1AUTOMATIC VEHICLE LOCATOR BASED ON SATELLITE COMMUNICATIONPresented by K.PAVANKUMARDepartment of ECE,3 YearSRIKALAHASTEESWARA INSTITUTE OF TECHNOLOGYE-mail: chekdepa1@gmail.com ph no:9966609036FORSIDDHARTHA INSTITUTE OF TECHNOLOGYPUTTURABSTRACT Is your car or a vehicle stolen or is it not visible in the thickest snow or is one among the several cars present? Do you wa nt toknow the arrival of the bus for which you are waiting? Are your children going alone in a vehicle and you want to track theirmoments? Does your cargo consists of costly load and want to protect them? Do you want to keep track of your little playingkids about where they are?ANS: Automatic Vehicle Locator.This Paper gives us a novel approach of using certain GPS technology in tracking not only vehicles, but even children andto protect precious goods. So this technology has gained a lot of importance in the recent years. This paper tells us how thistechnology works, its applications. It is still under research and development stage.1. AUTOMATIC VEHICLE LOCATORAutomatic vehicle location (AVL) is a computer -basedvehicle tracking system. For transit, the actual real -timeposition of each vehicle is determined and relayed to acontrol center. Actual position determination and relaytechniques vary, depending on the needs of the transitsystem and the technologies employed. Transit agenciesoften incorporate other advanced system features inconjunction with AVL system implementation. SimpleAVL systems include: computer -aided dispatch software,mobile data terminals, emergency alarms, and digitalcommunications. More sophist icated AVL Systems mayintegrate:real-time passenger information, automaticpassenger counters, and automated fare payment systems.Other components that may be integrated with AVLsystems include automatic stop annunciation, automateddestination signs, Vehicle component monitoring, andTraffic signal priority.AVL technology allows improved schedule adherenceand timed transfers, more accessible passengerinformation, increased availability of data for transitmanagementand planning,efficiency/productivityimprovements in transit services.2. What is AVL technology? Automated Vehicle Locator (AVL) systems use satelliteand land communications to display each vehicle'slocation, status, heading, and speed on the computer'sscreen. AVL systems use one of four types of navigationtechnology, or may combine two of these technologies tocompensate for inevitable shortcomings of any onetechnology.The four principal technologies employed for AVLsystems are:1. Global Positioning System2. Dead-Reckoning System3. Signpost/Odometer Systems4. Radio Navigation/Location3. TRACKING SYSTEMSThere are two types of tracking systems.3.1. PASSIVE TRACKING: The Passive Tracking Systemmodality refers to stand-alone GPS Receivers, which storedata for further process. Passive systems are typicallylimited to vehicle tracking only. When a Passive TrackingDevice is installed in a vehicle, the location, time, velocityand heading data is usually stored in the unit or transferredto a handheld device and downloaded from the vehiclewhen the vehicle returns to their base station.3.2. REAL TIME TRACKINGReal Time Tracking Systems are based on mobilestand-alone terminals which combine GPS and GSMtechnology to determinate and transmit their position. Atwo-way wireless communication link connects the unitwith the control center at all times. A portable GPStracking device can be used as an emergency cellularphone with speed dialing for two -way voicecommunication. It can silently call any emergency numberin the world for immediate assistance. The emergencysilent call feature also provides a digitized voice messagewhich can report the time, date, speed, heading, andlocation of a person in distress.Figure1. GPS ReceiverThe AVL tracking system consists of a GPS receiver insidethe vehicle and a communications link betwee n the vehicleand the control Center as well as pc -based trackingsoftware for dispatch. The communication system isusually a cellular network similar to the one used bycellular phone. Currently all kind of communicationsnetworks permit Real-Time Tracking for mobile assets.4. WORKING OF A GPS BASEDAUTOMATIC VEHICLE LOCATOR 4.1. GPS SATELLITESThe GPS satellites locate the transit vehicles bysending out GPS signals to be picked up by vehicles GPSUNITS. The GPS unit in the vehicle absorbs the signalsand gives radio signals to the RADIO system.Figure2. A GPS Based AVLSystem4.2. RADIO SYSTEMThe RADIO systems receive the vehicle GEO -LOCATION coordinates and transmits th is radio signals tocommunication center.4.3. COMMUNICATION CENTERThe communication center receives this information anduses it to determine the location of transit vehicle andsends this to dispatch stations and other stations for furtheranalysis of the information either through wire line orwireless networks.4.4. DISPATCH SECTIONThe dispatch section uses the vehicle information to helpmaintain transit schedules and provide operational supportto the drivers.4.5. CUSTOMER ASSISTANCE UNITThe customer assistance planning/scheduling operationsanalysis unit also receives the vehicle location informationthrough wire line or wireless network. This section usevehicle location map to help maintain transit schedules toanalyze and provide traffic information for other road waydriver.Figure3. Working of a GPS based AVL5. INTEGRATING AVL WITH OTHERSYSTEMSBuses equipped with AVL offer many possibilities fortransit interface with highway and traffic organizations ortransportation management centers. Opportunities include:providing transit buses with traffic signal priority;obtaining traffic congestion data at the dispatch center toallow rerouting of buses or informing customers of delay;incorporating transit information in traveler informationsystems; developing multi -application electronic paymentsystems; using buses to automatically communicat e trafficspeed; and reporting of roadway incidents by transitvehicle operators. 