1. How GPS works?
2. How accurate is GPS?
3. Who needs GPS Receivers?

Car Navigation System

4. What are the benefits of Car Navigation System?
5. What kind of directions do the voice prompts give?
6. Two types: plug-and-play vs. in-dash
7. What is a traffic information service?

1. How GPS works?

GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. GPS receivers take this information and use triangulation to calculate the user’s exact location. Essentially, the GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. Now, with distance measurements from a few more satellites, the receiver can determine the user’s position and display it on the unit’s electronic map.

A GPS receiver must be locked on to the signal of at least three satellites to calculate a 2D position (latitude and longitude) and track movement. With four or more satellites in view, the receiver can determine the user’s 3D position (latitude, longitude and altitude). Once the user’s position has been determined, the GPS unit can calculate other information, such as speed, bearing, track, trip distance, distance to destination, sunrise and sunset time and more.

2. How accurate is GPS?

Today’s GPS receivers are extremely accurate, thanks to their parallel multi-channel design. Multi-parallel channel receivers are quick to lock onto satellites when first turned on and they maintain strong locks, even in dense foliage or urban settings with tall buildings. Certain atmospheric factors and other sources of error can affect the accuracy of GPS receivers.

Newer GPS receivers with WAAS (Wide Area Augmentation System) capability can improve accuracy to less than three meters on average. No additional equipment or fees are required to take advantage of WAAS. Users can also get better accuracy with Differential GPS (DGPS), which corrects GPS signals to within an average of three to five meters. The U.S. Coast Guard operates the most common DGPS correction service. This system consists of a network of towers that receive GPS signals and transmit a corrected signal by beacon transmitters. In order to get the corrected signal, users must have a differential beacon receiver and beacon antenna in addition to their GPS.

3. Who needs GPS Receivers?

Although the GPS system was initially created as a means of supporting the navigational and positioning requirements of the military, it has entered our personal lives and will become a more and more indispensable aid to personal navigation.
GPS receivers are currently used by:

Company personnel to get to appointments, customers, suppliers including:
Representatives, Managers, Technical staff, Customer support, Buyers, etc.
Companies to track assets, vehicles and personnel.
Off-road travelers in desert areas (e.g. Namibia), in the bushveld, swamp areas (e.g. the Okavango), mountainous areas (e.g. Drakensberg), ice and snow fields (e.g. Antarctica), unknown or newly visited areas.
All those in aviation and shipping, from pleasure trips to all commercial and military cruising, sailing and flying.
Tourists to locate their own positions in unknown areas, to find the position of their destinations, to get route from where they are to where they want to go, to avoid identified dangerous or hazardous areas.
To mark and find all those special: Fishing spots, Diving spots, Look-out points, Game-viewing spots, Adventure sport venues, and etc.
Rescuers in search-and-rescue operations
New vehicle owners with the built-in GPS receivers

Car Navigation System

4. What are the benefits of Car Navigation System?

Just for pretty fun, when you’re using a Car navigation system to guide you around a new city, you won’t worry about getting lost, which frees you up to enjoy your trip. You’ll also be able to use your car navigation system to find fun destinations, like restaurants, hotels, and tourist attractions, and useful destinations, like gas stations, banks, and even ATMs.

You’ll get plenty out of a car navigation system when you use it in your hometown, too. Many will let you program multiple destinations, so you can save time when running errands by finding the most efficient routes between them. And many give you access to subscription traffic-information services that can warn you of accidents, construction, and more along your programmed routes, which is particularly ideal if you have a long daily commute.

5. What kind of directions do the voice prompts give?

The voice output provides information on how far you must travel until your next route change, and gives spoken driving instructions - these commands simply mirror the route indicators on your navigation screen. Most systems allow you to navigate with or without voice output.

6. Two types: plug-and-play vs. in-dash

Plug-and-play
A plug-and-play navigation system offers easy mounting options, no wiring or dash modifications, and the ability to transfer it easily from one vehicle to another. The plug-and-play navigation system comes with a mounting bracket (usually with a suction cup) that you secure to the dash, console, or windshield. You then only have to plug it into the vehicle’s power port to get power. The GPS antenna is built into the device’s housing, and maps are typically preloaded into the system’s memory. The voice prompts the system uses to guide you are usually delivered over a built-in speaker. A plug-and-play device may be compact, but it usually offers impressive performance, and many offer extra features, including MP3 storage and playback.

In-dash
In-dash navigation systems are either part of or connected to an in-dash DVD player that acts as your vehicle’s stereo and includes a retractable video screen. When a navigation system is built into an in-dash DVD player, it’s no more difficult to install than a standard in-dash stereo. In-dash systems offer significantly larger screens (an average of 7”, compared to the typical 3.5” or 4” of a plug-and-play) for better map visibility. Voice prompts are delivered over your car’s speakers. Many in-dash systems feature built-in hard drives that perform the navigation functions and store the system’s maps. Others come with map DVD-ROM discs, and temporarily store relevant map and route information when you program a destination. In either case, you can listen to your CDs or the radio while the navigation system is working.

7. What is a traffic information service?

Some systems, including various plug-and-play and in-dash navigation systems, let you subscribe to a traffic-information service. These services can warn you of traffic incidents that occur along your programmed routes, including accidents, construction, planned traffic diversions, sporting events, and more. If incidents occur, you’ll usually have plenty of time to adjust your route. Some services, in certain areas, will even monitor and inform you of the average rate of traffic flow along the roads you’ll be taking.

Traffic-information services are currently available in select metropolitan areas only (although the number of coverage areas increases periodically). Several different services are available, the one you subscribe to depends on the model of navigation system you own.

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