Transoceanic communication by means of satellites
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The existence of artificial earth satellites and of very low-noise maser amlifiers makes microwave links using spherical satellites as passive reflectors seem an interesting alternative to cable or tropospheric scatter for broad-band transatlantic communication. A satellite in a polar orbit at a height of 3000 miles would be mutually visible from Newfoudland and the Hebrides for 22.0 per cent of the time and would be over 7.25° above the horizon at each point for 17.7 per cent of the time. Out of 24 such satellites some would be mutually visible over 7.25° above the horizon 99 per cent of the time. With 100-foot diameter spheres, 150-foot diameter antennas, and a noise temperature of 20°K, 85 kw at 2000 mc or 9.5 kw at 6000 mc, could provide a 5-mc base band with a 40-db signal-to-noise ratio. The same system of satellites could be used to provide further communication at other frequecies or over other paths.
[1] Eberhardt Rechtin,et al. Design and performance of phase-lock circuits capable of near-optimum performance over a wide range of input signal and noise levels , 1955, IRE Trans. Inf. Theory.
[2] J. R. Pierce,et al. Orbital Radio Relays , 1955 .
[3] J. G. Chaffee. The Application of Negative Feedback to Frequency-Modulation Systems , 1939 .
[4] John R. Carson. Frequency-modulation: Theory of the feedback receiving circuit , 1939 .