When this new system first demonstrated that high accuracy is achievable. With further reduction of equipment costs and both the modernization an d augmentation of GPS, numerous additional applications will develop. This includes terrestrial, marine, and aviation applications. The future uses of GPS are limited only by one’s imagination. Many of  the present uses we’re described in various articles written as early as 1982.

Some examples for applications on land are vehicle navigation and information systems including Intelligent Vehicle/Highway Systems (IVHS) and Intelligent Transportation Systems (ITS ). Another land application which has been mentioned is t he use of GPS to automate various types of machinery. For example, it should be possible to automate the grading and paving equipment used for road building. Equipment could be run around the clock without operator with GPS performing all motion operations based upon a digital terrain model stored in the  computer of the equipment . There will also be numerous applications in survey and geodesy as well as precise time determination and – one of the fastest growing GPS applications  time transfer. Available resources of telephone companies, power companies, and many others are enhanced by precis e timing. Other future GPS applications concernatmsphere sounding . The data will contribute to a better understanding of the structure of the atmosphere leading for example to improved models for weather analysis.

Marine applications will include vessel navigation and information systems , precise harbor entrance system s, and oceanography in general. DGPS will mostly be used for these purposes , and dense networks of monitor stations are to be established along the coasts . One example is the network of real-time DGPS beacon sites along the U.S. coasts operated by the USCG.

For aviation, GPS will be integrated into other navigation systems like INS to fulfill the high reliability and integrity requirements. Applications will include enroute navigation and surveillance, approach and landing, collision avoidance, and proximity warning. Aircraft could be operated in an automated mode with takeoffs and landings being performed by integrating GPS and computer units .

The  use of GPS will  increasingly  be extended  to space for  precise  positioning  of (e .g. , earth  remote sensing)  satellites, for attitude determination of spacecraft , and for  missile  navigation.

GPS  modernization

In January 1999, the U.S.A. announced a $400 million initiative to modernize GPS. Key feature of the initiative is the implementation of new signal structures in future satellites.

Future GPS satellites

The first Block IIR  satellites are already in orbit, while the Block IIF or follow on satellites are under construction. They will be launched from 2007 onwards. The Block III satellites carrying GPS into 2030 and beyond are presently being designed.

The next generation of satellites will have many improvements over the present satellites. It is planned to include the capability to transmit data between satellites to make the system more independent. The Autonomous Navigation (Auto-Nav) capability will allow the satellites to essentially position themselves without extensive ground tracking . In summary, the future satellites will have the following advantages:

• Navigation accuracy is maintained for six months without ground sup-port. No survivable control and no user modifications are required.

• Uplink jamming concerns are minimized.

• One upload per spacecraft per month instead of one or even more per day is performed.

• Need for overseas stations to support navigation uploads is reduced.

• Improved navigation accuracy is achieved.

These features mainly benefit the military use of the system, since civilians will still be required to provide their own ephemerides for accurate surveys .

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