Military of China, force comment.
Military of China, force comment.

quasi-zenith satellite positioning, “Wizard number” diagram.
Japan’s “Wizard number” navigation satellite diagram

our reporter Chen Chao

9 11, Japan launched the first self-developed positioning satellites. At 20:17 on the 11th, Japan’s Tanegashima Space Center using the H-2A rocket launched its first quasi-zenith satellite positioning, “Wizard number” 28 minutes 27 seconds after the satellite successfully separated from the rocket, solar panels normal to start power generation 6.7 kW, in line with the design value of 6.4 kW. The launch of the “Wizard number” is the first quasi-zenith satellite system, the test run if there are no technical problems, Japan will be launched by the other two quasi-zenith satellite positioning.

seeking to develop autonomous navigation system

Japan, a U.S. ally, and the U.S. GPS (Global Positioning System) in turn the world including Japan, free, then why should Japan develop its own satellite positioning system? Japanese government recently disclosed information, the Japanese prime minister and minister responsible for science and technology policy-led “integrated development and utilization of space science and technology conference dedicated investigation of the” 2004 data said, in view of the U.S. GPS satellite navigation system has become infiltrated into Japanese people living in the heart of the system location-based applications, in order to prevent occurrence of unexpected events, Japan should establish either with GPS, and a gradual transition to be independent-measuring satellite navigation system.

as a secondary and enhanced GPS systems, quasi-zenith satellite navigation system is expected to improve GPS positioning in Japan and around the performance of building quasi-zenith satellite navigation system satellite navigation program in Japan in the first step.

Although Japan is now the quasi-zenith system must also rely on GPS to complete the user location, but according to plan, it was entirely possible to upgrade an independent satellite navigation system.

set of “auxiliary” and “enhance” a

“Technology Daily,” the reporter Ocean University of Tokyo, Japan, a GPS expert, Shanghai Galileo limited company’s technical adviser Fan Chunming learned that quasi-zenith satellite navigation system consists of three synchronized with the Earth’s tilted orbit satellites. It can also transmit the GPS navigation signal, which allows users to treat it as a GPS satellite to use. Meanwhile, the satellite system adds an enhanced signal that Japan provide a higher quality of location-based services, also increased the use of a test signal.

Fan Chunming to reporters details of the quasi-zenith satellite features. He said, first of all, each star of the system over in Japan, working 8 hours, 3 stars alternating rotation, thus ensuring any time have a quasi-zenith satellite in Japan, “Zenith” on duty, which makes the forest of the building valleys of the city center and the user can not be blocked by the satellite Fengyun to “enhance” GPS in harsh environments positioning capabilities.

Second, in addition to a now all the civilian GPS signal, the system also increases the GPS program in the L1C signal, which is Japan’s first satellite to provide L1C signal services. Because these signals are identical with the GPS, the existing GPS receiver almost no changes.

again, the signal can be enhanced by increasing the rate of the navigation data, navigation data in an increase in the compensation information fields such as the ionosphere to improve positioning accuracy, GPS is expected to be the original 10-meter positioning accuracy to 1 meter. The signal is not compatible with the GPS signal, you need special receivers.

addition, the Japanese in order to develop future research satellite positioning technology, but also a special test signal, the measured bit code used is the Japanese name of KASAMI code, navigation message bit rates up to 2k. But from the entire system architecture point of view, and then move the system to increase several satellites can be extended into an independent regional navigation system. From the principle of speaking, by the quasi-zenith satellite together with the rest, six or more satellites to build a practical three-dimensional space area satellite positioning system.

set up their own experimental platform upgrade

sum up, the quasi-zenith satellite navigation system in addition to set “supplement and enhance the” GPS performance in a, but also satellite navigation technology to provide a test and demonstration platform in orbit, will greatly promote the Japanese developments in the field of satellite navigation.

such as enhanced signal to the user positioning accuracy up to 1 meter, the satellite’s own precise orbit must meet higher requirements. In principle, the quasi-zenith as a regional service system, as long as there is enough in the service area of ??ground stations, not necessarily like the GPS ground stations are also available as the global distribution of high line of sight between the user and satellite measurements distance accuracy, thus ensuring the user’s positioning accuracy. However, in real-time service in what can not be successful reference to the U.S. has accumulated decades of experience to achieve the current level is still unknown, quasi-zenith satellite just to provide a real test platform.

Japan-measuring Chang Tian Mingsheng will learn to navigate, “Technology Daily” correspondent, said that although the satellite is not in China, “head” to enhance the signal in the ionosphere compensation information is not directed against China, but as auxiliary function of the GPS-compatible signals, or to provide services to Chinese users. In particular, the satellite is now the only one with four civilian satellite signals, these signals with a good position to improve the performance of Chinese users is useful. (Technology News)