Automotive navigation system

An automotive navigation system is part of the automobile controls or a third party add-on used to find direction in an automobile. It typically uses a satellite navigation device to get its position data which is then correlated to a position on a road. When directions are needed routing can be calculated. On the fly traffic information can be used to adjust the route.

Dead reckoning using distance data from sensors attached to the drive train, a gyroscope and an accelerometer can be used for greater reliability, as GPS signal loss and/or multi path can occur due to urban canyons or tunnels.

History

Automotive navigation systems represent a convergence of a number of diverse technologies many of which have been available for many years, but were too costly or inaccessible. Limitations such as batteries, display, and processing power had to be overcome before the product became commercially viable. Etak made an early system that used map-matching to improve on dead reckoning instrumentation. Digital map information was stored on standard cassette tapes.

• 1966: General Motors Research (GMR) was working on a non-satellite-based navigation and assistance system called DAIR (Driver Aid, Information & Routing). After initial tests GM found that it wasn't a scalable or practical way to provide navigation assistance. Decades later, however, the concept would be reborn as OnStar.
• 1980: Electronic Auto Compass with new mechanism on the Toyota Crown.
• 1981: navigation computer on the Toyota Celica. (NAVICOM).
• 1987: Toyota introduced the World's first CD-ROM-based navigation system on the Toyota Crown.
• 1990: Mazda Eunos Cosmo became the first car with built-in GPS-navigation system.
• 1991: Toyota introduced GPS car navigation on the Toyota Soarer.
• 1992: Voice assisted GPS navigation system on the Toyota Celsior.
• 1995: Oldsmobile introduced the first GPS navigation system available in a United States production car, called GuideStar.
• 1995: Device called "Mobile Assistant" or short, MASS, produced by Munich-based company ComRoad AG, won the title "Best Product in Mobile Computing" on CeBit by magazine Byte. It offered turn-by-turn navigation via wireless internet connection, with both GPS and speed sensor in the car.
• 1995: Renault Safrane introduce first European CD based navigation system (CARMINAT Philips - Renault), big color display modern interface and 2D map view.
• 1995: BMW 7 series E38 second European model with the Sat Nav, using pretty same software and hardware (Philips - Renault) like Renault Safrane, build in magnetometer, more features available from the menu like: AUX ventilation, TV or Phone
• 1997: Navigation system using Differential GPS developed as a factory-installed option on the Toyota Prius
• 1998: First DVD-based navigation system introduced on the Toyota Progres
• 2000: The United States made a more accurate GPS signal available for civilian use.
• 2003: Toyota introduced the first Hard disk drive-based navigation system and the industry's first DVD-based navigation system with a built-in Electronic throttle control
• 2007: Toyota introduced Map on Demand, a technology for distributing map updates to car navigation systems, developed as the first of its kind in the world
• 2008: World's first navigation system-linked brake assist function and Navigation system linked to Adaptive Variable Suspension System (NAVI/AI-AVS) on Toyota Crown.

Technology

The road database is a vector map. Street names or numbers and house numbers are encoded as geographic coordinates so that the user can find some desired destination by street address.
Points of interest (waypoints) are stored with their geographic coordinates. Formats are almost uniformly proprietary; there is no industry standard for satellite navigation maps, although some companies are trying to address this with SDAL and NDS.
Map data vendors such as Tele Atlas and Navteq create the base map in a Geographic Data Files format, but each electronics manufacturer compiles it in an optimized, usually proprietary format. GDF is not a CD standard for car navigation systems. GDF is used and converted onto the CD-ROM in the internal format of the navigation system.
CARiN Database Format (CDF) is a proprietary navigation map format created by Philips Car Systems (this branch was sold to Mannesman VDO, which became VDO/Dayton in 1998, then Siemens VDO in 2002, then Continental in 2007) and is used in a number of navigation-equipped vehicles. The 'CARiN' portmanteau is derived from Car Information and Navigation.
SDAL is a proprietary map format published by Navteq, who released it royalty free in the hope that it would become an industry standard for digital navigation maps. Vendors who used this format include:

• Microsoft
• Magellan
• Pioneer
• Panasonic
• Clarion
• InfoGation

The format has not been very widely adopted by the industry.

Navigation Data Standard (NDS)

The Navigation Data Standard (NDS) initiative, is an industry grouping of car manufacturers, navigation system suppliers and map data suppliers whose objective is the standardization of the data format used in car navigation systems, as well as allow a map update capability. The NDS effort began in 2004 and became a registered association in 2009. Standardization would improve interoperability, specifically by allowing the same navigation maps to be used in navigation systems from 20 manufacturers. Companies involved include BMW, Volkswagen, Daimler, Renault, ADIT, Aisin AW, Alpine Electronics, Navigon, Navis-AMS, Bosch, DENSO, Mitsubishi, Harman International Industries,Panasonic, PTV, Continental AG, Clarion, Navteq, Navinfo, TomTom and Zenrin.

