GPS latitude and longitude should be understood

Want to know the latitude and longitude in GPS, you must first understand the GPS, know the source of latitude and longitude: 1.GPS System Composition

GPS is the abbreviation of the Gloabal Positioning system, meaning global positioning systems, mainly from the ground control station, the sky flying satellite, we hold the receiver of three large chunks, we use the GPS, including hand-held and vehicle-mounted navigation machine is essentially GPS receiver. 2.GPS receiver

Receiver large and small, diverse, there are pocket-type, backpack, car, ship, airborne and so on. The commonly used handset receives the L1 signal, but also has the dual frequency receiver, makes the precise localization use. 3. Coordinate system

topographic map coordinate system:

The topographic map of our country uses Gauss-gram Lugeping plane rectangular coordinate system. In this coordinate system, the horizontal axis: the equator, expressed in Y, the longitudinal axis: the Central Warp, which is represented by X, the coordinate origin: the intersection point of the central warp and the equator, expressed in O. South of the equator is negative, the North is positive, the central warp East is positive, the West is negative. China is located in the Northern hemisphere, so the ordinate is positive, but in order to avoid the central Longitude line west of the situation, the coordinate longitudinal axis of 500 kilometers west.

Beijing 54 coordinate system:

1954 China in Beijing set up a geodetic coordinate origin, the use of Krasovsky ellipsoid, according to this calculation of the various geodetic control point coordinates, known as the Beijing 54 coordinate system.

GS84 coordinate system:

Is the world's universal latitude and longitude coordinate system.

6-degree belt, 3-degree belt, central warp

China adopts 6-degree and 3-degree bands: 1:25,000 and 1:50,000 of the topographic map using 6-degree projection, that is, 6 degrees, from the zero meridian start, from west to east each by the difference of 6 degrees for a projection belt, the global total of 60 bands, with 1-60 ... Said. 1:10,000 of the topographic map using a 3-degree zoning, starting from longitude 1.5 degrees, every 3 degrees for the area, with 1-120 said, the world divided into 120 projection belt. 4. The source of latitude and longitude

In order to accurately show the locations around the earth, people have assumed a coordinate system for the Earth's surface, which is the latitude and longitude line. So, how did the initial longitude and latitude line arise. And how to measure it. In 344, Alexander Crossing Hainan invaded, and then East Levy, the Army geographers Niercos along the way to search data, ready to paint a "world map." He found the route along the east of Alexandria, from west to east, regardless of the seasonal change and the length of sunshine are very similar. An important contribution was made-the first time a parallel was drawn on Earth, from the Gibraltar, Str. Of, along the Taurus and Himalaya to the Pacific Ocean.

Alexander's empire was short-lived and soon disintegrated. But in the Egyptian city named Alexander, there appeared a famous library, the Eratosthenes of many years as curator, proficient in mathematics, astronomy, geography. He calculated that the circumference of the earth was 46 250-kilometer, drawing a map of the world with 7 meridians and 6 parallels. 5. The expression of latitude and longitude

The 1884 International Longitude Conference stipulates that through the Meridian Instrument Center of the London Green Wedge Observatory, the warp is 0° warp. From 0° longitude east longitude, west, east and west, 180 °. It is customary to divide the Earth into two hemispheres with 20 ° longitude and 160 ° longitude. If you cut the Earth from the center of the Axis into the north and south, half of it is called the Northern Hemisphere, and the lower half is called the southern hemisphere. The plane that is cut is called the equatorial plane. The equatorial surface intersects the Earth's surface called the equator. The parallels are getting shorter from the equator to the poles, narrowing to a point at the poles. The scientists set the equator at 0°, which is divided into 90 degrees from the equator to the Poles, south of the equator, and north of the equator. In the computer or GPS on the latitude and longitude of the regular use of degrees, points, seconds and degrees, degrees, minutes, seconds. The mixed way of the second, the degree, minute, second of the system is 60, degrees, degrees, minutes, seconds. The second system is 100, the conversion must pay attention to. It is possible to approximate that the distance between each latitude is constant 111KM, 1.85KM per minute, 31.8M between each second. The distance between the longitude gradually decreases with latitude, and can be calculated by the formula:

The longitude 1° length =111.413cosφ a 0.094cos3φ kilometer (latitude φ).

In general, the data obtained from GPS is latitude and longitude, and there are many ways to express it by DDD.DDDDD: the decimal fraction (5 digits) of degrees. For example: 31.12035°ddd.mm.mmm, Degree. Fractional decimal fraction (3 digits). such as 31°10.335 ' ddd.mm.ss, degrees. minute. For example 31°12 ' 4 "

Any fixed point on the earth can be expressed with a definite latitude and longitude.