Future of GPS
New Applications
• • • • • • Intelligent Vehicle/Highway Systems (IVHS) Intelligent Transportation Systems Automated Construction Equipment Time Determination/Time Transfer Atmospheric Sensing Aircraft Navigation and Landing
GPS Modernization
• New Block IIF scheduled to be launched in next few years (2007?)
– Ability to transmit data between satellites – Autonomous navigation
• • • • • Navigation accuracy maintained for six months (????) Uplink jamming less of a concern One upload per spacecraft per month (??) Minimize ground tracking Improved navigation
Augmented Signal Structure
• SA is now off and likely to stay off • Additional L5 carrier frequency
– Ability to correct for ionospheric effects when using carrier phase – Modulated by a new civil code (similar to P-code) – L2-L5 produces extra wide lane – L1-L5 can be used as ionosphere free
• Military Y-code replaced by split M-code
GPS Augmentation
• Want to use GPS for aviation
– Reliability needs to be extremely good – Want to augment GPS to provide additional reliability and improve results
• Local Area Augmentation Systems (LAAS) will use pseudolites
– Should allow precision approach and landing
• Category II/III
GPS Augmentation
• Can also use geostationary satellites
– Will have broadcast capability – Transmit DGPS corrections and integrity messages
• Wide Area Augmentation System (WAAS) will use Inmarsats to augment GPS
– Operational sometime
GNSS
• Global Navigation Satellite System (GNSS) • Integration of different satellite navigation systems
– Already have capability of combining information from GPS and GLONASS – Also includes augmentation from other kinds of satellites (like Inmarsat) – Also include Galileo when launched
GNSS/LORAN-C
• Long Range Radio Navigation (LORAN)
– Used mostly for maritime navigation – Broadcast stations organized into ‘chains’ – Very similar to GPS
• cannot provide vertical component
– Can be used to augment GPS
Hardware
• In short, hardware will continue to get better, cheaper, smaller
– Cost will drop if quantities increase in a way that everyone has (at least) one GPS receiver working in his/her life – Resolution of wave will improve (<0.1%) – More channels (for increased number of observables)
• More frequencies and more satellites
Software
• In short, software will continue to get more sophisticated and run faster
– Improved modeling or solution for unknown parameters – Better algorithms for solution – Faster computers will allow more to be done in the same amount of time
GPS Products
• Data will continue to improve
– Centimeter level orbits will be available – Centimeter level positioning will be possible in real time – Sub-centimeter positioning will be possible by post-processing