Media

The road database may be stored in solid state read-only memory (ROM), optical media (CD or DVD), solid state flash memory, magnetic media (hard disk), or a combination. A common scheme is to have a base map permanently stored in ROM that can be augmented with detailed information for a region the user is interested in. A ROM is always programmed at the factory; the other media may be preprogrammed, downloaded from a CD or DVD via a computer or wireless connection (bluetooth, Wi-Fi), or directly used utilizing a card reader.
Some navigation device makers provide free map updates for their customers. These updates are often obtained from the vendor's website, which is accessed by connecting the navigation device to a PC.

Real-time data

Some systems can receive and display information on traffic congestion using either TMC, RDS, or by GPRS/3G data transmission via mobile phones.

Integration and other functions

The color LCD screens on some automotive navigation systems can also be used to display television broadcasts or DVDmovies.
A few systems integrate (or communicate) with mobile phones for hands-free talking and SMS messaging (i.e., using Bluetooth or Wi-Fi).
Automotive navigation systems can include personal information management for meetings, which can be combined with a traffic and public transport information system.

Original factory equipment

Many vehicle manufacturers offer a GPS navigation device as an option in their vehicles. Customers whose vehicles did not ship with GPS can therefore purchase and retrofit the original factory-supplied GPS unit. In some cases this can be a straightforward "plug-and-play" installation if the required wiring harness is already present in the vehicle. However, with some manufacturers, new wiring is required, making the installation more complex.
The primary benefit of this approach an integrated and factory-standard installation. Many original systems also contain a gyrocompass or accelerometer and may accept input from the vehicle's speed sensors, thereby allowing them to navigate via dead reckoning when a GPS signal is temporarily unavailable. However, the costs can be considerably higher than other options.

SMS 

Establishing points of interest in real-time and transmitting them via GSM cellular telephone networks using the Short Message Service (SMS) is referred to as Gps2sms. Some vehicles and vessels are equipped with hardware that is able to automatically send an SMS text message when a particular event happens, such as theft, anchor drift or breakdown. The receiving party (e.g., a tow truck) can store the waypoint in a computer system, draw a map indicating the location, or see it in an automotive navigation system.

GPS based control points for mapping

To carry out the infrastructural development in any area, topographical maps (accurate, reliable and updated) of that area are of vital important. Topographic maps are also important aids for administrative and strategic planning, disaster mitigation, socioeconomic development and other related activities. In order to prepare topographic map, it is prerequisite to have grid coordinates as well as elevations of control points.

GPS has already been used as an important tool for establishment of control points accurately, quickly and economically in a versatile way. Though it provides precise planimetric position of a station but it provides gross imprecision in height (Ghosh and Rao, 2001). Moreover, the coordinates of the points are obtained in the WGS 84 reference system, a global coordinate system. But, for preparation of topographic maps, cartographers are in need of grid coordinates in local (topocentric) coordinate system. To find the local coordinates from global coordinates, transformation parameters between the local and the global system are required which requires at least known three common stations. But, due to security reason, often the precise local geodetic coordinates of control points are not made available to civil users. The problem of non-availability of local geodetic coordinates can be circumvent by adopting an appropriate method.

The objective of this paper is to discuss a simple method for finding out the grid coordinates as well as elevation of control points in a topocentric coordinate system using GPS data followed by a case study implementing the method.

Methodology

To prepare a topographic map, it is a usually convenient to have grid coordinates in a topocentric coordinate system having geographic North, East and Vertical up directions as the three reference axes. In this section,
a methodology has been discussed for positioning of control points in a topocentric coordinate system with geographic North, East and Vertical up directions as the three reference axes from GPS observation (in WGS 84 – a global geocentric coordinate system). With reference to figure 1, let us consider a global geocentric coordinate system representing WGS 84 system be defined by three mutually perpendicular axes X,Y and Z. Let a topocentric coordinate system be defined by n, e and u at station P. The n axis points towards geographic North; the e axis toward East, and the u axis in vertical up direction. The axis u is along the plumb line at P and thus axes n and e are in a horizontal plane tangential to earth’s surface at P.

Let the spatial orientation of the local coordinate system with origin at P is specified by the global geodetic coordinates global

site on River Gola. It was proposed to carry out a topographic surveying and mapping of an area of about 800 meter long and 300 to 400 meter wide in the bed of Gola river. Since the duration of surveying work was limited, it was planned that area to be surveyed is divided into parcel of land across the river having over lapping in each side. It was decided that each area would be provided with control points. To obtain accurate, quickly as well as easily, control points were planned to be established through GPS. Thus, coordinates of the terrestrial points are thus obtained are in a global system. But to prepare of topographic maps, topocentric coordinates of the control points are required. The requirement was met by transformation of global coordinates into topocentric local coordinates as discussed in previous section.

