Ceyear 4051 Series, User Manual

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4. Operating Instruction
4.2 Advanced operation guide
158
Fig. 4.77 Results of Harmonic Distortion Measurements
4.2.16 Three-order intermodulation (TOI)
4.2.16.1 Basic concept
Three-order intermodulation, also known as TOI for short, is a means for analysis and measurement of
intermodulation product of communication system equipment. Mutual interference between equipment is very
common in communication systems, which is usually caused by distortion products from equipment such as
amplifiers and frequency mixer. TOI can measure, calculate and display output intercept points (IP3) and
signs on the curve show measured signals and three-order products.
After selecting [TOL], press 【 Meas Setup 】 key to enter the parameter settings menu of third-order
intermodulation measurement, press
【
Meas Control
】
key for remeasuring, continuous switch and single
sweep.
4.2.16.2 Measurement Example
This section mainly describes how to measure third-order intermodulation for signals (use a signal generator
to simulate an intermodulation signal).
Step 1. Connect the RF output ports of two signal sources with a directional coupler, and place the
device under test (e.g. an amplifier) in between the output port of the directional coupler and input port
of the analyzer, as shown in Fig.4.78.
Step 2. Set signal source as below:

Set the frequency on one signal source at 500 MHz.

Set the frequency on the other signal source at 510 MHz to make a frequency space of 10 MHz between
the two signal sources.

Set the power of the two signal sources to achieve same measured amplitude of spectrum analyzer. The
power is set at -2.0dBm in this example.