4-GPS的现代化.ppt

测绘学院测绘学院 School of Geodesy and School of Geodesy and Geomatics Geomatics GPS GPS 的现代化与最新进展的现代化与最新进展魏二虎魏二虎 ******@. ******@. 武汉大学武汉大学测绘学院测绘学院 卫星 Signal Structure Decision Tree Signal Structure Decision Tree L2 L2 New Military Frequency New Military Frequency L1/L2 Reuse L1/L2 Reuse New Civil Frequency New Civil Frequency Somewhere Else Somewhere Else L2 L2 is Lm L2 is Lm Lc Lc Lm ““ Do Do Nothing Nothing ”” Signals on IIR, IIR-M, & IIF Signals on IIR, IIR-M, & IIF L5 Civil L5 Civil L2 M L2 M L2 P/Y L2 P/Y L2 Civil L2 Civil L1 M L1 M L1 P/Y L1 P/Y L1 C/A L1 C/A IIF IIF IIR-M IIR-M IIR IIR Signal\SV Signal\SV A New Military Frequency (Lm) A New Military Frequency (Lm) ?? Feb Feb ‘‘ 97: JPO began study of new frequency for 97: JPO began study of new frequency for military use military use ?? The Military Problem The Military Problem –– PDD directed prevention program PDD directed prevention program –– Wartime GPS use reduced to Wartime GPS use reduced to direct Y-code on L direct Y-code on L 2 2 –– Inevitable C/A-code on L Inevitable C/A-code on L 2 2 must be denied (per PDD must be denied (per PDD guidance) guidance) –– Postulated signal plan - no options for NAVWAR Postulated signal plan - no options for NAVWAR ?? Military seeking alternative frequency to allow Military seeking alternative frequency to allow –– Prevention of hostile C/A use without signal Prevention of hostile C/A use without signal fratricide fratricide –– Protection of military use (higher power signal) Protection of military use (higher power signal) without adverse impact on civil use (outside of AOR) without adverse impact on civil use (outside of AOR) L L M M Signal/Platform Concept Signal/Platform Concept anization L M ON BLOCK IIF L M SATELLITES MODIFY EXISTING PAYLOAD ADD L M SUBSYSTEM DEDICATED VEHICLE NON-GPS HOST NAV SOLUTION AUGMEN- TATION Reuse L 1 L 2 L-BAND SIGNAL SIGNAL IN NEW BAND S-BND (SGLS) < L 2 (JTIDS) X-BAND L 3L 5