Transcript Document

Automatic Person Location
Technologies
and
Solutions for Public Safety Users
Peter Hudson
Sepura
28.10.2005
Introduction
Market requirements for APLS for Public Safety users
The command and control requirements of an APLS solution
Review of location technologies
TETRA services used for location solutions
Future of APLS enabled products for public safety users
Market Requirement Drivers – APLS
FCC E911 Mandate in the US
 Call centres
 Terminal or network implemented solutions
50 - 100 metre accuracy for at least 67% of cases
150 - 300 metre accuracy for at least 95% of cases
EU E112 Mandate in Europe
 Still not implemented !
 No defined accuracy specified !
Both systems proposing using either TDOA or GPS location techniques
Many emergency services now mandating APLS
Location Technology - Public Safety
Know where someone is: save LIFE.
Better allocation of resources, prompt reaction to an Emergency: save TIME.
Better Control of the fleet: save MONEY
Improve job satisfaction: save CHURN
Solution Influencing Factors
Price
Accuracy verses coverage
Ergonomics
Power consumption
Timing of solution to reach the market
Standard solution or proprietary ?
Can the solution be supported by TETRA ?
Command & Control Requirements
Effective management
Requirements differ from AVLS
User needs to feel unthreatened by APLS
Updated positioning details fixed to various duties or skills
Linking of various systems/databases to provide officer with advance
warning of possible dangers
Resource management - AVLS
Resource management - APLS
Resource management
Importance of knowing location
High
Accuracy
Low
Accuracy
 HELP!....
Which street are you in?

Location Solutions & Performance
Low accuracy, low cost solutions
 Time difference of arrival
 Enhanced observed time difference
Medium accuracy, medium cost solutions
 Standard GPS
 Assisted GPS
 Low signal strength GPS
High accuracy, high cost solutions
 Differential GPS
 Combinations of Solutions
Low accuracy, low cost (terminal) solutions
Time Difference Of Arrival (TDOA)
 very costly to implement in the network
 accuracy of location is +/- 500 metres
Enhanced Observed Time Difference (EOTD)
 no base station support now claimed
 accuracy of location is 200m - 2km
Both technologies
 have good indoor/urban canyon penetration, but with very poor accuracy a general show stopping issue for network based solutions where location
accuracy could be critical
 are bandwidth hungry therefore not suitable for TETRA
Network Based Solutions
LMU
Radio tower
LMU
Radio tower
TETRA
Gateway
C&C
Server
GIS or
Mapping
Application
GIS or
Mapping
Application
Network Based Solutions
Current Accuracy = 200m - 2km
Future Accuracy =100m - 500m
LMU
Radio tower
LMU
Medium accuracy, medium cost solutions
Standard GPS
 time to first acquisition (fix) is typically 3 mins
 >30 metres accuracy, no indoors or urban canyon coverage
Assisted GPS
 time to first acquisition is typically 30 secs
 >30 metres accuracy
Low Signal Strength GPS (high sensitivity)
 time to first acquisition is typically 45 secs
 <30 metres accuracy
 indoors/urban canyons
All the above have a location accuracy of <10 metres for 95% of cases in open space
GPS How Does It Work ?
To enable a location measurement to be made, the GPS receiver needs
to know were the satellites are
It receives two kinds of data from the satellites;
 Almanac data
 Ephemeris data
Once the receiver has obtained this information it needs to synchronise
time before an accurate location measurement can be made.
By knowing time taken to receive signal from each satellite, the receiver
can determine exactly how far away it is.
GPS based solutions
Mapping
Server
C&C
Firewall
Mapping
Application
C & C LAN
TETRA
gateway
TETRA
Network
Dispatch
workstations
SDS
Radio tower
C & C Servers
Base station
High accuracy, high cost solutions
Differential GPS
 open space accuracy <10 metres off
 expensive to implement with land based differential base stations required and regular network
broadcasts
 Network bandwidth hungry
Solution Combinations (GPS+Beacons+Odometer)
 accuracy anywhere between 0 - 10 metres
 very expensive beacon network required to support this
GPS - High accuracy
TETRA
Network
Radio tower
Radio tower
GIS or
Mapping
Application
TETRA
Gateway
GIS or
Mapping
Application
GPS
Server
C&C
GPS Station
Radio tower
SDS
Radio tower
Beacon
Receiver
GPS
Odometer
Data over network - Size of problem!
Typically, position report messages could carry some or
all of the following:
Date
Heading
Time
Fix type
Latitude
Confidence Level
Longitude
Status
Altitude
Speed
Fix Reason
Terminal ID
Amount of message traffic generated by APLS systems is
much larger than for AVLS
TETRA services for APLS
TETRA services allow use of SDS messaging for transmission of GPS data:-
EN 300 392-2: TETRA (Voice plus Data (V+D), part 2: Air Interface, v2.3.2
 SDS4 and SDS-TL delivers variable length messages to 2047 bits(255 bytes)
 GPS location data is provided in the NMEA formats, GLL, GSA, GGA etc.
 Typical GLL mesage could contain as much as 48 bytes of data!
Location Information Protocol –TS 100 392-18-1 v1.1.1 Jan 2005
 Specifies the effective use of network by using compact message formats
 Typical message (compared to GLL) is 11 bytes long!
Future of APLS & TETRA Terminals
Technology Influenced Solutions
Continuing integration of IC’s and components enables space saving in
handsets and is an opportunity to integrate location devices like GPS.
The European Galileo system should be operational by 2008 and this is
supposed to perform better than the existing US DoD GPS system.
“GPS” Performance - Trend
Galileo
Clear Sky
L1, L2 + L5
Frequency
(+ Galileo?)
High Quality
Receiver
Under Foliage
Future
GPS ?
High Quality
Hand Held
Receiver
Wooden
Building
Urban Canyon
High sensitivity GPS
Single Storey
Brick Building
Multi Storey
Concrete building
Other Sensors – e.g. Gyroscope, Accelerometers
Underground?
2002
2003 2004 2005 2006 2007 2008
2010………………………….. 2015 2020 2030
Benefits of GPS in Public Safety
Enhances user safety
Lone worker + Emergency Button + GPS
Accurate Location
Improves resource usage
Improves response times
Selection of most appropriate resource
Reduce wasted resource
Improves reporting accuracy
Knowing precisely where an incident took place
Improves user job satisfaction
User feels safer and more confident