R&S SGT100A User Manual page 225

®
R&S SGT100A
2
3
4
With the provided settings, you can define a polynomial function with up to 10
order to describe the predistortion function.
The graphical display updates on-the-fly and visualize of the resulting AM/AM and
AM/PM functions.
5. Select "Polynomial Order = 4" (n = 4).
6. Set the polynomial coefficients a
7. Select "Apply".
The instrument loads the configured values, calculates the correction values, and
displays the predistortion functions.
Figure 7-24: Predistortion Settings > Polynomial: Understanding the displayed information
1a
2a
1b, 2b
white dashed line
AM/AM yellow curve = AM/AM correction values, calculated as ΔAM/AM(x) = AM/AM(x) - x
AM/PM yellow curve = AM/PM correction values, calculated as ΔAM/PM(x) = AM/PM(x)
3a, 3b
4
5
8. To store the defined predistortion function:
a) Select "Save/Recall Polynomial"
b) Navigate throughout the file system and enter a "File Name", e.g. MyPolyno-
User Manual 1176.8674.02 ─ 07
= Resulting AM/AM predistortion function, calculated as AM/AM(x) = abs[P
= Ideal AM/PM function (constant phase at 0 degrees)
= Resulting AM/PM predistortion function, calculated as AM/PM(x) = tan
Re[P (x)]}
DPD
= Normalized value of the current RF RMS power level
= Normalized value of the current PEP of the generated RF signal
= Correction values
= Ideal zero function; no correction is necessary
= X-axis scale, calculated form the
= Negative correction coefficients
= Values greater than the
mial_4thOrder
Signal Generator Settings
Applying Digital Predistortion
to b .
0 4
Input Range (PEP
PEPin Max are ignored
(x)]
DPD
-1
{Im[P (x)]/
DPD
th
)
in
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