Operating Manual 1302.6163.12 - 03 4.213
R&S ESU Instrument Functions
Analyzer Mode
The intercept point is the fictitious level where the two lines intersect. It cannot be
measured directly since the useful level is previously limited by the maximum two
port output power.
It can be calculated from the known line slopes and the measured spacing a
D3
at a
given level according to the following formula.
(39)
The 3
rd
order intercept point (TOI), for example, is calculated for an intermodulation
of 60 dB and an input level PU of -20 dBm according to the following formula:
(40)
TOI
The TOI softkey enables the measurement of the 3
rd
order intercept point.
A two-tone signal with equal carrier levels is expected at the R&S ESU input.
MARKER 1 and MARKER 2 (both normal markers) are set to the maximum of the
two signals. MARKER 3 and MARKER 4 (both delta markers) are placed on the
intermodulation products. When the function is enabled, the frequency entry is acti-
vated for the delta markers. They can be set manually.
The R&S ESU calculates the third order intercept from the level spacing between
normal markers and delta markers and outputs it in the marker info field.
Remote command: CALC:MARK:FUNC:TOI ON;
CALC:MARK:FUNC:TOI:RES?
Example
A two-tone signal with frequencies of 100 MHz and 101 MHz is applied to the RF
input of the R&S ESU. The level of the two signals is -10 dBm.
SELECT
MARKER
The SELECT MARKER softkey activates the selection of a marker for functions
MODULATION DEPTH and TOI. Thus, the markers can be fine-adjusted for these
functions.
The markers are numerically selected in a data entry field. Delta marker 1 is
selected by entering '0'.
If the marker is in the switch-off state, it will be switched on and can thus be shifted.
Remote command: CALC:MARK1 ON;
CALC:MARK1:X <value>;
CALC:MARK1:Y?
IP3
a
D3
2
--------
P
N
+=
IP3
60
2
------
–20dBm–()10dBm–+
[PRESET] The R&S ESU is set to the default setting.
[CENTER: 100.5 MHz] The center frequency is set to 100.5 MHz.
[SPAN: 3 MHz] The span is set to 3 MHz.
[AMPT: -10 dBm] The reference level is set to -10 dBm.
[MKR FCTN] MARKER 1 is switched on and set to the signal peak.
[TOI] The R&S ESU sets the 4 markers to the useful signals and
the intermodulation products and calculates the third order
intercept. The result is output in the marker info field.
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