The new GPS navigation and positioning technologies progress

【GPS News U.S. Global Positioning System (GPS) navigation satellites are gradually modernized. GPS navigation aids from the U.S. Air Force began, and gradually developed into an important dual-use technology. The exact GPS location and timing information, has become a worldwide variety of military and civilian, scientific research and commercial activities is an important resource

GPS satellite signals in the development and improvement of GPS navigation satellites launched since 1978 has been the first of its type Ⅰ, Ⅱ Ⅱ A and Ⅱ R batch to batch development. Section Ⅰ, Ⅱ and Ⅱ A total of 40 batches of the satellite is manufactured by Rockwell, and 20 satellite Ⅱ R batch manufactured by Lockheed Martin. In 1996, Boeing acquired Rockwell's aerospace and defense business, is currently manufacturing 33 more advanced batch Ⅱ F satellite. United States is also considering the development of a new generation of GPS using spot-beam satellites (GPS-Ⅲ).

GPS since 1994, a comprehensive work to improve the work has been in progress. This is because the requirements of civil users of GPS jamming and interference with a better performance, higher security and integrity; the military requires a larger satellite launch with the civil power and the new military signal source separation; and on the use of GPS navigation "smart" weapons, speed up signal acquisition is even more important.

Accuracy of civilian GPS Navigation biggest improvement so far in May 2, 2000, the United States stopped the intentional reduction of civil signal performance (known as selective availability, the S / A) practice. In the S / A work, civilian users in 99% of the time only 100 meters accuracy. However, when S / A cut off, navigation accuracy increase, 95% of the location data can fall to 6.3 m radius circle.

GPS satellites transmit two codes: coarse acquisition code (C / A code) and precision code (P code). The former is a civilian, the latter only