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Suggested Citation:"Spot Beams." National Research Council. 1995. The Global Positioning System: A Shared National Asset. Washington, DC: The National Academies Press. doi: 10.17226/4920.
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Page 132

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TECHNICAL ENHANCEMENTS FOR FUTURE CONSIDERATION 132 Table 4-2 GPS Wide-Band Signal Augmentation Performance with a 10-Kilowatt Jammer System Scenario Code Status Carrier Telemetry Status Jammer distance at Jammer distance Jammer distance at Range error at loss loss of lock (meters) for 1-meter range loss of lock (meters) of lock (meters) error (meters) 1. Y-code unaided —— —— —— —— standard antenna 2. Y-code aided standard —— —— —— —— antenna 3. Y-code aided nulling —— 20,000 —— —— antenna 4. Wide-band unaided —— 60,000 —— —— standard antenna 5. Wide-band aided —— 31,000 —— —— standard antenna 6. Wide-band aided —— 1,800 —— —— miniature antenna 7. Wide-band aided null/ —— 450 —— —— beamforming antenna Spot Beams The advantages of introducing a new, 200-MHz wide-band signal at a higher carrier frequency for coping with a jamming environment were discussed above. While this offers the best technical solution, the difficulty of finding a suitable frequency band and the need to develop a new suite of military receivers to acquire the signal must be considered. An alternative solution to a wide-band signal for improved anti-jam margin would be the use of spot beams. By employing a steerable spot beam on the satellite to illuminate an area of

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The Global Positioning System (GPS) is a satellite-based navigation system that was originally designed for the U.S. military. However, the number of civilian GPS users now exceeds the military users, and many commercial markets have emerged. This book identifies technical improvements that would enhance military, civilian, and commercial use of the GPS. Several technical improvements are recommended that could be made to enhance the overall system performance.

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