A discussion on orbital analysis - Radar tracking at R.R.E., Malvern

Abstract

The decision to initiate radio and radar satellite tracking work at the Royal Radar Establishment was taken at the end of 1960, and followed directly from our experience in working with Echo 1 satellite. During the week following its launch, positional information on Echo 1 was transmitted to N.A.S.A. Goddard Space Flight Center by teletype. The equipment used was a 10 cm radar feeding a 45 ft. paraboloid dish aerial, which was steered by slaving to an optical sight; it was a system adapted in a hurry from its main work programme of Moon-echo investigations, and very limited in its capability for extended satellite tracking work. In order to participate in communications tests via Echo 1, another aerial was recovered from disuse and pressed into service at short notice. This was a 20 ft. wood-and-wirenetting device. A primitive system of semi-automatic steering control was designed and built, a receiver on 960 Mc/s headed by a parametric amplifier was supplied by the Post Office Engineering Department, and, after 10 days’ intensive work, signals were received at Malvern via Echo 1 from Bell Telephone Laboratories, Holmdel, New Jersey. Although the signal level was below the frequency-modulation threshold, so that intelligible speech could not be received, the signal strength was measured to be within half a decibel of its theoretically predicted value for the air-and-space transmission path. This successful initial experiment, performed jointly by the Post Office and R.R.E., was a landmark in the progress of U.K. work in the space/ground environment, and led by separate paths to Goonhilly Downs and the present R.R.E. Satellite Tracker. The influence of the 1960 experiment, and in particular the prediction-aided pointing control method used, can be discerned at both installations today.