UHF Receiver with decreased distortion due to multipath reception

摘要

In a UHF receiver in which volume control is carried out as a function of received field strength, distortion due to multipath reception is prevented by use of a band-pass filter connected to the output terminal of the IF section which furnishes a signal indicative of received field strength. The low frequency noise signals appearing at this terminal in the presence of multipath reception are passed by the band-pass filter and subsequently rectified to create a DC control signal which closes a switch. This in turn increases the time constant of the connecting circuit between the field strength output terminal and the control input of the volume control circuit. The increase in time constant suppresses the above-mentioned low frequency oscillations which occur only during multipath reception, so that the output of the volume control circuit is not affected by such multipath reception.