Linearization of limiters in systems «filter – limiter – filter»

Abstract

There are many sets of linear and nonlinear devices in any radio engineering systems contains, they perform such operations with signals as generating electrical oscillations of various shapes, modulation, detection, frequency conversion and performing some other operations on signals, including logical operations that non-operational without which. When the signal and interference interact in nonlinear devices, signal jamming occurs, which is one of the main factors limiting the noise immunity of radio engineering information transmission systems, including radio control lines. The executive device of any types of the radio control lines contains a limiter. An executive device of any types of the radio control lines contains the limiter required. In this case, there is a sufficiently strong suppression of the signal by interference, which leads to a noticeable decrease in the potential and real noise immunity of the control radio line with binary coding during piecemeal processing of binary combination signals in the limiter, which is a classical nonlinear device. Losses in noise immunity can be compensated by switching to processing binary signals as a whole, while the limiter is transferred to the input of the circuit, where it acts as part of the filter – limiter–filter (FLF) system. The paper shows that the limiter operating in the FLF system with bandpass filters behaves like a linear device with all the consequences that follow from this. It is established that at low signal-to-noise ratios in the band of the first filter F1 at the equality takes place, where is the signal-to-noise ratio at the output of the FLF system, which can be interpreted as the linearization of the limiter operating in the FLF system. The results obtained make it possible to use in radio control lines whole processing instead of piecemeal processing of binary signals using a limiter in the FLF system operating in the input circuits of the radio receiver, thereby obtaining a noticeable gain in noise immunity due to the linearization of the limiter works in FLF system.