Operation
The tropospheric scatter system operated around 900 MHz, and utilized both space diversity and frequency diversity, multiplexing a maximum of 132 simultaneous voice channels. The tropospheric hops used pairs of 60 ft (18 m) or 120 ft (37 m) parabolic, billboard like reflectors pointed at a low angle into the horizon. The radio waves were scattered by the tropopause, returning to Earth beyond the horizon, allowing communication between stations hundreds of kilometers apart. Having two antennas allowed for space diversity, meaning that if tropospheric conditions degrade on one path the second path might still be clear and communications would not be disrupted. For frequency diversity, each antenna transmitted two separate frequencies. Using both frequency and space diversity was called quad diversity. System power output for most shots was 10 kW and used 60 ft (18 m) antennas. Longer shots used 120 ft (37 m) antennas with 50 kW and shorter shots used 1 kW and 30 ft (9 m), round parabolic dishes.
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