Tracking Basics

Overview of the Vehicle Tracking System

The Vehicle Tracking System being offered by i-Diagnosis is a GPS based system that tracks the position of the vehicles in real time and also records the events for later review. The solution is capable of tracking a fleet of vehicles and keeping the administrator informed on the location of the vehicles; and alerting in case of certain events.  An overview of the working of the system is shown below:


The vehicle tracking system comprises of a Gadget installed in a vehicle. It has two antennas, one GPS antenna and another GSM / GPRS Antenna.  The Gadget gets power from the battery of the vehicle. However, it has its own back up battery also to supply power in case of power cut off from the vehicle battery. This back up battery can supply power to the VTS device for a few hours depending upon the battery installed in the unit. For GSM / GPRS communication from the device a sim card like that in a cell phone (obtained from any of the service provider) is installed in the device.

The GPS receiver in the device captures position data from the satellites, computes the position of the vehicle and sends this information in the form of GPRS data to a central base station,  This communication can also be sent in the form of SMS. Since GPRS is more efficient and cheaper it is the preferred mode. At the base station location information is plotted using GIS maps and this information is made available to the users through web server. The user can open the browser on any PC / laptop or palm top and can see the vehicle position in real time. User can change set parameters by using his / her cell phone. 

VTS Device

A normal VTS Device or Automatic Vehicle Locator (AVL) system basically receive GPS satellite signals, Calculates the vehicle position, speed, heading and altitude, Communicate with the base station using different GPRS or GSM cellular technologies. It Uses an intelligent engine to decide when to report data and how to receive the precise time and date and Log data track geographic location. This device is supplied with GPS and GSM / GPRS Antennas, power cable and battery. A SIM with GPRS capability is obtained from a service provider and inserted in the device in the same manner as in a cell phone.




What is GPS

The Global Positioning System (GPS) is a worldwide, satellite-based, radio navigation system which gives the exact position of vehicles (in which the GPS device is installed), no matter where they are, what time it is, or what the weather is like. There are a total of 24 satellites orbiting the Earth. Each satellite transmits a unique code, its exact location and a very precise time code. On earth, the GPS receivers take this satellite data from multiple satellites and - using an algorithm & the time stamps - calculate the individual distances of each satellite from the GPS receiver. With some clever calculations, these can then point the precise location on Earth where the signal is received. The precise location is then transmitted by any of the available methods such as mobile phones (GSM/GPRS, WCDMA), Wireless (RF, WiFi, WiMax) and even a Satellite uplink for remote locations.

Global Positioning System satellites transmit signals to equipment on the ground. GPS receivers passively receive satellite signals; they do not transmit. GPS receivers require an unobstructed view of the sky, so they are used only outdoors.  GPS operations depend on a very accurate time reference, which is provided by atomic clocks at the U.S. Naval Observatory. Each GPS satellite has atomic clocks on board.

Each GPS satellite transmits data that indicates its location and the current time. All GPS satellites synchronize operations so that these repeating signals are transmitted at the same instant. The signals, moving at the speed of light, arrive at a GPS receiver at slightly different times because some satellites are farther away than others. The distance to the GPS satellites can be determined by estimating the amount of time it takes for their signals to reach the receiver. When the receiver estimates the distance to at least four GPS satellites, it can calculate its position in three dimensions.

There are at least 24 operational GPS satellites at all times. The satellites, operated by the U.S. Air Force, orbit with a period of 12 hours. Ground stations are used to precisely track each satellite's orbit.

 Determining Position - A GPS receiver "knows" the location of the satellites, because that information is included in satellite transmissions. By estimating how far away a satellite is, the receiver also "knows" it is located somewhere on the surface of an imaginary sphere centered at the satellite. It then determines the sizes of several spheres, one for each satellite. The receiver is located where these spheres intersect.

GPS Accuracy - The accuracy of a position determined with GPS depends on the type of receiver. Most hand-held GPS units have about 10-20 meter accuracy. Other types of receivers use a method called Differential GPS (DGPS) to obtain much higher accuracy. DGPS requires an additional receiver fixed at a known location nearby. Observations made by the stationary receiver are used to correct positions recorded by the roving units, producing an accuracy greater than 1 meter.

