CMU RF User Correction
1100.4903.12 1.31 E-10
Level points
Level of the measured or generated signal in dBm, to be arranged in
descending order, starting in row 2 (highest level). The level points must be
positive or negative integer numbers, followed by a colon, and can be
distributed across the entire RF input and output power range of the
connectors (see data sheet). Negative levels must be preceded by a minus
sign “-“; using a plus sign “+” for positive numbers is not allowed.
Correction values
n times m level correction values for the measured or generated signal in dB (if
n is the number of frequency points, which is equal to the number of correction
values per table row, and m is the number of level points). The total number of
correction values n times m must not exceed 120 (it is possible though to
choose m=120 and n=1 and vice versa).
The level correction values must be in the range between -1.20 dB and +1.20
dB. This is sufficient to compensate for a frequency response or level response
caused by the test setup. Larger, correction factors can be defined by
combining the user correction with a constant external input or output
attenuation (see section RF Connectors in Chapter 4). Two consecutive
correction values may be separated by any number of spaces or tabs.
Positive (negative) correction values for an output signal compensate for an
external attenuation (gain) and increase (decrease) the generator level.
Positive (negative) correction values for an input signal are added to
(subtracted from) the measured RF signal levels.
Interpolation Rules
The CMU uses the values in the correction tables to interpolate correction factors at arbitrary frequency
and level values. The following rules apply:
• At constant frequency, the correction value associated to the level point P
m
is valid in the level
range between (P
m+1
+ P
m
)/2 and (P
m–1
+ P
m
)/2: The ranges with constant value adjoin each other
in the middle between two consecutive level points.
• At constant level, the correction factors are linearly interpolated between consecutive frequency
points.
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