R&S ESU Series - 7 Measurement of the Third Order Intercept (TOI)

Operating Manual 1302.6163.12 - 03 4.211
R&S ESU Instrument Functions
Analyzer Mode
Measurement example
The AM modulation depth of a carrier modulated with 1 kHz is to be measured at
100 MHz.
Remote command: CALC:MARK:FUNC:MDEP ON;
CALC:MARK:FUNC:MDEP:RES?
4.8.13.7 Measurement of the Third Order Intercept (TOI)
If several signals are applied to a transmission two port device with nonlinear char-
acteristic, intermodulation products appear at its output by the sums and differences
of the signals. The nonlinear characteristic produces harmonics of the useful signals
which intermodulate at the characteristic. The intermodulation products of lower
order have a special effect since their level is largest and they are near the useful
signals. The intermodulation product of third order causes the highest interference.
It is the intermodulation product generated from one of the useful signals and the
2nd harmonic of the second useful signal in case of two-tone modulation.
The frequencies of the intermodulation products are above and below the useful sig-
nals. Fig. 4.14 Intermodulation products PU1 and PU2 shows intermodulation prod-
ucts P
I1
and P
I2
generated by the two useful signals P
U1
and P
U2
.
[PRESET] The R&S ESU is set to the default setting.
[CENTER: 100 MHz] The center frequency is set to 100 MHz.
[SPAN: 5 kHz] The span is set to 5 kHz.
[AMPT: 0 dBm] The reference level is set to 0 dBm.
[MKR FCTN] MARKER 1 is switched on and positioned at the maximum
of the displayed trace.
[MODULATION DEPTH:
1 kHz]
The measurement of the AM modulation depth is switched
on. MARKERS 2 and 3 (delta markers) are set to the adja-
cent peak values of the trace and are activated for the fre-
quency entry.
The AM modulation depth is output in % in the marker info
field.
When 1 kHz is entered, MARKER 2 can be exactly posi-
tioned on 1 kHz and MARKER 3 at -1 kHz from the refer-
ence marker.