I. Yu. Golikov, A. V. Levsha, V. V. Pechurin, V. A. Shashlov

Wide use of a radio-frequency spectrum in high frequency range for communication and increase in different interference sources sophisticate signal and interference environment in a receiving point. Individual signals and interferences forming a group radio signal are the causes of nonlinear distortions in the receiving channel. 3rd order intermodulation components make high influence on an interference immunity of the signal receiving. It is caused insignificant frequency mismatch of the interfering signal concerning desired signal frequency. It is shown that one of the ways to reduce nonlinear distortions is using of adaptive receiving systems, which adapt to signal and interference environment in real time mode. Tunable rejection filter and controlled attenuator at the input of adaptive receiving sys-tems were offered. Tunable rejection filter is used for reduction of nonlinear distortions at the operation frequencies. It allows enhancing noise-to-signal ratio due to minimization of band-width total noise level. It has been offered to use controlled attenuator before an amplifier for signal and noise level measurement and gain optimization. Optimization gain method has been proposed. The adaptive receiving system dummy has been developed for confirmation of experi-mental results. It has been shown that benefit may achieve 5-10 dB.