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Published bySamson Gilbert Modified over 9 years ago
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Automatic Person Location Technologies and Solutions for Public Safety Users Roger Dowling Deputy Managing Director – Sepura Limited Board Member – TETRA MoU Association
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Agenda 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
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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 Blue Light Forces now mandating APLS
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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
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Solution Influencing Factors Price Accuracy verses coverage – Requirements differ for non emergency situations Varying locations - in city, in building Ergonomics Power consumption Timing of solution to reach the market Standard solution or proprietary ? Can the solution be supported by TETRA ? – Network support and bandwidth requirements
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Command & Control Requirements Effective management Requirements differ from AVLS User needs to feel unthreatened by APLS Updated positioning details fixed to various duties Linking of various systems/databases to provide officer with advance warning of possible dangers
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Resource management - AVLS
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Resource management - APLS
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Resource management –filtering applied
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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
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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) – low cost, 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
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Network Based Solutions LMU Radio tower C&C Server GIS or Mapping Application GIS or Mapping Application TETRA Gateway LMU Network Based Solutions Current Accuracy = 200m - 2km Future Accuracy =100m - 500m
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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 Note, all the above have a location accuracy of <10 metres for 95% of cases in open space
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GPS based solutions Dispatch workstations Radio tower PBX Workstation Mapping Application TETRA Network Workstation Mapping Server Base station TETRA gateway C&C firewall C & C LAN SDS C & C Servers
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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
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GPS - High accuracy
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Data over network - Size of problem! Typically, position report messages could carry some or all of the following: – Date, Time, Latitude, Longitude, Altitude, Speed, Heading, Fix type, Confidence Level, Status, Fix Reason, Terminal ID, User Defined Field. Amount of message traffic generated by APLS systems is much larger than for AVLS – Usage could increase 10 or 100 fold ! – Requires sophisticated filtering at command &control
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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! – In busy periods, with many location reports being sent, this could cause the network to be overloaded 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!
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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 DofD GPS system.
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Clear Sky Under Foliage Wooden Building Urban Canyon Single Storey Brick Building Multi Storey Concrete building Underground? 2002 2003 2004 2005 2006 2007 2008 2010………………………….. 2015 2020 2030 High sensitivity GPS L1, L2 + L5 Frequency (+ Galileo?) Galileo Future GPS ? Other Sensors – e.g. Gyroscope, Accelerometers “GPS” Performance - Trend High Quality Receiver High Quality Hand Held Receiver
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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 Make GPS mandatory in your handset today
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User Trials – GPS comparison Product A Product B 4 times improvement in accuracy & availability User Trial Essential!
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Summary Many different location technologies available Technology for both location based and TETRA is rapidly changing High sensitive GPS receivers currently provides the best fit for public safety requirements. Sepura has an ongoing programme to identify solutions and bring these quickly to market
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MANY THANKS Any Questions ?
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What is GPS
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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.
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GPS How Does It Work ? By working out the distances from each satellite the GPS receiver can calculate its position on the intersection of the spheres. As can be seen in this diagram only one of the possible positions can be correct. The second implausible position is discarded. Three satellites provides the GPS receiver with a two dimensional navigational fix. Four satellites provides the GPS receiver with a three dimensional fix
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