 

Observation and Result

The observation was taken on December 29, 2002 starting from 09hr 31min 55sec to 16hr 46min 55sec i.e., a duration of 7 hr 15 min starting from morning to evening. On next day i.e, on December 30, 2002 the observation session started at morning (08 hr 31 min 30 sec) and continued till evening (14 hr 32min 25 sec) for a duration of 6 hr 12 min 55 sec. The observed data was processed in SKI 2.3 in relative positioning mode. Dual frequency data were used in processing. Broadcast ephemerides were used to compute the position of satellite. Hopfield model was used to take into consideration the delay caused by troposphere but no model was used for ionospheric interference. After processing the data, positions of the B.M. and other control points have been found in WGS 84 coordinate system.
The global coordinates thus found are then converted to local Cartesian Coordinates (Topocentric System) with origin at B.M. using the Equation (10). The local Cartesian Coordinates of the control points are obtained considering B.M. as origin. A plot of the planimetric position of the control points is as shown in Figure 4
.To find the vertical position of the control points two types of heights i.e., orthometric height and reduced level have been found. The concept of datum transformation (Hofmann- Wellenhoff, 2001) has been used to find orthometric height. In this, first the amount of geodetic undulation at the B.M. is calculated from geodetic height (606.794 meter, found from GPS obsevation) and the orthometric height (637.5000 meter) as established field data. This has been found to be 30.706 meter (637.500- 606.794). The reduced level (R.L.) of the control points are calculated using the R.L. of the B.M (637.5000 meter) and the difference in vertical elevation (z) between the B.M. and that of considered control point [as found by the transformation equation (10) given in Table 1, the z component]. The orthometric height and the R.L. of all the control points thus obtained are as shown in Table 1.

Discussion

To minimize the inherent errors associated with in GPS observations (Leick, 1995) due precausion had been taken all throughout the campaign. Moreover, observations were taken in relative positioning mode and the area surveyed is small thus it has been assumed that the residual error, if any, is the same for all points.

The topo-centric local grid coordinates of control points are calculated from GPS observation. A transformation matrix based on geodetic coordinates of the origin (based on GPS observation in the global geodetic system) has been used and no other data is required for finding out the planimetric positions. The vertical height of points are also found from the same GPS observation. Thus, all the three components of the position of any control point are based on same set of GPS observation. This helps in minimizing the field work drastically over the traditional methods.

The elevation of points has been found by adopting two independent methods using the same set of GPS observation. First one is the method of datum transformation. In this method, the orthometric heights of points have been found. Since, the distance between origin and other points are small with respect to geodetic consideration, it has been assumed that the difference in the angle of deflection to vertical (e) between the origin and other points is negligibly small. Next, the reduced level (vertical elevation) of control points are calculated using the vertical height (found by transformation matrix) and R.L. of B.M. These heights are found to be mostly equal to that of orthometric heights. The deviations of R.L. from orthometric heights within the study area noted to be increasing with the distance from origin (Figure 5) but do not depend on the height of points above origin (figure 6). Thus, the variation in heights may be attributed to the variation in geodetic undulation with distance, as expected since the terrain is hilly.

Further, the grid coordinates thus calculated can easily be related to other local or global network as the considered directions (north, East and vertical) of axes are universal and origin (B.M.) is well established.

Conclusion

Transformation of GPS observation will help cartographers by providing a topo-centric coordinate system with B.M. as origin. This method results in very accurate positioning of control points for a small area. This method is quite simple and easier than conventional transformation methods. Moreover, this will lead to overcome the problem of non-availability of precise geodetic coordinates of control points. Determination of vertical height of points is quite simple. However, to restrict the amount of accuracy within desired limit, the variation of geodetic undulation at the site is to found before further surveying operation. The areal extent to which the undulation deviates from that of the origin within the permissible limit (depending on the desire accuracy of the campaign) first better be determined. Thus, if area to be surveyed is large and the desired accuracy is high, a number of bench marks are required to be available in the site or to be established first and subsequently, the command area for mapping using GPS observation around the bench marks are to be found.

Surveying for Mapping — Surveying Using GPS and Conclusion

Surveying with GPS

Initially developed for military use, GPS is now part of everyday life; used in mobile phones, in-car navigation and search and rescue equipment to mention just a few.  But there is a wide variety of equipment and techniques that can be used for surveying.
This web site provided by the Smithsonian National Air and Space Museum gives more detail.

