Operating Manual Vol 1 - ES Documentation

SMIQNoise Generator and Distortion Simulator2.24.2 Loading New Distortion CharacteristicsThe SMIQ is supplied with a preset distortion characteristic that corresponds to the typical characteristicof a traveling wave tube amplifier in WorldSpace satellites. The name of the characteristic set asstandard is TWTA (Traveling Wave Tube Amplifier). Other user-defined distortion characteristics canalso be stored in the SMIQ. If several characteristics are stored, they can be selected under SELECTCHARACTERISTIC... .A new characteristic is formed by the interpolation points of AM/AM and AM/PM conversion. Entry ispossible via IEC/IEEE bus. The SMIQ determines the complete characteristic based on theseinterpolation points by cubic spline interpolation. The factory-set characteristics (TWTA) of AM/AM andAM/PM conversion are shown in the following figures. The continuous line indicates the interpolatedcharacteristic. The circles show the reference points. The input values are on the x-axis, the outputvalues on the y-axis.10.90.8Output values0.70.60.50.40.30.20.100 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Fig. 2-241AM/AM conversionInput values0Output values (degree)51015202530354045500 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Input valuesFig. 2-242AM/PM conversion1125.5555.03 2.387 E-9