Scholars said the Japanese Quasi-Zenith Satellite navigation systems can be upgraded as an independent
Data Figure: Japan has launched “guide” was quasi-zenith satellite
9 11, Japan’s Tanegashima Space Center in the use of H-2A rocket launched its first “quasi-zenith” positioning satellite “lead the way number “, which is Japan’s first launch of its self-developed navigation and positioning satellites. As planned, the “guide number” after the trial run without technical problems, Japan will be launched by the other two “quasi-zenith” positioning satellites.
Japan’s “quasi-zenith” satellite program a long time. In June 2000, the Japanese Space Development Committee submitted a report entitled “Improving Japan’s space development system, expand the use of new areas of aerospace,” the report, decided to implement spatial data infrastructure (I-SPACE) program. “Quasi-Zenith” satellite system is the “I-SPACE” plans to focus on the development of the three systems. The aim is to develop the next generation of autonomous navigation systems in Japan, and test high-speed mobile communications satellite.
“quasi-zenith” is a system combines satellite navigation, mobile communications and broadcasting satellite system features, designed to run in Japan over the U.S. GPS satellites to provide “enhanced auxiliary” function, improve navigation positioning signal reception quality and accuracy. The current plan is the accuracy of civil signals from ten meters to enhance the level of an order of magnitude, the control of one meter or less, and this accuracy has been very close to the U.S. military GPS signal accuracy of.
“quasi-zenith” satellite system will bring Japan’s four major benefits
we all know, the U.S. global satellite navigation system (GPS) has retention’s sake, GPS civil signal has been as good as military signals, although under normal circumstances, with the GPS navigation map can still be used normally, but in some extreme conditions, there will still be positioned offset phenomenon. Japan’s “quasi-zenith” navigation satellite, just want to “patch” approach, by increasing the density of the satellite over Japan, to resolve the accuracy of civilian GPS navigation signal problems. The benefits are clear:
first, the new system will help achieve a more precise global positioning. “Quasi-Zenith” functions can be divided into the GPS satellite positioning to complement and strengthen the two cases. The so-called “complementary” is simply to increase the number of GPS satellites, the GPS provides the same free service. The “enhanced” part is by modifying the information to improve the accuracy of GPS, so accuracy is higher than ordinary GPS can provide location-based services paid features.
Second, because the “quasi-zenith” satellites and geostationary satellites in different orbits, so even with the same frequency band that does not interfere with each other, can improve the utilization of the frequency band.
Third, in Japan, is now widely used in communications satellites in geosynchronous orbit and ground elevation of not more than 48 degrees, the signals due to ground-level building block, only cover the actual city area of ??30%, while the “quasi-zenith” satellite elevation angle of 60 degrees or more, coverage of up to 100%. In addition, the existing satellite system used in digital wireless communication technology and image processing level is low, the new system will compensate for this defect.
fourth, with “quasi-zenith” satellite synchronous orbit satellites can be observed to unobserved in the polar regions for scientific research to provide more valuable information.
seek R & D capabilities, enhance navigation safety
Japan, a U.S. ally, and America’s GPS also assured the world including Japan Free open. So, why should Japan develop its own satellite positioning system?
one very important reason is that Japan believes that the U.S. GPS has penetrated into every aspect of national life in Japan, which is obviously very unsafe. In order to prevent the occurrence of unexpected events, the Japanese believe to be compatible with the GPS and the establishment of a gradual transition to be independent-measuring satellite navigation system. Currently, Japan’s “quasi-zenith” system must also rely on GPS to complete the user location, but according to plan, the future is entirely possible to upgrade an independent satellite navigation system.
worldwide, GPS in addition to widely used in the military field, the development of the field in the civilian is in full swing. To vehicle navigation technology, for example, in the United States, Japan and European countries has been widely used Japanese vehicle navigation technology is a world leader, which is Japan’s national geographic characteristics and historical development are inextricably linked. Compared with the United States and Europe, Japan, the small land area, population density, while a longer history of the city, the modern city are mostly based on the ancient city developed, dense urban road network, the layout is not reasonable, but the transformation of the expenses high, resulting in the traffic complex. Since 1992, Japan began a large-scale application of GPS navigation system, maintained at the current annual sales of several million units, and more than 80 percent of new car factory had installed vehicle navigation systems.
as the U.S. global positioning system in the world on a wide range of applications, GPS has become an important worldwide source of information, related products and services market has been expanding rapidly, has become an important industry. Meanwhile, satellite navigation and positioning technology with important military value for a country’s national defense and military security is important. Japan’s space technology has advanced decision not willing to be left behind, both do not want to lose the market, but also do not want to completely dependent on the defense capacity of others, and so develop their own independent satellite navigation system has become a government target, the development of with a regional navigation and positioning capabilities of the “quasi-zenith” satellite system has become inevitable.
Japan will not meet in the “quasi-zenith” attached to the GPS system to do a role
comprehensive national strength as a symbol of global satellite navigation system has increasingly become a major national business cards – the current U.S. GPS and Russian GLONASS system has been built and applications, is building the system, including China’s Compass system, the European Galileo system. Now, with “guide number” of the launch, the addition of a new face in this area – Japan’s “quasi-zenith” system. Well, it’s competitive strength make?
the moment, “quasi-zenith” limitations of the system is obvious, it’s just a regional positioning system. Even in 2015 a plan of all three satellite launch mission, but also mainly to meet the increase in Japan and around the GPS positioning function. At this stage, it is only as a supplement and enhance the GPS system in 2015 did not have a real, independent global competitiveness. But this is only the Japanese plan to build the satellite navigation system in the first step. In the long run, with the number of satellites within the system and the density increases, the technically entirely possible to upgrade an independent satellite navigation system, satellite navigation to provide a complete auxiliary functions, and this time probably in 2020 ~ 2025 between years.
2008 年 11 月 11 ~ 14, by Japan Institute of Navigation, Global Navigation Satellite System Research, Japan Aerospace Studies and the Ocean University of Tokyo co-hosted the “2008 GPS/GNSS (Global Satellite navigation system) International Conference “held in Tokyo. From more than 30 countries, 400 delegates attended the conference, published more than 200 excellent articles. Japanese Chief Cabinet Secretary Takeo Kawamura said at the meeting special lecture, the satellite positioning system as the country’s infrastructure, has been the Japanese government’s attention. If Japan is now developing in the “quasi-zenith” satellite navigation system, an additional number of satellites from three to six, plus a Japanese geostationary satellite will be able to form autonomous regional satellite navigation system. Therefore, “Quasi-Zenith” system is a step by step, gradually rolling, growing system, Japan will not be satisfied merely “quasi-zenith” attached to the GPS as a “second rate” role, it will go from behind the scenes on the stage. (Li Li Author: National Defense University)