Communication Dispatch Centers

Copyright Protected 2005: Hi Tech Criminal Justice, Raymond E. Foster
Police TechnologyPolice Technology
Chapter SevenChapter Seven
CommunicationsCommunications
Dispatch CentersDispatch Centers

Copyright Protected 2005: Hi Tech Criminal Justice, Raymo
Learning ObjectivesLearning Objectives
 How hardwired and wirelessHow hardwired and wireless universaluniversal
emergency numberemergency number calls reach acalls reach a publicpublic
safety answering pointsafety answering point..
 What kinds of information areWhat kinds of information are
automatically included in a 9-1-1 callautomatically included in a 9-1-1 call
 Basic functions ofBasic functions of computer aidedcomputer aided
dispatchdispatch systemssystems
 Basic functions of anBasic functions of an intelligent transportintelligent transport
systemsystem

IntroductionIntroduction
The dispatch center’sThe dispatch center’s
primary purpose:primary purpose:
 Manage calls for serviceManage calls for service
from the publicfrom the public
 Provide communicationProvide communication
and information supportand information support
to field police officersto field police officers
 Some center’s are theSome center’s are the
first point of collection offirst point of collection of
police statisticspolice statistics
Photograph provided by Gary Allen, Dispatch Monthly Magazine

Public Safety Answering PointPublic Safety Answering Point
The first task of the dispatch center is to be theThe first task of the dispatch center is to be the
public safety answering point (PSAP)public safety answering point (PSAP)
Today, 9-1-1 calls go
to the PSAP

Universal Emergency NumberUniversal Emergency Number
Before 9-1-1, peopleBefore 9-1-1, people
could:could:
 dial the operator ordial the operator or
 dial the police (fire,dial the police (fire,
ambulance) directlyambulance) directly
The telephone operator was theThe telephone operator was the
de facto public safetyde facto public safety
answering point.answering point.

 When 9-1-1 service began, you wereWhen 9-1-1 service began, you were
connected with your PSAP, but onlyconnected with your PSAP, but only
your telephone number was availableyour telephone number was available
to the PSAP. No address, name, etc.to the PSAP. No address, name, etc.

 Your telephone sends out anYour telephone sends out an automaticautomatic
identification number (AIN)identification number (AIN) signal (thesignal (the
telephone number and a digit representing thetelephone number and a digit representing the
area code).area code).
Think about your own
caller ID system. The
number you see on the
display is the AIN signal,
IF you pick up, you hear
the voice signal!

 When a 9-1-1 call is made, the voiceWhen a 9-1-1 call is made, the voice
signal and the AIN pass through thesignal and the AIN pass through the
local exchange carrier switch and arelocal exchange carrier switch and are
routed through the 911 tandem.routed through the 911 tandem.
 The tandem reads the AIN and forwardsThe tandem reads the AIN and forwards
the call to the appropriate PSAP.the call to the appropriate PSAP.

 Enhanced 9-1-1Enhanced 9-1-1 automatically queries aautomatically queries a
telephone company database thattelephone company database that
converts AIN information into the physicalconverts AIN information into the physical
location of the telephone.location of the telephone.
 The information on the location is theThe information on the location is the
automatic location information (ALI)automatic location information (ALI)

Your telephone number
and location are
automatically displayed
to the PSAP operator
Screen capture provided by Crimestar, Inc
Telephone Number
Location

What about cellular 9-1-1 calls?What about cellular 9-1-1 calls?
 ANI information is obtained in a similarANI information is obtained in a similar
manner….manner….
But, cellular telephone do not have a fixedBut, cellular telephone do not have a fixed
location…….in the past, cellular telephoneslocation…….in the past, cellular telephones
determined the default PSAP by transferringdetermined the default PSAP by transferring
your call to a regional agency, like the stateyour call to a regional agency, like the state
police.police.

