Rohde & Schwarz SMIQ02B - Loading New Distortion Characteristics

SMIQ Noise Generator and Distortion Simulator
1125.5555.03 2.387 E-9
2.24.2 Loading New Distortion Characteristics
The SMIQ is supplied with a preset distortion characteristic that corresponds to the typical characteristic
of a traveling wave tube amplifier in WorldSpace satellites. The name of the characteristic set as
standard is TWTA (Traveling Wave Tube Amplifier). Other user-defined distortion characteristics can
also be stored in the SMIQ. If several characteristics are stored, they can be selected under SELECT
CHARACTERISTIC... .
A new characteristic is formed by the interpolation points of AM/AM and AM/PM conversion. Entry is
possible via IEC/IEEE bus. The SMIQ determines the complete characteristic based on these
interpolation points by cubic spline interpolation. The factory-set characteristics (TWTA) of AM/AM and
AM/PM conversion are shown in the following figures. The continuous line indicates the interpolated
characteristic. The circles show the reference points. The input values are on the x-axis, the output
values on the y-axis.
Fig. 2-241 AM/AM conversion
Fig. 2-242 AM/PM conversion
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Output values
Input values
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
50
45
40
35
30
25
20
15
10
5
0
Output values (degree)
Input values