Best buy Gps Navigator Price

HOW GPS
Author: GPS_BLASTER
Modified on 11/05/2009

The GPS or Global Positioning System, Global Positioning System, is a sophisticated guidance and navigation system whose operation is based on the receipt and processing of information released by a constellation of 24 satellites known as NAVSTAR, orbiting at different altitudes to 20,000 km. above the surface. Each satellite provides two flights daily to the planet, one every twelve hours. The trajectories and orbital velocity is calculated to form a sort of net around the earth (all times must have five satellites in sight in any area), so a GPS receiver at any time of day or night , anywhere, regardless of weather conditions, may facilitate the position to capture and process the signals from at least three satellites. In the 80s the U.S. Navy implemented a navigation system based on emissions of a small group of satellites. This system called SATNAV was the antecedent of the current GPS. The GPS was developed by the U.S. Department of Defense at the end of the Cold War for military purposes. Having passed this stage, extended its use to civilian applications beginning to be used in maritime and aviation. In its early coverage was not complete because there is no place several satellites in orbit, plus the high price put them out of reach of most potential users. Currently the network is fully operational, including spare satellites and is commercially available GPS receivers at an affordable price. Evolution is constant and every day are small and lightweight ms while offering superior performance and greater operational autonomy of operation when fed with batteries. How GPS works? Each GPS satellite constellation continuously emit two codes of different data in digital format. These data are transmitted via radio signals. One of the codes is reserved for military use only and can not be captured by civilian GPS receivers. The other code, (civilian) transmits two sets of data and ephemeris known as ALMANAC. The data provided by the almanac and ephemeris report on the operational status of operation of the satellite, its orbital location, date and time. Obviously each satellite broadcasts its own ephemeris and almanac that include a specific identification code for each satellite. The satellites are equipped with atomic clocks to ensure almost complete accuracy, providing an estimated error in one second every 70,000 years. A GPS receiver must have in its report of the almanac and ephemeris updates (if they are not updated automatically in a short time n, when the receiver tunes to signals from at least three satellites), so you’ll know where to look for satellites in the sky. The satellites continuously transmit its orbital location and exact time. The time between sending and receiving satellite signal from the GPS receiver, it becomes distance by a simple arithmetic formula (time is measured in nanoseconds). By picking up signals from at least three satellites, the GPS receiver by triangulation determines its position on the surface of the earth by the value of the longitude and latitude (two dimensions). Such coordinates can come in degrees, minutes or seconds or measurement units used in other geodetic systems. The recruitment of four satellites WHO also facilitates the height of the receiver with respect to sea level (three dimensions). The position coordinates and other information which may facilitate the receptor, are updated every second or every dI seconds. QUALITY OF SIGNALS ISSUED The quality of the signals emitted by satellites, called SQ is a function of their position in the sky, in relation to the status of the receiver antenna, or satellite operational status. The quality of the signals affects the accuracy of the information provided by receivers. Some models have graphic scales for indicating the quality of the received signals. TYPES OF GPS RECEIVERS There are two types of GPS receivers, the fixed and portable. The fixed are larger, operate battery-powered cars, planes or ships and have separate external antennas. Usually they interconnected with other electronic instruments such as radars, sensors, plotters, autopilots, etc.. The ms talkies are much smaller and can also feed on the energy of any vehicle (with adapter) may work by batteries. The antennas are usually installed inside the receiver (most have external antennas are available as optional purchase), although there are also removable to be installed outdoors. Some portable models can also be interconnected with other electronic instruments. FREQUENCY MILITARY AND CIVILIAN. As mentioned in previous bulletins, each satellite transmits data series in two different codes. One of the codes, the code P is reserved for military use, the other code, called SPS, is destined for civilian use. Each code has a different transmission frequency. CODE Q: The exact code, known by the acronym protected PPS and also called P-code is reserved strictly for military use and as its name suggests offers the highest accuracy and precision. Is emitted in the frequency of 1227.6 MHz. SPS CODE: The code of ordinary acquisition, also called SPS C / A code is intended for civilian use. All GPS receivers “civilians” are tuned to this code. Is emitted in the frequency of 1575.42 MHz. Selective Availability The GPS system’s central station, located in the United States, degrades the accuracy of civil signals (through a small difference in the time of transmission / reception) so that gives a small error, error estimate between 25 and 100 meters . This signal degradation is known as selective availability (SA). This difference in the position coordinates all important for the use of GPS for civilian running applications, is due to security reasons, do not forget that some missile guidance systems using GPS guidance. DIFFERENTIAL GPS It is called differential GPS (DGPS) the modified system, developed by civil receiver manufacturers, is trying to achieve or approach the precision offered by the military code. To achieve this increased precision is necessary to attach the GPS receiver through a special interface connection, another type of receptor. This additional receiver (must be compatible) captures signals from a network of radio beacons located in coastal stations. A device that has the DGPS function, interconnected to a suitable recipient can “outwit” selective availability imposed by the U.S. Defense Department, to have another set of complementary data, thus providing a precise coordinates position of between five and ten meters. Each brand of GPS for parameters facilitates compatibility between DGPS receivers and receivers feature that capture the signals from the beacons. The use of the DGPS system is applicable only in marine navigation and is particularly useful in docking maneuvers with low visibility. LIMITATIONS OF GPS. The GPS is without doubt the most simple and accurate navigation system currently available, however it should not be the only vehicle navigation as well be damaged, the U.S. Department of Defense can and it has done on occasion disrupt, modify or degrade the signals when it deems appropriate. The signals emitted by satellites behave in a way as light as they can penetrate the glass and plastic, but do not pass through mountains, tunnels, buildings, metal surfaces or similar structures. The antenna receivers should be oriented so that it “visual access” to the satellites. In navigation mode, a GPS receiver indicates the distance remaining to reach destination in a straight line. Keep in mind that the land is virtually impossible, even in the desert, following a straight path for long periods because the terrain accidents force frequently change the direction. FUNCTIONS OF A GPS RECEIVER. The main function of a GPS is to report on the position occupied by through the longitude and latitude, so that position can be located easily on a map or plan. But there are other functions for easy navigation: NAME AND DESCRIPTION OF SERVICE POSITION: GPS position display. Facilitates the almost exact location receptor. This has to be the GPS signals captured by at least three satellites. HEIGHT: 4 WHO to capture the GPS satellites indicates the height above the sea. (sensitive to Selective Availability) TIME: GPS once initialized, but not receive satellite signals indicating the time and date, if it receives signals indicating the exact time. TRANSIT POINT OR POINT OF REFERENCE: The waypoint’s position is one place on the earth’s surface expressed by its coordinates. A waypoint can be a starting point, destination or an intermediate crossing point on a route.