GPS was rapidly adapted for surveying, as it can give a position (Latitude, Longitude and Height) directly, without the need to measure angles and distances between intermediate points.  Survey control could now be established almost anywhere and it was only necessary to have a clear view of the sky so the signal from the GPS satellites could be received clearly.
GPS is similar in some ways to the Trilateration and EDM previously discussed, except that the known positions are now the GPS satellites (and their orbits) 20,000 km in space.  The equipment and calculations are extremely complex, but for the user the process is generally very simple.

In the commonly available receivers, the GPS receiver almost instantly works out its position (Latitude, Longitude and Height) with an uncertainty of a few metres, from the data broadcast by the satellites.  This data includes a description of the satellites changing position (its orbit) and the time the data was transmitted.

GPS Point Positioning.

GPS Baseline

The GPS receivers used for surveying are generally more complex and expensive than those used in everyday life.  They use the two frequencies broadcast by the GPS satellites and they use the physical characteristic of the GPS signal (the phase) and sophisticated calculation methods to greatly improve the accuracy of the positions obtained.  These receivers usually have a separate high-quality antenna.

A GPS baseline uses two survey-quality GPS receivers one at each end of the line to be measured . They collect data from the same GPS satellites at the same time.  The duration of these simultaneous observations varies with the length of the line and the accuracy needed, but is typically an hour or more.  When the data from both points is later combined, the difference in position (Latitude, Longitude and Height) between the two points is calculated with special software.  Many of the uncertainties of GPS positioning are minimized in these calculations because the differences between the observations at each end of the baseline are used.

The accuracy obtained from this method depends on the duration of the observations, but is typically about 1 part per million (1 millimetre per kilometre) so a difference in position can be measured over 30 kilometres with an uncertainty of about 30 mm, or about 100 mm over a 100 kilometres.  Because the GPS satellites are in a very high orbit (20,000 km) the ends of the GPS baseline can be hundreds, or even thousands of kilometres apart and still observe the same satellites. 

Although a single baseline from a known position is enough to give the position at the other end of the baseline, additional GPS baselines to other points are often measured to give a check on the results and a an estimate of the uncertainty of the calculated position.

GPS Baseline Measurement

Kinematic GPS

There are many variations on this type of GPS surveying, but basically it is similar to the GPS baseline method, except that while one GPS receiver remains on a known position (Base Station), the other moves between points and it only needs to be at each point for a few seconds.  Corrections to the GPS data (based on the known Base Station position and its position computed from the GPS) may be immediately transmitted from the receiver on the Base Station to the receiver at the other end of the line (the remote station).  The position of the remote station can then be computed and stored, all within a few seconds.  Radios or mobile phones can be used to transmit the corrections.  Although this method can give similar accuracy to the baseline method previously described, to do so this method is generally limited to a distance of about 20 kilometres.

GPS Real-Time Baseline Measurements

Continuously Operating Reference Stations (CORS)

A survey-quality GPS receiver may be permanently installed in a convenient location with a known position, to be used as the starting point for any GPS measurements in the district.  This could be for a project such as a mine site or major engineering project, or in a town for local government use.

One or several survey quality GPS receivers can then be used to simultaneously collect GPS data at any required points and the data later combined with the GPS data obtained from the Continuously Operating Reference Station (CORS) to calculate the positions.  If there are more than one CORS available, the unknown position can be calculated with respect to these multiple known positions, giving more confidence in the results.  The duration of the observations depends on the distance from the CORS, but typically it is an hour or two.

Many countries have a CORS network which covers the entire nation, allowing accurate GPS positioning anywhere in their country.  CORS usually also contribute data to global observations that make the GPS system more reliable and accurate.  They also provide data for scientific studies such as plate tectonics and meteorology.  To be useful for the study of tectonics, the permanent marks used for the CORS stations must be geologically stable, and the observations should be continuous and for many years.

Australia's national CORS network, the Australian Regional GPS Network (ARGN) may be used with the on-line processing system AUSPOS, that allows GPS data from a survey quality GPS receiver to be submitted via the Internet and have the calculated position emailed back, typically in a few hours.  The calculations used to produce these positions use more accurate satellite orbits and within about 24 hours of observation can give a position anywhere in Australia with an uncertainty of a few centimetres.

 

A GPS CORS network

Heights from GPS

Because it is a three-dimensional system, GPS automatically gives height as well as Latitude and Longitude. But the height is above the theoretical surface of the Earth used for the calculations, known as the ellipsoid (so the height is called an ellipsoidal height) not above Mean Sea Level. More information on this subject is available in the Datums 1 and Datums 2 sections.The difference between an ellipsoidal height and a MSL height can be large (up to 100 metres) and irregular because of the varying density of the earth. Fortunately it is well understood and the difference is routinely applied by most GPS software. To do this, the difference between the ellipsoid and a surface of equal gravity, known as the Geoid is used.

