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Tracking
The Global Positioning System
The Global Positioning System (GPS) is a global navigation satellite system (GNSS) developed by the United States Department of Defense and managed by the United States Air Force 50th Space Wing. It is the only fully functional GNSS in the world can be used freely by anyone, anywhere, and is often used by civilians for navigation purposes. It uses a constellation of between 24 and 32medium Earth orbit satellites that transmit precise radiowave signals, which allow GPS receivers to determine their current location, the time, and their velocity. Its official name is NAVSTAR GPS.
Since it became fully operational on April 27, 1995, GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, scientific uses, tracking and surveillance, and hobbies such as geocaching. Also, the precise time reference is used in many applications including the scientific study of earthquakes and as a required time synchronization method for cellular network protocols such as the IS-95 standard for CDMA.
Tracking is the ability to make available to a user the location of an asset : vehicle or person typically by using GPS for location. This may be coupled with a communication device (RF, GSM, GPRS) to beam the location co-ordinates back.
Tracking is not to be confused with Navigation, which tells a user where s/he is typically on an electronic device with adequate display. Navigation does not require communication ability.
Both use GPS capability, though in different forms.
Basic concept of GPS
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* A visual example of the GPS constellation in motion with the
Earth rotating. Notice how the number of satellites in view from a given point on the Earth's surface, in this example
at 45°N,changes with time.
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A GPS receiver calculates its position by precisely timing the signals sent by the GPS satellites high above the Earth. Each satellite continually transmits messages containing the time the message was sent, precise orbital information (the ephemeris), and the general system health and rough orbits of all GPS satellites (the almanac). The receiver measures the transit time of each message and computes the distance to each satellite. Geometric trilateration is used to combine these distances with the location of the satellites to determine the receiver's location. The position is displayed, perhaps with a moving map display or latitude and longitude; elevation information may be included. Many GPS units also show derived information such as direction and speed, calculated from position changes.It might seem three satellites are enough to solve for position, since space has three dimensions. However, even a very small clock error multiplied by the very large speed of light?the speed at which satellite signals propagate?results in a large positional error. Therefore receivers use four or more satellites to solve for x, y, z, and t, which is used to correct the receiver's clock. While most GPS applications use the computed location only and effectively hide the very accurately computed time, it is used in a few specialized GPS applications such as time transfer, traffic signal timing, and synchronization of cell phone base stations. Although four satellites are required for normal operation, fewer apply in special cases. If one variable is already known (for example, a ship or plane may have known elevation), a receiver can determine its position using only three satellites. Some GPS receivers may use additional clues or assumptions (such as reusing the last known altitude, dead reckoning, inertial navigation, or including information from the vehicle computer) to give a degraded position when fewer than four satellites are visible.
Tracking Methods
Logging :
A GPS device records the latitude/longitude data at periodic intervals. After a significant time interval, the data is retrieved and viewed on a PC.
Store And Forward :
GPS device records the data in memory at periodic intervals. At predefined intervals the system transmits the data using GSM/SMS.
Real Time:
The device sends the data as it is received using RF or GPRS and the user can view the location on a near real time basis.
Forms Of Real Time Tracking:
GPS And GSM/GPRS
A GPS Hardware has to be mounted on Assets to be tracked. The device is powered by a vehicle battery and it periodically communicates the data to central server using SMS, RF or GPRS. Location accuracy with GPS is 10 meters.
Cell Id Tracking
With the new generation Smart Phones, a person can be tracked without any other hardware. An application on the phone transmits the details of the current cell tower that serves the mobile device. From this, the mobile's location can be estimated. Location accuracy is better than 200 meters.
On the road with Propellex
Once a truck gets out on the road, anything can happen. To deal with the unexpected, Indian companies are deploying automated vehicle locator systems. Fully loaded cash vans, deployed to load cash in ATMs, always face the risk of being robbed.
Finding the way
Uncertainty regarding goods in transit is a big factor. Although every logistics environment has a clear workflow in place, when delays occur, they are usually due to factors that are beyond a manager?s control. Consider this. A logistics manager of a FMCG company dispatches a truck from Mumbai carrying five tons of soap to its Pune warehouse. En route the truck has an accident. The logistics manager realizes something has gone wrong only when the client says that the vehicle has not reached. If VTS system is onboard, the location of the vehicle can be pinpointed immediately and accurately. And in the case of expensive stuff like oil or gas, the risk is higher.
GIS + GPS = Propellex
In a business where delivering goods on time is critical, VTS systems are being used to manage logistics requirements. Typically, AVL systems give a real-time view of the exact route of the vehicle in addition to dispatch status by using a combination of GIS (Geographic Information System) and GPS (Global Positioning System). A vehicle's location can be determined and it can be rerouted if necessary to provide timely delivery to a nearby customer. Additionally VTS systems can help solve problems such as pilferage or trucks being held up due to non-payment of Octroi.Every vehicle is fitted with a mobile radio receiver, a GPS receiver, modem and antenna, which connect to a base radio consisting of a PC and a GPS receiver and interface. The GIS is integrated with the GPS, where the data, after being exported to a GIS can be viewed on a digital map of the area being traversed by the vehicle. The use of GIS helps in knowing the route taken by a vehicle.For a logistics manager, a simple Web interface provides the vehicle's route. A user logging on to our website has a password that lets him track the vehicle online. Any company wanting to adopt this system is charged on a per vehicle basis including all the equipment fitted in the vehicle.
A Long Way To Go
These are still early days for VTS in India. The primary reason for this is that GPS devices that are attached to vehicles are quite expensive. Since a typical VTS system is a combination of GIS, GPS and cellular technology, the growth of this market is directly dependent on development in related areas. As the level of adoption grows, prices are likely to come down. As of now we see that customers are willing to deploy this device only in select vehicles.
Another big obstacle is the nature of Indian cellular networks. The telecom sector is divided into circles and there are different players for each network and this increases the complexity of data transmission from a moving vehicle. It also restricts the operational capabilities of a system when the vehicle moves from one telecom circle to another.
Rising awareness about the use of GIS and GPS coupled with the need to spruce up service levels due to competition is likely to propel demand for VTS solutions.
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Do you worry about the whereabouts of your vehicles/goods?
