By Denis J Curtin
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Four to two for this series of spacecraft. Electrothermal hydrazine propulsion (with a specific impulse of 300 sec) is employed to provide north-south stationkeeping. The total spacecraft mass budget is summarized in Table 1. Communications Subsystem The expanding requirements of the INTELSAT system have led to satellites with higher communications capacity. Wider bandwidth is the most effective method to obtain the larger capacity. On INTELSAT V, four frequency bands are employed: 14- and 6-GHz bands are received by the spacecraft and 11- and 4-GHz bands are transmitted.
The 6-GHz receiver begins with a 4-stage bipolar amplifier at 6-GHz, followed by a low-loss balanced mixer. The 14-GHz receiver employs a single-stage 14-GHz tunnel diode amplifier (TDA), followed by a low-loss balanced mixer. In both cases, the mixer is followed by a transistor amplifier. The number of stages in the transistor amplifier differs for each of the global, hemi, zone, and spot varieties of receivers. All 6-GHz receivers contain an interstage commandable attenuation that can provide either nominal or extra high gain.
A high number (around 80%) of these INTELSAT events studied can be correlated with times of magnetospheric substorm activity. This supports the theory that the anomalies are induced by interaction of the spacecraft with energetic electrons which are injected into the local morning time quadrant during periods of magnetospheric substorm activity (Rosen, 1976). e. different parts of the spacecraft charge at different rates, leading to intrasatellite potential differences of sufficient magnetude to cause arcing.