When the system was created, timing errors were inserted into GPS transmissions to limit the accuracy of non-military GPS receivers to about 100 meters. This part of GPS operations, called Selective Availability, was eliminated in May 2000.

 

What is GSM

GSM (Global System for Mobile communications is the most popular mobile communication system provided by most of the cellular service providers in most countries internationally. Its promoter, the GSM Association, estimates that 80% of the global mobile market uses the standard.GSM is used by over 3 billion people across more than 212 countries and regions. Its ubiquity makes international roaming very common between mobile phone operators, enabling subscribers to use their phones in many parts of the world. GSM differs from its predecessors in that both signaling and speech channels are digital, and thus is considered a second generation (2G) mobile phone system. This has also meant that data communication was easy to build into the system.

The ubiquity of the GSM standard has been an advantage to both consumers (who benefit from the ability to roam and switch carriers without switching phones) and also to network operators (who can choose equipment from any of the many vendors implementing GSM). GSM also pioneered a low-cost (to the network carrier) alternative to voice calls, the Short message service (SMS, also called "text messaging"), which is now supported on other mobile standards as well.

 

 


What is GPRS

GPRS (General Packet Radio Service) is a service within the GSM network, just like the two most popular services SMS und voice connections. GPRS is used for transmitting data in the GSM network in a packet-oriented way. The connection to the remote station is not reserved and left open during the entire connect time, but is occupied only at the time of actual data transmission. For using GPRS requirements are:


Advantages of using the GPRS network that several channels are occupied at the same time for data transmission whenever data needs to be transmitted. Whenever a GPRS device is not receiving or sending data the channels are available for other services and other GPRS subscribers. By way of this dynamic allotment of resources the utilization of the existing radio infrastructure is clearly optimized. In addition, the data is also compressed by means of special coding processes (CS-1...CS-4) so as to ensure a further data rate enhancement.

The dynamic allotment of resources permits a method of billing which clears the way for many potential applications in industrial data communication. The billing is not based on connect time, but rather on the data volume transmitted. This enables applications with a permanent connection, i.e. a dedicated-line operation,... "always online". Caution is demanded, however, for monthly transmission volumes beyond 50 MB. (In case of VTS device the monthly requirement is generally around 20 MB only). In such cases GPRS may very quickly lose its cost advantage. The usual transmission volume in industrial communication, however, clearly remains below this critical volume, and is therefore ideal for using GPRS.

Connection establishment is considerably faster using GPRS rather than using conventional modem technology. Field devices are often required to allow the fastest possible readout. Here GPRS has a clear advantage over other technologies.

For choosing a provider and a GPRS tariff, the following data should be carefully compared:

Any prospective subscriber will pay attention to the basic charge and the included monthly volume in choosing a provider. But just as important is the GPRS tariff unit. Since usually no connect times are billed in the GPRS network the billing is based on the amount of bytes transmitted. The billing unit used is the block size unit. In current contracts, block sizes of one kilobyte are most frequent, whereas previously block sizes of 100 kilobytes were normal. That means for the customer that always a complete block will be billed per dial-in into the GPRS network, even if the data transmitted is actually less. With a block size of 100 Kbyte, this may easily result in a high bill

 

What is GIS

GIS (Geographical Information System) is a software which consists of specially developed comprehensive and detailed maps of the city/country with latitude & longitude information of each place, street, junction and address .

GIS allows us to view, understand, question, interpret, and visualize data in many ways that reveal relationships, patterns, and trends in the form of maps, globes, reports, and charts.

A GIS helps us to answer questions and solve problems by looking at ourdata in a way that is quickly understood and easily shared.

Any organization having new and legacy data stored in a variety of formats in many locations, need a way to integrate the data so that it can be used to analyze it as a whole and leverage it to make critical business and planning decisions.

GIS can integrate and relate any data with a spatial component, regardless of the source of the data. For example, we can combine the location of mobile workers, located in real-time by GPS devices, in relation to customers' homes, located by address and derived from our customer database. GIS maps this data, giving dispatchers a visual tool to plan the best routes for mobile staff or send the closest worker to a customer. This saves tremendous time and money.