FIELD: radio engineering. SUBSTANCE: level detector detects level 215 of input signal 205. Rectifier 210 receives input signal and generates rectified signal 215. Preselector 220 detects rectified signal and attenuates high-frequency components at frequencies close of multiple frequency of decimation sample. Signal 225 filtered in advance is decimated and filtered by low-pass filter 240 whose bandwidth is below input frequency of input signal 205. Level detector can be used to control circuit of variable amplification stage that amplifies input signal on basis of level forming device compressing or expanding dynamic range. EFFECT: complete integration in microcircuit, reduced repeated noises in spectrum. 8 cl, 10 dwg
