| 摘要 |
A method of compensating for non-linearities in an end amplifier (F) having a given transfer function HR, H phi for amplitude and phase respectively and included in a radio transmitter of quadrature type for linear, digital modulation, and in which table look-up units (ST, CT) store the digital sine and cosine values (I(t, alpha ), Q(t, alpha )) of the quadrature components determined by a given signal vector alpha . According to the method the values of the transfer functions HR, H phi for the quadrature modulated radio signals r(t, alpha ) are calculated by addressing memory units (MH1, MH2) which store a number of values of HR and H phi . The sine and cosine values of the addressed values of HR and H phi are also formed. The thus calculated values are multiplied by the stored digital values in the table look-up units (ST, CT) and by the inverted value of HR. As a result, new modified values i(t, alpha ), q(t, alpha ) are obtained for the quadrature components, which compensates for the non-linearities in the final amplifier. <IMAGE> |
