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Monitoring and measuring L-band signals from GPS satellites for the USAF |
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Communicating with and commanding the low earth-orbiting OPAL and PICOSAT spacecraft system (UHF) in connection with a DARPA / Aerospace / Stanford small satellite program |
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Measuring intergalactic hydrogen clouds at L-band in a Stanford University experiment |
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Detecting telltale UHF signals from Mars-bound spacecraft with Stanford and JPL |
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Monitoring of the Mars Global Surveyor UHF communication system shortly after launch using 10 kW transmissions |
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Configured as a UHF inverse synthetic aperture radar |
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| Antenna type | Parabolic reflector |
| Site | Stanford University Radio Science field site, academic reserve area |
| Horizon | Maximum 3° |
| Diameter | 150 ft (45.7 m) |
| f/d ratio | 0.42 (focus is 63 ft from surface at center) |
| Surface mesh | 5/8-in spacing, soft aluminum hex pattern |
| Surface roughness | Approximately 1-in |
| Gravitational deformation | Approximately 1-in at edge for minimum to maximum elevation |
| Beamwidth/gain attainable (with appropriate feeds) | L-band (1420 MHz): 0.25° beamwidth, 35% efficiency, 52 dB
UHF (400 MHz): 1.0° beamwidth, 55% efficiency, 43 dB VHF (150 MHz): 3.0° beamwidth, 55% efficiency, 35 dB |
| Feed arrangement | Prime focus, tripod structure, feed house, tilting feed platform for small apparatus, high power cables |
| Reflector structure | Steel torus ring, aluminum tubular rings and radial trusses, non-homologous, light-weight design |
| Weight | Reflector structure: 100,000 lb
Total structure: 300,000 lb |
| Motion | Elevation over azimuth, wheel and track, CR-170 rail, steel 4-wheel alidade on 140-ft dia. track for azimuth, rack (bull gear) and pinion spur gears for elevation motion |
| Practical limits | Azimuth: 2-turns, azimuth cable wrap via central hole and tunnel
Elevation: 3 to 87° |
| Programmed tracking speed | 1°/s, useful for LEO satellite tracking to elevations of approximately 65° |
| Programmed tracking acceleration | 1°/s2 |
| Motion control | AC vector controlled 25 hp motors giving full torque through entire speed range + to – including 0 with dynamic braking (60 hp capacity) |
| Control computer | PC with appropriate multiple parallel interfaces, programmed in Pascal, code similar to Sondrestromfjord (Greenland) incoherent scatter radar, GPS timing available |
| Positional resolution | 0.01° azimuth and elevation, 1-turn binary optical encoders, unique azimuth encoder offset mechanical connection |
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| PICOSAT OPAL |