220269 ⎘
Gain control in amplifiers or frequency changers without distortion of the input signal; Automatic control in amplifiers having semiconductor devices; Muting amplifier when no signal is present or when only weak signals are present, or caused by the presence of noise signals, e.g. squelch systems; Muting during a short period of time when noise pulses are detected, i.e. blanking dependent on the rate of noise pulses