Although the Australian Height Datum, Mean Sea Level and the Geoid may be considered the same for most practical purposes, the differences are taken into account for the most accurate applications.Most GPS positions are based on the GPS satellites’ orbits which are transmitted with the data at the time of observation (Broadcast orbits). These orbits are predicted from previous observations at global monitoring stations. For the most accurate positions with GPS, the computations are done much later and use more accurate GPS satellite orbits that are based on observations at global monitoring stations at the time of the original measurement.

Adjustment of Surveying Measurement for Heights

Most of the surveying methods described produce more than the minimum number of observations needed to calculate positions or heights.  So it is possible for a position or height to be calculated by several paths through the network of observations and get slightly different results because of the uncertainties in the survey observations.  To resolve this, all observations are usually combined into a mathematical process which produces the best position for each point along with an estimate of the uncertainty.  This process is known as a Least Squares adjustment.

Ten Things You Need to Know About GPS

1) Definition: Global Positioning System

The Global Positioning System refers to a constellation of 24 satellites (plus some “hot spares” for when one fails) put into space by the U.S. Department of Defense to help locate stationary and moving features on or near the Earth’s surface. The satellites send out radio signals that receivers use to determine position, velocity and time. 

2) The Generic Term for Such a System is GNSS

GPS, while used generically, refers only the U.S. constellation of satellites. The generic term for these systems is Global Navigation Satellite System, GNSS. Among those are existing systems such as Russia’s GLONASS, and in-development solutions including the European Union’s Galileo and China’s COMPASS. India, France and Japan are building regional systems.

1. GLONASS - Wikipedia, the free encyclopedia
2. Galileo (satellite navigation) - Wikipedia, the free encyclopedia
3. Beidou navigation system - Wikipedia, the free encyclopedia.

3) How GNSS Works

All of these systems work in roughly the same way. The satellites orbit around earth and broadcast information. That information is basically a time stamp. A receiver (a computer built to listen for signals and do math on the data received) collects the time stamps from four satellites and compares them with the current time. By knowing where each satellite is in space and how long each signal took to travel to earth, the receiver can determine its location on the earth’s surface. 

4) GNSS Receivers Receive

GNSS receivers are designed to receive GNSS signals and process them into location information. The devices fall into three categories for different uses and price points. As you move from recreational to survey grade accuracy goes up, as does price: 

1. recreational/consumer grade
2. mapping grade
3. survey grade

GNSS receivers may also have functions that can turn a location into a point on a map stored on the device, determine speed, direction and other derived measurements. However, unless the receiver also has a transmitter of some kind (like a cell phone does), the data remain on the device. In particular, GNSS receivers do not have two-way communication with the navigation satellites; the satellites are broadcast-only.

5) GNSS is not Great at Elevation

Horizontal (location) accuracy of GNSS devices is still far higher than vertical (elevation) accuracy. Horizontal accuracy for recreational/consumer devices and many cell phones is about +/- 10 meters (within a tennis court) while vertical accuracy can be two or three times that, about +/- 20 or 30 meters.

The reason vertical accuracy is relatively poor relates to geometry. When you look up at the sky, if you had Superman eyesight you would see GNSS satellites all around. That supports accurate horizontal positioning. However, when you look out horizontally, out at the horizon, you can only see satellites in front of and above you, not below, since the earth gets in the way. It’s the lack of signals coming from beneath you that results in the lower quality of altitude measures.

If you need to capture accurate vertical data, you may want to look at other measurement tools to complement your GNSS-captured horizontal data.

6) GNSS Systems Work Together and with Other Positioning Device

With multiple GNSSs online, or coming online, and a variety of non-GPS locating technologies in use (wi-fi, cell tower, etc.), there’s an effort to bring them together for enhanced solutions. Hardware developers are building chips that receive signals from two or more satellite constellations, while software developers are finding new ways to tap into the variety of locating technologies for use in different environments (indoor/outdoor/underground) and situations.

7) GPS Interference

Because GPS signals from satellites are very weak radio signals, they are susceptible to interference by natural and man-made signals. The former include signals resulting from solar storms and the latter, from other radio frequency-based projects including GPS “jammers” (illegal in the United States). In 2011/2012 concerns rose regarding GPS interference by a proposed wireless service from a company called LightSquared. The FCC has decided not to let this company move forward with its network at this time. 

8) Government Control of GPS

While the U.S. Department of Defense developed and operates GPS, it serves a wide range of civilian users from surveyors, to mappers, to hikers, to vacationers geotagging photographs on their cell phones. To date, the Department of Defense has never “shut off” GPS in any part of the world, for any reason.

