Nonlinearity compensation system for transmission element - uses pre-distortion mixer with two diodes at input for intermediate frequency

摘要

The method is intended for radio link systems, and the compensation is carried out by a predistortion mixer with an oscillator input. There is an h.f. output and a further input for the i.f. signal carrying the useful signal, to which the two diodes of opposite polarities are connected. The nominal h.f. level at one diode is higher than at the other, and interference level is applied to the diodes inversely proportional to the nominal h.f. level. Level and phase of the oscillator signal are adjustable at the other diode. The h.f. nominal level at the diode with smaller nonlinearity is greater than at the other diode with greater nonlinearity. Increase of the nonlinearity is achieved by reduction of the oscillator power. After difference formation a negative interference element appears. Its phase and magnitude is adjusted by adjustment of the oscillator level phase and magnitude at one of the diodes.