Coordinates

Determine the location of data collection

To a point on the celestial sphere determine the location of the celestial sphere on the establishment of the spherical coordinate system. There are two basic elements:

① basic plane. By the celestial sphere on a selected set by the great circle. Known as the great circle of laps, the two-lap as a spherical geometry is one of the very coordinates.

② the main point, also known as the origin. Selected by the celestial sphere on a pole of the coordinates of the great circle and the circle of the intersection identified.

Tian Tian at this point in the coordinates of the location of the two spherical coordinates calibration:

① coordinates or the first to coordinate. Made the point and the coordinates of the great circle of the pole, said Deputy laps from the main point to the vice-circle and circle the arc length of the intersection to coordinate.

② second latitudinal coordinates, or coordinates. From the circle-on effect along the circle to the point of the great arc for the latitudinal coordinates long. Any point on the celestial sphere can be the location from which to identify only two coordinates. This spherical coordinate system is orthogonal coordinates. For different circles and the main base, and to coordinate the different measurements used by the way, leads to a different celestial sphere coordinates, a commonly used amlodipine coordinates, the equatorial coordinate system, the ecliptic coordinates and coordinates Silver Road

GPS prospects

As GPS technology with the all-weather, high-precision measurement and automatic features, as an advanced means of measuring productivity and new, have been integrated into the national economic construction, national defense construction and social development of various applications.

With the end of the Cold War and the global economy booming, the U.S. government announced the 2000-2006 period, in ensuring national security is not threatened the United States, under the premise of the policy cancellation SA, GPS civilian signal precision on a global scale to improve and use of C / A code of conduct point positioning accuracy from 100 meters to 20 meters, which will further promote the application of GPS technology, increasing productivity, operational efficiency, scientific level and quality of life and stimulate the growth of GPS market. According to experts predict that in the United States, alone automotive GPS navigation system, in 2000 after the market will reach 3 billion U.S. dollars, while in China, car navigation market will reach 5 billion yuan. This shows that, GPS technology market prospect is very impressive.

GPS Frequencies

L1 (1575.42 MHz): Mix of Navigation Message, coarse-acquisition (C/A) code and encrypted precision P(Y) code, plus the new L1C on future Block III satellites.

L2 (1227.60 MHz): P(Y) code, plus the new L2C code on the Block IIR-M and newer satellites.

L3 (1381.05 MHz): Used by the Nuclear Detonation (NUDET) Detection System Payload (NDS) to signal detection of nuclear detonations and other high-energy infrared events. Used to enforce nuclear test ban treaties.

L4 (1379.913 MHz): Being studied for additional ionospheric correction.

L5 (1176.45 MHz): Proposed for use as a civilian safety-of-life (SoL) signal (see GPS modernization). This frequency falls into an internationally protected range for aeronautical navigation, promising little or no interference under all circumstances. The first Block IIF satellite that would provide this signal is set to be launched in 2009.

GPS History

The basic idea to build up a navigation system using satellites already existed before World War II. In May 11, 1939 the German aerospace scientist Karl Hans Janke announced in Berlin a patent for a "Position indicator concerning to aircrafts“ which had been issued on November 11, 1943.In the patent, he assumed two distant bodies (satellites) which are permanently sending electromagnetic signals. Those signals can be received and be shown on a screen as a vector. By laying a map on that screen it would be even possible to determine origin and direction of an object.

The design of GPS is based partly on similar ground-based radio navigation systems, such as LORAN and the Decca Navigator developed in the early 1940s, and used during World War II. Additional inspiration for the GPS came when the Soviet Union launched the first Sputnik in 1957. A team of U.S. scientists led by Dr. Richard B. Kershner were monitoring Sputnik's radio transmissions. They discovered that, because of the Doppler effect, the frequency of the signal being transmitted by Sputnik was higher as the satellite approached, and lower as it continued away from them. They realized that since they knew their exact location on the globe, they could pinpoint where the satellite was along its orbit by measuring the Doppler distortion.

The first satellite navigation system, Transit, used by the United States Navy, was first successfully tested in 1960. Using a constellation of five satellites, it could provide a navigational fix approximately once per hour. In 1967, the U.S. Navy developed the Timation satellite which proved the ability to place accurate clocks in space, a technology the GPS relies upon. In the 1970s, the ground-based Omega Navigation System, based on signal phase comparison, became the first world-wide radio navigation system.

The first experimental Block-I GPS satellite was launched in February 1978.[4] The GPS satellites were initially manufactured by Rockwell International (now part of Boeing) and are now manufactured by Lockheed Martin (IIR/IIR-M) and Boeing (IIF).