The Global Positioning System: A Shared National Asset (1995)

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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