GB549465A - Improvements in carrier-signal receivers - Google Patents

Abstract

549,465. Valve circuits for wireless reception. HAZELTINE CORPORATION. June 28, 1941, No. 8171. Convention date, July 10, 1940. [Class 40 (v)] A receiver of the homodyne type comprises a main signal channel tuned to a desired carrier wave, an auxiliary channel in which the carrier alone is obtained and fed back into the main channel to provide a desired carrier having an amplitude in excess of neighbouring undesired carriers. In Fig. 1, a tuned input circuit 11, 12 feeds the main channel comprising a tunable R.F. amplifier 10, tunable coupling circuit 16, 17, broad band R.F. amplifier 15, detector 18 and output 19, 20, Part of the energy from circuit 11, 12 is applied to an auxiliary channel comprising an untuned broad-band R.F. amplifier 21 and limiter 34 of the kind described in Specification 552,499, the output of which is fed through a tuned link circuit 27, 28 back to the input circuit 11, 12. Limiter 34 brings the desired carrier and neighbouring carriers down to a common level so that after passing tuned circuit 27, 28 the desired carrier is predominant and thus when fed into the main channel produces a desired carrier of larger amplitude than the neighbouring carriers. In a modification, Fig. 3 (not shown), the link circuit is coupled with the' main channel after the first R.F. stage so as to reduce the possibility of oscillation. In a further modification, Fig. 4 (not shown), the output from .the limiter is amplified -and fed back into the detector stage of the main signal channel. A voltage is also fed to the detector to render it unresponsive to carrier signals of amplitude less than the reinforced desired carrier.