Angle on Arrival (AOA).Angle on Arrival (AOA).
A cellular telephoneA cellular telephone
location can belocation can be
determined using Timedetermined using Time
Distance on Arrival andDistance on Arrival and
Angle on ArrivalAngle on Arrival

The signal from at leastThe signal from at least
two cell sites is used totwo cell sites is used to
calculate the position ofcalculate the position of
the vehiclethe vehicle

Based on the positionBased on the position
asas
calculated, the cellularcalculated, the cellular
system routes the callsystem routes the call
to the appropriateto the appropriate
PSAP,PSAP,

Computer-Aided DispatchComputer-Aided Dispatch
 CAD describesCAD describes
software applicationssoftware applications
and hardware thatand hardware that
assist in theassist in the
management ofmanagement of
dispatching calls fordispatching calls for
service.service.
 It is a managementIt is a management
tool that automatestool that automates
the many functions ofthe many functions of
a dispatch center.a dispatch center.
Photograph provided by Randall Larson, Editor, 9-1-1 Magazine

 Also provides access to other databasesAlso provides access to other databases
and acts as interface software in the two-and acts as interface software in the two-
way voice communications betweenway voice communications between
dispatch and the field units.dispatch and the field units.

 CAD systems areCAD systems are
used by manyused by many
companies thatcompanies that
dispatch vehicles –dispatch vehicles –
delivery, taxis, buses,delivery, taxis, buses,
etc.etc.

The most important part of CAD isThe most important part of CAD is
thethe
software and various othersoftware and various other
systemssystems
with which CAD can interface.with which CAD can interface.
 The workstation is connectedThe workstation is connected
to the commercial telephoneto the commercial telephone
networknetwork
 It captures information aboutIt captures information about
9-1-1 calls and field-generated9-1-1 calls and field-generated
incidents – constructs a hugeincidents – constructs a huge
relational databaserelational database

On the strategic side, a fully integratedOn the strategic side, a fully integrated
CAD system can be sued toCAD system can be sued to
 Assess deployment needsAssess deployment needs
 Provide information on problemProvide information on problem
locationslocations
 Provide the initial incident numberProvide the initial incident number
that will be sued to reference allthat will be sued to reference all
subsequent evidence, reports, andsubsequent evidence, reports, and
police activitiespolice activities

Some PSAPsSome PSAPs
 Handle emergency calls for police, fire,Handle emergency calls for police, fire,
and emergency medical servicesand emergency medical services
 Handle the police, but transfer fire/medicalHandle the police, but transfer fire/medical
callscalls
 Have dispatchers handling business callsHave dispatchers handling business calls
throughout the police stationthroughout the police station

Obtain Info
Location?
Offense?
Weapons?
Descriptions
?
Caller Info?
Update Info
Keep Caller on Line
CALL
RECEIVED
Emergency
?
Yes
?
E 9-1-1 provides
ANI and converts
the info into the
call for service.
Verify ANI info

Obtain Info
Location?
Offense?
Weapons?
Descriptions
?
Caller Info?
Update Info
Keep Caller on Line
CALL
RECEIVED
Emergency
?
Yes
?
No? Transfer?
Provide info Yes
?
No?
Information?
Yes
?
No?
Cold Crime?
No?
Other Action

Obtain Info
Location?
Offense?
Weapons?
Descriptions
?
Caller Info?
Update Info
Keep Caller on Line
CALL
RECEIVED
Emergency
?
Yes
?
No? Transfer?
Provide info Yes
?
No?
Information?
Yes
?
No?
Cold Crime?
No?
Other Action
Yes
?
Obtain Info
Offense?
Location?
When?
Caller Info? Contact at?

Nonemergency Points of ContactNonemergency Points of Contact
 3-1-1: Non-emergency3-1-1: Non-emergency
telephone calls (sometelephone calls (some
jurisdictions)jurisdictions)
 4-1-1: Directory information4-1-1: Directory information
 6-1-1: Telephone repair6-1-1: Telephone repair

Intelligent Transportation SystemsIntelligent Transportation Systems
ITS allows dispatcher accessITS allows dispatcher access
to real-timeto real-time
Traffic information from:Traffic information from:
 Closed-circuit televisionClosed-circuit television
(CCTV)(CCTV) camerascameras
 Sensors under the street.Sensors under the street.

Intelligent Transportation SystemsIntelligent Transportation Systems
 Can give emergencyCan give emergency
respondersresponders
information on:information on:
 Nature of emergencyNature of emergency
 Best Route to locationBest Route to location

Copyright Protected 2005: Hi Tech Criminal Justice, Raymond E. Foster
Police TechnologyPolice Technology
Go to theGo to the Student ResourcesStudent Resources page atpage at
www.hitechcj.comwww.hitechcj.com

Communication Dispatch Centers

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