9) Navigating by GNSS

GNSS receivers are sometimes referred to as satnavs, that is, as satellite navigation devices. The GNSS only provides information to a receiver to determine its current location, velocity and time. Any other information, such as the direction of motion, a suggested route to a destination, a map, is provided by software algorithms and map data stored on a hand-held device or accessible on a server. Said another way, GNSS satellites do not provide directions or maps.

10) The GPS is Worng!

Most of the time a GPS receiver is correct in determining its position, within its tolerance. If a navigation system fails to provide an accurate route, other things are more likely to be the culprit, for example:

1. poor algorithm
2. out-of-date street network
3. wrong destination address

The U.S. government received so many complaints on this matter it compiled an article to explain to users how to “fix” such errors.

Advantages and Disadvantages Global Positioning System

GPS stands for global positioning system which was created by US department of defense for the navigation of military in any part of world under circumstances. But with the time, this system is now being used for many other purposes and GPS system has proved to be a revolutionary technology in today's world. There are several advantages of GPS at present and in contrast to that there are some disadvantages also. Some of them are:

Disadvantages of Global Positioning System:

1. Sometimes the GPS may fail due to certain reasons and in that case you need to carry a backup map and directions.
2. If you are using GPS on a battery operated device, there may be a battery failure and you may need a external power supply which is not always possible.
3. Sometimes the GPS signals are not accurate due to some obstacles to the signals such as buildings, trees and sometimes by extreme atmospheric conditions such as geomagnetic storms.

Advantages of GPS:

1. GPS is extremely easy to navigate as it tells you to the direction for each turns you take or you have to take to reach to your destination.
2. GPS works in all weather so you need not to worry of the climate as in other navigating devices.
3. The GPS costs you very low in comparison other navigation systems.
4. The most attractive feature of this system is its100% coverage on the planet.
5. It also helps you to search the nearby restaurants,HOTELS AND gas stations and is very useful for a new place.
6. Due to its low cost, it is very easy to integrate into other technologies like cell phone.
7. The system is updated regularly by the US government and hence is very advance.
8. This is the best navigating system in water as in larger water bodies we are often misled due to lack of proper directions.

Some more Advantages about GPS:-

Directions

A device taking advantage of GPS is equipped with maps and locations from around the world. Smartphones and tablet PCs are able to pinpoint a location and provide accurate step-by-step directions from Point A to Point B. If you make a wrong turn, devices like these will provide an updated route based on your new location. They can save you a considerable amount of time navigating foreign areas, finding a local restaurant or locating the nearest emergency service facility.

Avoiding Traffic

Devices that use GPS receive real-time updates, allowing them to monitor traffic and re-direct you to a faster, more efficient route. In some instances, it can provide you with traffic flow information so you can assess for yourself whether a specific route is worth the expected traffic. Both TomTom and Garmin produce models that feature frequently updated traffic information. Models that include the letter T in their names are generally receiving traffic updates.

Crime Prevention 

Law enforcement is finding numerous uses for GPS technology. Some law enforcement agencies have used GPS devices to monitor vehicles and individuals suspected of a criminal or terrorist activity. By doing so, law enforcement officials have prevented heinous crimes and caught criminals that would have otherwise gotten away. According to the Congressional Research Service, law enforcement used GPS to catch a convicted rapist who had served 17 years in prison. The man was a suspect in 11 attacks on women in Virginia over a six-month period, and authorities attached a GPS device to his van. "By tracking his movements with the device, police were able to intercept him in Falls Church, VA, where he was dragging a woman to a remote area, according to the report." The ability to stop criminals in their tracks, before further crime is committed, makes GPS technology valuable to law enforcement officers.

Emergency Relief 

During a tornado, hurricane or other natural disaster, emergency services and law enforcement officials need to find stranded motorists. GPS technology provides tracking information and helps predict the natural disaster’s damage severity for emergency relief. With GPS, ambulances and law enforcement officers track and locate victims of natural disasters quickly and efficiently.

Construction and Development

Before construction and development can begin, land surveying must be completed. This is costly and time-consuming and requires a variety of individuals. The GPS has slowly replaced traditional land surveying techniques with the Federal Highway Administration for more accurate surveying. By using GPS, companies have reduced labor costs and increased accuracy and survey an area in a matter of a few hours – rather than days. 
For parents, it takes some of the worry out of your kids driving long distances home from college. You know where they are and when to expect them home.

• For parents of teenagers, you never have to wonder if your son or daughter is where they say they are. No more late night phone calls asking – “Where are you?”

• For baby-boomers, the shoe is on the other foot - it helps to take some of the worry out of your elderly parents driving home from vacation or just driving around town. You know where they are and this allows them to be more independent.

• GPS tracking is customer service at it’s finest. You know instantly which of your drivers is closest to the customer needing help.

