ASSIGNMENT-#3
GPS
What is GPS??
Originally conceived as a navigation aid, Global Positioning System, or GPS, has since grown from relatively humble beginnings as different supporting technologies have been developed which fall into consumer budgets.
All that GPS does is provide a set of coordinates which represent the location of the GPS unit with respect to it’s latitude, longitude and elevation on planet Earth. It also provides an accurate co-ordinate time, which is usually as accurate as an atomic clock.
The actual application of GPS is what leads to navigation systems, GPS tracking devices and navigation using GPS mapping. GPS in itself does not provide any functionality beyond being able to receive satellite signals and calculate position information.
If Navigation stands for "determining of position and direction on or near the surface of the Earth", than GPS Navigation stands for the same with the help of the Global Positioning System (GPS). A GPS chip is a small radio-receiver that can capture the signals of several GPS satellites simultaneously. This way it can compute its Position, Velocity and the exact Time.
How it Works
The actual theory behind GPS is very easy to appreciate, since it is exactly the same as traditional triangulation. If one imagines an orienteer needing to locate themselves on a map, they first need to be able to find at least three points that they recognize in the real world, and pinpoint their locations on the map.
They can then measure, using a compass, the heading that would be needed to take them from the point on the map to their current position. A line is then drawn from each of the three points, and where the three lines meet is where they are on the map.
Translating this into the GPS world, we can replace the known points with satellites, and the direction with time taken for a signal to travel from each of the known points to the GPS receiver. This enables the system to work out roughly where it is located – it is where the circles representing the distance from the satellite, calculated on the basis of the travel time of the signal, intersect.
Of course, this requires that the GPS locator has the same coordinated time as the satellites, which have atomic clocks on board. To do this, it cross checks the intersection of the three circles with a fourth which it acquires from another satellite.
If the four circles no longer intersect at the same point, then the GPS system knows that there is an error in it’s clock, and can adjust it by finding one common value (one second, half a second and so on) that can be applied to the three initial signals which would bring the circles to intersect in the same place.
Behind the scenes, there are also many complex calculations taking place which enable the system to compensate for atmospheric distortion of the signals, and so forth, but the principle remains the same.
Tracking Devices
One of the easiest applications to consider is the simple GPS tracking device; which combines the possibility to locate itself with associated technologies such as radio transmission and telephony.
Tracking is useful because it enables a central point to monitor the position of several vehicles or people, in real time, without them needing to relay that information explicitly. This can include children, criminals, police and emergency vehicles or military applications.
The tracing devices themselves come in various different flavors. They will always contain a GPS receiver, and some GPS software, along with some way of transmitting the resulting coordinates. GPS watches, for example, tend to use radio waves to transmit their location to a tracking center, while GPS phones use existing cell phone technology.
The tracking center can then use that information for co-ordination or alert services. One application in the field is to allow anxious parents to locate their children by calling the tracking station – mainly for their peace of mind.
GPS vehicle tracking is also used to locate stolen cars, or provide services to the driver such as locating the nearest gas station. Police can also benefit from using GPS tracing devices to ensure that parolees do not violate curfew, and to locate them if they do.
Navigation Systems
Once we know our location, we can, of course, find out where we are on a map, and GPS mapping and navigation is perhaps the most well-known of all the applications of GPS. Using the GPS coordinates, appropriate software can perform all manner of tasks, from locating the unit, to finding a route from A to B, or dynamically selecting the best route in real time.
These systems need to work with map data, which does not form part of the GPS system, but is one of the associated technologies that we spoke of in the introduction to this article. The availability of high powered computers in small, portable packages has lead to a variety of solutions which combines maps with location information to enable the user to navigate.
The first such application was the car navigation system, which allows drivers to receive navigation instructions without taking their eyes off the road, via voice commands. Usually, these systems take their map data from a CD which can be replaced when the driver moves from one geographical location to another.
Then there are handheld GPS units, such as those from Garmin, which are commonly used by those involved in outdoor pursuits, and only relay very limited information such as the location, and possibly store GPS waypoints. A waypoint being a location that is kept in memory so that the unit can retrace the path at a later time.
More advanced versions include aviation GPS systems, which offer specific features for those flying aircraft, and marine GPS systems which offer information pertaining to marine channels, and tide times.
These last two require maps and mapping software which differ vastly from traditional GPS solutions, and as such can often be augmented with other packages designed to allow the user to import paper maps or charts. The mapsource software is one such industry standard package.
