EXFO IQS-12002B Calibration System - Manual (Page 69)

Calibration Methods
Calibration System 65
Power Meter
8. At the end, the global nonlinearity is the sum of all the local
nonlinearities expressed in decibels (dB), starting calculations from
the reference power level where the nonlinearity is zero (higher order
terms are negligible).
The equations to use are as follows:
For n < 0
For n = 0
For n > 0
where:
n < 0 indicates power levels lower than the reference power.
n > 0 indicates power levels higher than the reference power.
NL
i
is the local nonlinearity for the step (i = 0 for the step where P
ab
is
the reference power).
The result is a list of global nonlinearities for the whole power range in
steps of 3,01 dB.
The largest nonlinearity relative to the reference power is:
This procedure can be performed with decreasing and/or increasing the
power sent to the DUT.
∑
+
=
− =
1
0
i n global
) (
n
i
NL P NL
0 ) (
0 global
= P NL
∑
=
+ =
n
i
NL P NL
1
i n global
) (
NL
max
max NLglobal ( ) dB ( ) ± =