FIGURE 76. - NOISE TEMPERATURE PROFILE Noise from the SSPS. — Diagrammatically the SSPS can be considered as a three-part system consisting of (a) a generator with output power P, (b) a transmitting antenna with gain G. and (c) a filtering system placed between the antenna and the generator.* a. The Generator The generator consists of a large number of Amplitrons (8 x 10s). each feeding about I m2 of the transmitting antenna surface. The noise emanating from this 1 m2 is coherent, since it originates in the same Amplitron. However, it is incoherent with the noise from other Amplitrons. The total power delivered to the antenna at the design frequency (3300 MHz) is essentially 6.4 x 109 watts (+98 dBw). The present value of the noise power is 55 dB below this level, or +43 dBw. This value is inherent in the tube design and is for a 1-MHz band, and will be included in Case (a) calculations. Case (a) is represented as presently achievable technology, and in the future it is expected that the Amplitrons can be designed so that the peak value of the noise power will be at 85 dB below the fundamental, so that the level of the noise power will be at +13 dBw. This future expectation will be included in Case (b) calculations.
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