1. The University of Adelaide, School of Computer Science
Effective Physical Security
Fourth Edition
The University of Adelaide, School of Computer Science
12 June 2018
Chapter 10
Alarms: Intrusion Detection Systems
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Chapter 2 — Instructions: Language of the Computer

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Alarms
Factors in selecting proper alarm system:
Threat or risk
Type of sensors needed
Methods available to provide level of protection needed
Method of alarm signal transmission
#10 Alarms: Intrusion Detection Systems
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Alarms
Variety of methods to provide protection.
Combination in thousands
Intruder detection system may deter intruder
Primary function of alarm system—signal presence of intruder
May be supplemented with security personnel and other security mechanisms
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4. Alarm System Components
Perimeter Protection:
First line of defense in detecting intruders
Sensing devices on:
Doors
Windows
Vents
Skylights
Any other openings
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5. Alarm System Components
More than 80% of all break-in occur in those entrances.
Major advantage—simple design
Major disadvantage—protects only openings
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6. Alarm System Components
Other components:
Door switches
Glass break detectors
Wooden screens
Window screens
Lace and panels
Interior sensors
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7. Area/Space Protection
Devices to protect interior spaces
Protect against intrusion whether or not perimeter protection was violated
Effective against:
A stay-behind intruder
Intruder who cuts through roofs or breaks through a block wall
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8. Area/Space Protection
Only a part of complete alarm system
Should be supplemented by perimeter protection
Advantage—highly sensitive, invisible means of detection
Disadvantage—improper application or installation can cause frequent false alarms
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9. Area/Space Protection—Types
Photoelectric eyes (beams)
Transmit beam across protected area
When interrupted, alarm is activated
Invisible to naked eye
Can be used outdoors
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10. Area/Space Protection—Types
Ultrasonics (rarely used today)
Work on low-frequency sound wave
Coverage area from 5 to 20 feet
Pattern volumetric and cannot be aimed
Pattern can be directed by deflectors
Work on change in frequency, Doppler effect
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11. Area/Space Protection—Types
Ultrasonics (con’t)
Motion detector has two transducers
If intrude moves toward or away from unit, change in reflected frequency signals alarms
Stand-alone unit—compares reflected signal
Master system—sends signal back to main processing unit
False alarms from:
Motion
Noise
Radio or electrical interference
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12. Area/Space Protection—Types
Ultrasonics (con’t)
Grounding and shielding important in a master system
Ground wire length be short as possible
Potential problems:
Turbulence and draft, hanging displays
Noise from air hissing, bells, and telephones
Temperature/humidity affects range of unit
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13. Area/Space Protection—Types
Microwave—volumetric type of space protection, based on Doppler shift
Use radiated RF electromagnetic field
Frequency range between 0.2 and 300 GHz
Motion creates change in frequency, triggering alarm
Penetrates most objects and reflects off metal.
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14. Area/Space Protection—Types
Microwave (con’t)
Vibration an important consideration
Must be mounted on firm surface
Do not mount two microwave units with identical frequencies in same room or area
Cause false alarms
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15. Area/Space Protection—Types
Microwave (con’t)
Draw excessive current
Take into account proper guage of wire and length of wire
Take current readings at end of installation or while troubleshooting
Fluorescent lights may be problematic.
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16. Area/Space Protection—Types
Microwaves (con’t)
Potential problems
Vibration/movement of mounting surfaces
Reflection/pattern of movement of metal objects
Penetration of thin walls or glass
RFI, radar, AC line transients problematic
Water movement in plastic/PVC storm drains may interfere
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17. Area/Space Protection—Types
Passive infrared motion detectors
Passive sensors—do not transmit signal for intruder to disturb
PIRs detect change in thermal energy pattern
Field of view must end on an object rather than mid-air
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18. Area/Space Protection—Types
Passive infrared motion detectors (con’t)
Potential problems:
Turbulence causing rapid temperature change
Stray motion
Changing temperatures causing false alarms
Lightning/bright lights
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19. Area/Space Protection—Types
Pressure mats
Mechanical switches
Backup system to perimeter protection
Hidden under carpet in front of target or in hallways
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20. Area/Space Protection—Types
Sound sensors
Pick up noise created during break-in
Consist of microphone and electronic amplifier/processor
Sound level increasing beyond normal limit signals an alarm
May have pulse-counting and time-interval features
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21. Area/Space Protection—Types
Dual-technology sensors
Combination of two types of space-protection devices
Both must be tripped at same time to set off alarm
Combination of:
Passive/microwave
Passive ultrasonic
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22. Area/Space Protection—Types
Used in areas that may have potential false alarm problems with single-tech units
More to consider with two techs
Draw more current
If one section of unit stopped working, unit was inoperable (more a problem in the past)
If one unit section continuously in an alarm condition, dual-tech is worthless.
