The Global Positioning System: A Shared National Asset (1995)
Chapter: Spot Beams
Table 4-2 GPS Wide-Band Signal Augmentation Performance with a 10-Kilowatt Jammer
|
System Scenario |
Code Status |
Carrier Telemetry Status |
||
|
|
Jammer distance at loss of lock (meters) |
Jammer distance for 1-meter range error (meters) |
Jammer distance at loss of lock (meters) |
Range error at loss of lock (meters) |
|
1. Y-code unaided standard antenna |
—— |
—— |
—— |
—— |
|
2. Y-code aided standard antenna |
—— |
—— |
—— |
—— |
|
3. Y-code aided nulling antenna |
—— |
20,000 |
—— |
—— |
|
4. Wide-band unaided standard antenna |
—— |
60,000 |
—— |
—— |
|
5. Wide-band aided standard antenna |
—— |
31,000 |
—— |
—— |
|
6. Wide-band aided miniature antenna |
—— |
1,800 |
—— |
—— |
|
7. Wide-band aided null/beamforming antenna |
—— |
450 |
—— |
—— |
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