• Imagine how thrilled your customers will be when you can tell them exactly when to expect their delivery!

• For employers, using GPS tracking allows you to know how fast your employees are driving, how long a break they are taking (vehicle hasn’t moved), and if they are where they say they are!

• GPS tracking also allows you to monitor fuel usage based on how fast your employee is driving and the automatic mileage feature reminds you to schedule, regular preventative maintenance.

• GPS tracking is customer service at it’s finest! You know instantly which of your drivers is closest to the customer needing help. And Imagine how thrilled your customers will be when you can tell them exactly when to expect their delivery!

• GPS Tracking can eliminate the need for having your truckers fill out driving logs.

• Many insurance companies now offer discounts for vehicles protected with tracking systems.

Personal navigation assistant

A Personal Navigation Assistant (PNA) also known as Personal Navigation Device or Portable Navigation Device (PND) is a portable electronic product which combines a positioning capability (such as GPS) and navigation functions. Some PNA devices are PDAs with limited features and can be unlocked.

History  

The earliest PNAs were hand-held GPS units (circa mid-1980s) which were capable of displaying the user's location on an electronic map. These units included simple navigation functions such as course-to-steer and course-made-good. This first generation of PNAs were used by the US military.

Market developments

According to the analyst firm Berg Insight, there were more than 150 million turn-by-turn navigation systems worldwide in mid-2009, including about 35 million factory installed and aftermarket in-dash navigation systems, over 90 million Personal Navigation Devices (PNDs) and an estimated 28 million navigation-enabled mobile handsets with GPS.
The term PNA has come into widespread use with the growing popularity of automobile navigation systems. Original PNAs provided users with a map layer, real-time-traffic, and a routing engine with audio/visual cues for turn-by-turn guidance. The latest generation of PNA have sophisticated navigation functions such as parking assistance and personalization engines that enhance the user experience. To reduce total cost of ownership and time to market, most modern PNA devices such as those made by Garmin Ltd., Mio Technology Ltd. or TomTom International BV. are running an off-the-shelf embedded operating system such as Windows CE or Embedded Linux on commodity hardware with OEM versions of popular PDA Navigation software packages such as TomTom Navigator, I-GO 2006, Netropa IntelliNav iGuidance, or Destinator.
Other manufacturers such as Garmin and Magellan prefer to bundle their own software developed in-house. Because many of these devices use an embedded OS, many technically inclined users find it easy to modify PNAs to run third party software and use them for things other than navigation, such as a low-cost audio-video player or PDA replacement.
GPS equipped mobile phones have now eclipsed the sale of dedicated GPS units. Nokia, Samsung Electronics, Motorola and other handset makers were predicted to sell sell 162 million GPS equipped phones in 2007, dwarfing the 20 million units Garmin and TomTom have forecast they will sell combined, according to iSuppli, a leading market researcher in California. The inclusion of Google Maps Navigation in Android devices such as Motorola Droid and Nokia's announcement of free Ovi Maps has led to many people using their smartphones instead of having a separate PNA for trip navigation.

Personal digital assistant

A personal digital assistant (PDA), also known as a handheld PC, or personal data assistant, is a mobile device that functions as a personal information manager. The term evolved from Personal Desktop Assistant, a software term for an application that prompts or prods the user of a computer with suggestions or provides quick reference to contacts and other lists. PDAs were largely discontinued in the early 2010s after the widespread adoption of highly capable smartphones, in particular those based on iOS and Android.
Nearly all PDAs have the ability to connect to the Internet. A PDA has an electronic visual display, enabling it to include a web browser, all models also have audio capabilities enabling use as a portable media player, and also enabling most of them to be used as mobile phones. Most PDAs can access the Internet, intranets or extranets via Wi-Fi or Wireless Wide Area Networks. Most PDAs employ touchscreen technology.
The first PDA was released in 1984 by Psion, the Organizer. Followed by Psion's Series 3, in 1991, which began to resemble the more familiar PDA style. It also had a full keyboard. The term PDA was first used on January 7, 1992 by Apple Computer CEO John Sculley at the Consumer Electronics Show in Las Vegas, Nevada, referring to the Apple Newton. In 1994, IBM introduced the first PDA with full mobile phone functionality, the IBM Simon, which can also be considered the first smartphone. Then in 1996, Nokia introduced a PDA with full mobile phone functionality, the 9000 Communicator, which became the world's best-selling PDA. The Communicator spawned a new category of PDAs: the "PDA phone", now called "smartphone". Another early entrant in this market was Palm, with a line of PDA products which began in March 1996. The terms "personal digital assistant" and "PDA" apply to smartphones but are not used in marketing, media, or general conversation to refer to devices such as the BlackBerry, iPad, iPhone or Android devices.