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23. Area/Space Protection—Types
Interior sensors
Active or passive
Covert or visible
Volumetric or line applications
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False Alarms
Reasons for false alarms:
Lack of education on how to enter and exit the complex
Weather
Equipment failure
Installation problems
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25. Area/Space Protection—Application
Not necessary to cover every inch
Best placement—a trap in high-traffic afrea or protection for high-value area
Do not overextend protected area
Ensure adequate power
Adjust for pets and brief customers
Walk-test all units and mask out areas
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26. Area/Space Protection—Application
Zoning an important consideration:
Do not place two interior devices in one zone
Causes false alarms
Breaking up interior protective circuits as much as possible—better chance of solving false alarms
Helps with troubleshooting
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27. Object/Spot Detection
Detects activity/presence of intruder in a single location
Direct security for objects
Final stage of in-depth protection system
Most frequently protected items:
Safes and filing cabinets
Art objects and statues
Expensive equpment
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28. Types of Object/Spot Protection
Capacitance/proximity detectors
Object electronically linked to alarm control
When approached or touched, the electrostatic field is unbalanced
Alarm is initiated.
Only works with metal objects
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29. Types of Object/Spot Protection
Vibration detectors
Use specialized microphone, electronic vibration detector (EVD)
Attached directly to object being protected
Sends alarm only when object is moved
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Alarm Control
Sensing devices wired into alarm control panel
Type of control panel depends on overall system
Some provide zoning capabilities for separate annunciation.
Others provide low-voltage electrical power for sensing devices.
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Alarm Control
Backup or standby power for control panel
Batteries—often rechargeable to maintain full power
Modern control panels—one or more microprocessors
Allows panel to send and receive digital information
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Alarm Control
Alphanumeric pad to display zone info
Each user can have unique code
Restriction during specified times or access to certain areas
Track activity
Transmit information off-site
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Alarm Control
If control panel is connected to a central monitoring station:
Turning system on and off is recorded and logged.
If during prearranged time—normal opening
Other times– police dispatched
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Alarm Control
Tamper protection
Generates alarm signal when system is compromised
Can be designed in any part of alarm system
Control panel
Sensing devices
Loop wiring
Alarm transmission facilities
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35. Alarm Transmission/Signaling
Type used depends on:
Location of business or residence
Frequency of police patrols
Affordability
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36. Alarm Transmission/Signaling
Types of alarm signaling systems in use:
Local alarm
Bell or light indicates intrusion
Success relies on hearing or seeing alarm and calling authorities
Notifies burglars they have been spotted
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37. Alarm Transmission/Signaling
Central station system
Alarm signal transmitted to a central station
Trained operators on duty 24 hours a day
Police dispatched and alarm company guard (if available)
Thorough documentation
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38. Alarm Transmission Types to Central Station
Direct wire systems
Generally for high-risk locations
Dedicated phone line from protected premises to central station or police station
Fixed DC current from central station to premises, read on meter at the station
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39. Alarm Transmission Types to Central Station
Direct wire system (con’t)
Advantage—problem can be traced quickly to specific alarm system
Makes compromise by burglar more difficult
Disadvantages—higher cost of leased telephone lines
More distance, more cost
Problems in transmission
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40. Alarm Transmission Types to Central Station
Circuit (party line) systems
Several customers share transmission system
Defrays cost
May be as many as 15 to a single receiving panel
Each alarm has distinctive code
Advantage
Lower costs
Disadvantage
More difficult to locate problems on the line; taking longer to fix the problem
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41. Alarm Transmission Types to Central Station
Multiplex system
Designed to reduce leased telephone line charges
Provides higher degree of line security than circuit-loop alarms
Introduce data processing to system
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42. Alarm Transmission Types to Central Station
Digital communicators
Computer-based alarm transmission equipment
Sends signal through regular switch line phone network
Signal a series of coded electronic pulses that is received only on a computer terminal
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43. Alarm Transmission Types to Central Station
Telephone dialer
Dialer delivers a prerecorded verbal message when an alarm is activated.
Modern versions solved problems of:
Most of message played before police answered phone
Knew a signal was sent, but not from where.
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44. Alarm Transmission Types to Central Station
Radio signal transmission
Sends alarm signal from protected premises via radio or cell phone to central station/police dispatch center
Can be received in police patrol car
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45. Alarm Transmission Types to Central Station
Video verification
Video images sent to central station along with alarm transmissions
Higher level of protection
Eliminates false alarms
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Alarms Deter Crime
National Crime Prevention Institute—alarm systems as best available crime deterrent
Crisis prevention duties of alarm firms
Monitoring sprinkler systems and fire sensors
Monitoring temperature levels
Supervising industrial processes
Deterrence a specialized art
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False Alarms
Alarm systems prevent crime
Most effective and economical crime prevention tool available
False alarms erode effectiveness of alarm systems
Costly to already budget-strapped alarm companies and police
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False Alarms
NBFAA survey listed as a major need:
Comprehensive program to reduce false alarms
Many members already researching problem
Police responses:
Written letters
Follow-up visits
Some assessing false alarm fines after other steps have failed
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49. Alarm Equipment Overhaul
Alarm station did a major overhaul
Begins with false alarm inventory
Subscribers with four or more false alarms weeded out
Alarm systems replaced for those subscribers
New sensors, batteries, wiring, soldering
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50. Alarm Equipment Overhaul
NBFAA member companies
Training programs for personnel
Subscribers education on systems operation three times:
Salespeople
Installers
Supervisors
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Additional Resources
NBFAA quality control manual:
False Alarm Handbook
Determine false alarm rates and causes
Evaluation committee
Equipment testing procedures
Equipment training facilities
How to plan and install alarms
Sensor zoning procedures
Inspect installations
Educate subscriber
Cooperate with local law enforcement
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