Increasing the noise immunity of radio receiving paths with automatic sensitivity control

The relevance of the study of automatic sensitivity control systems (ASC) is determined by their demand for the creation and modernization of radio receiving paths (RRP) with increased noise immunity for radar systems, radio navigation and radio communication. The article analyzes typical attenuating ASCs, which are traditionally widely used to match the dynamic range (DR) of the RRP with the DR of a group radio signal, determined by the current state of the electromagnetic environment at the receiving system location. The fundamental possibility of increasing the noise immunity of RRPs with attenuating ASCs is shown on the basis of the current analysis of the resulting output signal in the IF main filter band. At the same time, it was found that the procedure for determining the optimal value of the attenuator transmission coefficient is characterized by low response speed. In addition, an increase in noise immunity in a RRP with such ASC leads to a significant loss of sensitivity. To overcome the disadvantages of attenuating ASCs, structures that implement the exchange of the transmission coefficient of the RRP to DR and linearity are proposed. Studies of various possible ASC structures have shown that with a proportional exchange of the transmission coefficient for the DR, an improvement in the noise immunity of the RRP is provided while maintaining a high sensitivity of the system. An original ASC system is proposed, which is invariant to the sampling step of the transmission coefficients of controlled elements with increased performance. The considered structural solutions and algorithms make it possible to optimize the technical appearance of RRPs for radar, radio navigation and radio communication with increased noise immunity and to adapt their characteristics to the conditions of nonstationary electromagnetic environment.