Communications at megamile ranges

Abstract

Megamile communications call for the fullest use of advanced modern technology. This paper surveys the design of a deep-space communication system. The basic constraints and capabilities of a low-noise ground receiving system are covered in detail, including antenna temperature contributions from galactic noise, tropospheric and ionospheric attenuation, and earth radiation through antenna side lobes. Low-noise preamplifiers, large high-gain antennas, and narrow-band phase-lock receivers are also considered. Digital biphase modulation, used in Pioneer V, is compared with more sophisticated bi-orthogonal coding systems. Both types of coding systems are compared with error rate as a parameter, with the ideal error-free Shannon limit. The design of Pioneer V and its record of achievement are described. Included are explanations of the coherent transponder within the spacecraft, and of the command transmitter and telemetry reception equipment at the ground stations.

Multitone signalling system employing quenched resonators for use on noisy radio-teleprinter circuits

“…There are two basic methods of comparing different systems in noisy circuits. 9 The first is the absolute comparison in terms of the ratio W = signal energy per bit noise power per unit bandwidth for a given error rate. Thus, if the measured signal/noise power ratio is S/N, C = signalling speed in bits/sec and B = bandwidth in which noise is measured,…”