trigger the alarm high PD, higher NAR
2. AND basis: Both sensors are required to trigger the alarm, lower PD, lower NAR
124
Perimeter-in-depth philosophies
Clear zones bounded by fences on both sides are preferable for perimeter detection systems
No sensors should be mounted on the outside fence
125
Exterior, perimeter intrusion sensors
Physical & environmental conditions affecting perimeter detection system
**Topography** (gullies, slopes, water, etc)
**Vegetation** (motion from wind, sources of concealment/cover)
**Wildlife** (large animal interference with sensors, small animal burrowing & chewing
**Background noise** (wind, traffic, EMI, seismic activity)
**Climate & weather**
**Soil & pavement** (soil conductivity, seismic conductivity)
126
Exterior, perimeter intrusion sensors
Barriers designed to delay intrusion should be placed **along the inner fenceline of a dual-fence line clear zone, to prevent tampering with the barriers without first traversing the detection zone**
127
Exterior, perimeter intrusion sensors
**A clear zone "compromise" width between 10 & 15 yds.** facilities reduction of nuisance alarms (wide) & high resolution for alarm assessment by cameras (narrow)
128
Interior intrusion sensors
Interior application sensors are divided into 3 categories
Boundary - penetration
Interior - motion
Proximity - sensors
129
Interior intrusion sensors
Two important physical conditions that affect sensor performance
**Building or room construction**
**Equipment & objects that occupy the space**
130
Interior intrusion sensors
Electromechanical Sensors
- Passive, visible, line/point sensors
- Magnetic reed switches (doors, windows, etc..)
- Balanced magnetic switches (BMSs) or bias magnets higher sensitivity than reed switches, less susceptible to spoofing
- Hall effect switch detects field of magnet-no moving parts - measures charge separation & polarity - most advanced switch
- Continuity/break wire - wires embedded or attached to surface, activated by cutting (security screens) low NAR (may use optic fibers instead)
131
Interior intrusion sensors
Vibration Sensors
- Passive visible or covert
- Jiggle switches
- Inertial switches: a metal ball mounted on metal contacts - detects vibration frequencies between 2-5 KHz
- Piezoelectric sensors: sensing element that flexes at frequencies between 5-50 KHz
- Fiber-optic cables detect micro-bending caused by vibration
132
Glass-break Sensors
- Glass-mounted, passive (vibration activated); detect \> = 20 KHz vibrations
- Glass-mounted, active; generate vibrations received by another device elsewhere on the glass (lower NAR)
- Ceiling-mounted, passive; listen for the frequency of breaking glass; volumetric by design; not vibration activated
133
Interior Motion Sensors
- Monostatic microwave (common)
- Passive infrared (PIR) (Common)
- Dual Technology
- Video motion detection (VMD)
134
Interior intrusion sensors
Passive Infrared (PIR)
- Passive to human heat approximately equal to heat from the 50-watt incandescent light bulb
- Responds to infrared energy in the walkthrough band between 8 & 14mm
- Minimum Resolvable Temperature: Difference in heat between target & background (can be as low as 1-degree Celsius)
135
Interior intrusion sensors
Microwave
- Active, visible, volumetric
- 10 GHz frequency range: senses doppler shift of the returned frequency
- Best positioned to sense aggressors moving towards or away from a sensor; slow-moving targets may spoof microwave sensors
- Microwave horn, printed circuit planar, or phased array antenna
- Various detection patterns available; concave portion of detection zone is vulnerable
136
Microwave
- Penetrates most glass & normal wall materials (not metal)
- Immune to high air turbulence & temperature /changes; susceptible to "pattern drift"
- Often used in automatic door openers; multiple microwave sensors in the same area must be on different frequencies
- Ionized gas in fluorescent lighting can reflect microwaves & cause nuisance alarms
137
Proximity Sensors
- Pressure Mats
- Capacitance Sensors
138
Pressure Mats
- Largely obsolete - replaced by motion detectors
- Detected weight 5-20 lbs per sq. ft
- Still used in security portals (man traps) to prevent tailgating - based on valid user's weight in database
139
Capacitance Sensors
- Large, electrical condenser that radiates energy
- Detects changes in capacitive coupling between antenna & the ground
- Target touches protected object & absorbs some of the radiated energy generating on alarm