6. MORE ABOUT GPS6.1. Use of Differential GPSFor AVL systems which do require more accuratepositions, differential GPS can be employed. Thesesystems normally employ the transmission of correctioninformation to the GPSreceiver;this correctioninformation has corrections for each satellite in view. Thisis done because each satellite has its own error; the error inGPS is not simply an X -Y error which will be the sa me forall receivers. The error on any two given receivers willonly be the same if those receivers are using the SAMEsatellites. This cant normally be guaranteed as satellitesmay be obscured at one location, making the error slightlydifferent for two receivers.6.2. GPS AntennasThe best position for any antenna is generally as highas possible with the best unrestricted view.6.3. GPS SatellitesThe global positioning system (GPS) was specificallyengineered so that at least four of the 24 sat ellites would bepositioned on the horizon at all times. There are sixdifferent orbiting patterns that the GPS satellites follow,making a complete trip around the earth every 12 hours.The information regarding the location of the transitvehicle is calculated by TRILATERATION method. Withthis information, the receivers can, by a process similar totriangulation, tell the user the exact location in latitude,longitude, and sometimes altitude too .Figure4. GPSSatellites6.4. MAPPINGAt any control station, data is normally required to beviewed on a map. Maps allow a tangible, understandableview of a vehicles location, and will also allow operators toapply local knowledge.7. DATA TRANSFERThe two most common methods of transmittingvehicle location data to dispatch are through polling andexception reporting via wireless communications. Manyagencies use a combination.8. BENEFITSThe most extensive and rigorous research into thebenefits of AVL has found that this technology has lead t osignificant transit firm productivity gains (whether output is measured by Passenger Miles or Vehicle RevenueMiles). Benefits have been documented to varying degreesfor all of the following categories.8.1. Operations:Increases transit rider ship. Reducedneed for additional road supervisors and manual data entry.8.2.Communications:Improved communicationsbetween supervisors, dispatchers, and operators andreduced voice radio traffic.8.3. Passenger Information:Provides capability toinform passengers of predicted bus arrival times thusenhancing the quality of transit service and allowingtravelers to make better travel decisions.8.4.SchedulingandPlannin g:Provides morecomplete and accurate data for scheduling and planning.Aids in effective bus stop placement (when combined witha G.I.S. database and automatic passenger counters).8.5. Safety and Security: Enhances the security of thedriver and traveler (particularly when coupled with silentalarm technology).9. USES1.Vehicle location display in real-time.2.Recording of arrival and departure times (proofof delivery etc).3. Monitoring of driving practices (speed). 10.3. Track Anything4.Alerts if vehicle leaves or enters a defined area .10. APPLICATIONS IN OTHER FIELDS10.1. In MilitaryIt is clear how useful this technology would be for theArmed Forces. Before small GPS receivers were available,troops in the field depended on the same technology forgenerations:the compass, sextant, maps and handcalculations. Radios and reconnaissance aircraft wer e greatleaps, but a GPS calculates position in real time, down tothree foot accuracy!10.2. Geo-CachingThis is for people who have liking towards searchinghidden things or participating in scavenger hunts. WithGPS, comes the new twist: geo -caching. Geo-catchers hidea little treasure in a box public place, for example, a shoebox with a used book inside, taped under the seat of a busstop. They then go to geo -caching websites and post simplelatitude and longitude, to as much accuracy as they like.Then other geo-catchers search for these boxes with theirGPS data. The fun is looking for a strange box in whatcould be an area with a 25 -foot radius. When thesuccessful geo-catcher finds the box, he or she keeps thelittle treasure and replaces it with another, for the nextsearcher. Parents always worry about their teenage kids, especiallyafter they start driving. Auto shops have started offeringinstallation of small, hidden GPS receivers in kids cars.Parents can then use simp le computer software and havetheir kids movements plotted on a map. Many parentsdont even tell the kids about this little extra.Figure5. Track anything10.4. In CargoSome containers of cargo are more valuable than others. Asmall GPS receiver inside the cargo can know exactlywhere it is, how far it is from the destination, and where tofind even it if it is stolen.Figure6. GPS in Cargo10.5. Child TrackingOf topical interest at this time is child tracking,giving the possibility for children to wear or carry somesort of GPS/GSM tracker. Such a device could providevaluable information if a child is abducted or lost. Signalscould be sent from the tracker every few minutes to acentral site so that a record is kept of the childs loca tion,or just sent when a panic button was pressed by the child. 12. BIBLIOGRAPHY1.www.calccit.org.itsdecision/serv_and_te ch/Automatic_vehicle_location/automatic_vehicle_location_summary.html2.http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=102387