Transmission tests on a trial system of telephone service for aircraft

This paper gives results of transmission tests on the air-to-ground telephone system which is presently in operation at 450 mc on a trial basis with land base stations located at Chicago and near Detroit. Received carrier level measurements, using a chart recorder, were made at both land stations prior to the start of commercial service on September 15, 1957. The effects of base station antenna height, aircraft elevation and distance from base station, nulling, capture in the overlap zone and aircraft antenna patterns are discussed.