Typical features

A typical PDA has a touchscreen for entering data, a memory card slot for data storage, and IrDA, Bluetooth and/or Wi-Fi. However, some PDAs may not have a touch screen, using softkeys, a directional pad, and a numeric keypad or a thumb keyboard for input; this is typically seen on telephones that are incidentally PDAs.
In order to have the functions expected of a PDA, a device's software typically includes an appointment calendar, a to-do list, an address book for contacts, a calculator, and some sort of memo (or "note") program. PDAs with wireless data connections also typically include an email client and a Web browser.

1. Touch screen

2. Memory cards

3. Wired connectivity

4. Wireless connectivity

5. Synchronization

Automobile navigation

Some PDAs include Global Positioning System (GPS) receivers; this is particularly true of smartphones. Other PDAs are compatible with external GPS-receiver add-ons that use the PDA's processor and screen to display location information.

PDAs with GPS functionality can be used for automotive navigation. PDAs are increasingly being fitted as standard on new cars.

PDA-based GPS can also display traffic conditions, perform dynamic routing, and show known locations of roadside mobile radar guns. TomTom, Garmin, and iGO offer GPS navigation software for PDAs.

 

 

 

 

 

 

 

Difference Between GPS and GPRS

GPS vs. GPRS

Although there is only one letter separating GPS and GPRS, they are worlds apart when you examine their technology and functions. GPS is a positioning service that can determine any location on earth, through a process called transliteration, hence the name Global Positioning System. On the other hand, GPRS is a data service techn

ology that enables 2G telecommunication networks to provide services other than voice calls. These services include access to email, multimedia messaging, and a somewhat limited access to the internet.

As stated above, GPS and GPRS play specific roles, and are not compete technologies. GPS is an old military technology that is now beginning to mature in the market, since it was not that long ago when full civilian access was given by the US government. Full access allowed receivers to pinpoint their location within 10 feet, making it a viable tracking tool for location and navigation devices used in planes, boats, and its most popular use nowadays, cars. The accuracy allows the navigation devices to give you real time directions. GPRS is a part of the 2G technologies, and is rather old. In most parts of the developed world, GPRS has been replaced by superior 3G technology. It can be thought of as the dial-up equivalent for mobile phones.

The workings of both also differ significantly, as GPS receives information from satellites on low earth orbit, while GPRS communicates with terrestrial cellular towers. GPRS needs just one cell tower with adequate signal in order to work properly. GPS, on the other hand, needs three or more satellites due to basic principles of transliteration. Due to the extreme height of the orbiting satellites, you can use your GPS device just about anywhere in the world, even in the middle of the Pacific Ocean. GPRS is limited to cellular towers located on land.

 

 

 

 

 

 

 

  

GPS

GPS, or Global Positioning System, is a navigation system for portable devices. It uses a network of satellites surrounding the planet. A compatible device such as a smartphone or a dedicated navigation device has a built-in receiver chip that picks regular up signals from these satellites. Each signal is time-coded so the device can calculate how far away it is from the satellite based on the time the signal takes to arrive. By combining the distances from at least four satellites, the device can calculate its position to within a few feet. It can also cross-reference this with map data to provide navigation such as driving directions.

GPS Alternatives

Not all phones have a GPS receiver, but those that do not may still offer navigation tools. One method is using cellular triangulation which works in a similar way to GPS but using signals from cellphone towers rather than satellites. Because the towers are nearer only three signals are needed to calculate a location, although the resulting location is not as precise. Another method is scanning for nearby Wi-Fi networks and checking their IP address against a database of known networks to find the location. This method is the least reliable and gives even less precise positioning.

GPRS

GPRS, or General Packet Radio Service, is the standard technology used for data transfers on all but the latest cellphones. It was introduced with the first digital handsets and is also known as 2G, or "Edge" (which is why you may recall seeing an "E" near your signal bars) and continues to be used with handsets supporting faster connections, known as 3G. GPRS is the sister technology of GSM (Global System for Mobile Communications) which is used for voice calls. The key to GPRS is that it breaks data into small pieces known as packets. If there is a problem with the connection, the receiving device can issue a request for the missing packets to be resent without the need to start the entire data transmission again. This mirrors the way data transfers over the Internet.

GPRS Alternatives

Newer handsets may run one of two technologies for even faster data transfer, known as 4G. These are called WiMAX (Worldwide Interoperability for Microwave Access) and LTE (Long Term Evolution). They work by using different systems for encoding and transmitting data to make more efficient use of the available bandwidth. 4G services can work for both cellphones and computer devices and aim to give similar performance to wired broadband services in the home. 4G requires a specially built cellphone network which means that as of October 2012 it is much less widely available than GPRS-based services.