GPS
What is GPS??
Originally conceived as a navigation aid, Global Positioning System, or GPS, has since grown from relatively humble beginnings as different supporting technologies have been developed which fall into consumer budgets.
All that GPS does is provide a set of coordinates which represent the location of the GPS unit with respect to it’s latitude, longitude and elevation on planet Earth. It also provides an accurate co-ordinate time, which is usually as accurate as an atomic clock.
The actual application of GPS is what leads to navigation systems, GPS tracking devices and navigation using GPS mapping. GPS in itself does not provide any functionality beyond being able to receive satellite signals and calculate position information.
If Navigation stands for "determining of position and direction on or near the surface of the Earth", than GPS Navigation stands for the same with the help of the Global Positioning System (GPS). A GPS chip is a small radio-receiver that can capture the signals of several GPS satellites simultaneously. This way it can compute its Position, Velocity and the exact Time.
How it Works
The actual theory behind GPS is very easy to appreciate, since it is exactly the same as traditional triangulation. If one imagines an orienteer needing to locate themselves on a map, they first need to be able to find at least three points that they recognize in the real world, and pinpoint their locations on the map.
They can then measure, using a compass, the heading that would be needed to take them from the point on the map to their current position. A line is then drawn from each of the three points, and where the three lines meet is where they are on the map.
Translating this into the GPS world, we can replace the known points with satellites, and the direction with time taken for a signal to travel from each of the known points to the GPS receiver. This enables the system to work out roughly where it is located – it is where the circles representing the distance from the satellite, calculated on the basis of the travel time of the signal, intersect.
Of course, this requires that the GPS locator has the same coordinated time as the satellites, which have atomic clocks on board. To do this, it cross checks the intersection of the three circles with a fourth which it acquires from another satellite.
If the four circles no longer intersect at the same point, then the GPS system knows that there is an error in it’s clock, and can adjust it by finding one common value (one second, half a second and so on) that can be applied to the three initial signals which would bring the circles to intersect in the same place.
Behind the scenes, there are also many complex calculations taking place which enable the system to compensate for atmospheric distortion of the signals, and so forth, but the principle remains the same.
Tracking Devices
One of the easiest applications to consider is the simple GPS tracking device; which combines the possibility to locate itself with associated technologies such as radio transmission and telephony.
Tracking is useful because it enables a central point to monitor the position of several vehicles or people, in real time, without them needing to relay that information explicitly. This can include children, criminals, police and emergency vehicles or military applications.
The tracing devices themselves come in various different flavors. They will always contain a GPS receiver, and some GPS software, along with some way of transmitting the resulting coordinates. GPS watches, for example, tend to use radio waves to transmit their location to a tracking center, while GPS phones use existing cell phone technology.
The tracking center can then use that information for co-ordination or alert services. One application in the field is to allow anxious parents to locate their children by calling the tracking station – mainly for their peace of mind.
GPS vehicle tracking is also used to locate stolen cars, or provide services to the driver such as locating the nearest gas station. Police can also benefit from using GPS tracing devices to ensure that parolees do not violate curfew, and to locate them if they do.
Navigation Systems
Once we know our location, we can, of course, find out where we are on a map, and GPS mapping and navigation is perhaps the most well-known of all the applications of GPS. Using the GPS coordinates, appropriate software can perform all manner of tasks, from locating the unit, to finding a route from A to B, or dynamically selecting the best route in real time.
These systems need to work with map data, which does not form part of the GPS system, but is one of the associated technologies that we spoke of in the introduction to this article. The availability of high powered computers in small, portable packages has lead to a variety of solutions which combines maps with location information to enable the user to navigate.
The first such application was the car navigation system, which allows drivers to receive navigation instructions without taking their eyes off the road, via voice commands. Usually, these systems take their map data from a CD which can be replaced when the driver moves from one geographical location to another.
Then there are handheld GPS units, such as those from Garmin, which are commonly used by those involved in outdoor pursuits, and only relay very limited information such as the location, and possibly store GPS waypoints. A waypoint being a location that is kept in memory so that the unit can retrace the path at a later time.
More advanced versions include aviation GPS systems, which offer specific features for those flying aircraft, and marine GPS systems which offer information pertaining to marine channels, and tide times.
These last two require maps and mapping software which differ vastly from traditional GPS solutions, and as such can often be augmented with other packages designed to allow the user to import paper maps or charts. The mapsource software is one such industry standard package.
