Receiver basic sensitivity switching circuit - uses for switching directional voltages derived from receiver discriminators

摘要

The basic sensitivity of receivers is switched over by a device which reduces the gain of the receiver during tuning. The direction voltages (UR1) which can be derived from the discriminator (2) of the receiver on either side of the zero crossing of its discrimination curve, are used as switching voltages inducing a first switching state of a bistable switching stage (4). A further directional voltage, derived from the intermediate frequency and related to its mean frequency, is field strength dependent and forms a switching voltage (U2) for inducing a second switching state of the bistable switching stage. During its first state the switching stage supplies to the receiver amplifier stage (3) a switching signal (S) which reduces the receiver gain.