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Spectrum analyzer in the EMC rectification and reform of the application is how, many novices are not very clear, in order to help you solve this problem, the following editor will explain in detail for you, people with this need can come to learn, I hope you can gain something.

A preface

Spectrum analyzer is the most widely used tool in electromagnetic interference (EMI) testing, diagnosis and troubleshooting. A spectrum analyzer is as important to an electromagnetic compatibility (EMC) engineer as a logic analyzer in the hands of a digital circuit designer. Because of its wide frequency range, bandwidth selectivity and wide range scanning CRT display, the spectrum analyzer can be used in almost every EMC test application.

The following picture shows common spectrum analyzers:

Introduction to the Test function of two-Spectrum Spectrometer

In the EMC rectification, the spectrum analyzer can observe the spectrum of the signal, the power of the signal, the spurious, harmonic and Intermodulation distortion of the test system.

1. Measure the frequency and power of the signal

The following picture shows the display of the spectrometer after the signal source sends out a single carrier signal. Through MARK--PEAK, the operation can see that the signal frequency is 74.35MHz and the power is 3.64dBm.

2. Intermodulation distortion test

The following picture shows the test chart of signal Intermodulation distortion. The power difference between signal and Intermodulation signal (dB) can be tested by mark-DELT marking function.

3. Harmonic test

The spectrometer can test the harmonics of the measured signal, it can use the spectrum test function of the spectrometer, MEASURE-harmonic test, or it can pass the frequency f of the test signal, and then change the center frequency of the spectrometer to 2f ~ 3f. . Then PEAK to test the power of each harmonic.

5. PAPR test

In the spectrum analyzer test, another function is the peak-to-average ratio test (CCDF). The peak-to-average ratio test of a modulated signal is shown below.

Three application cases

1. The following picture shows the control board of a display screen, which is rectified because the clock radiation exceeds the standard.

2. the clock signal diagram before rectification, the radiation source is found by the spectrum analyzer, and the clock signal is rectified.

3. According to the clock signal comparison chart after rectification, after adding the spread spectrum IC test board, the peak energy decreases obviously, and the decrease is up to 22dB.

4. Clock signal comparison diagram of full frequency band.

The spectrum analyzer can be used for development, diagnosis and quantitative analysis. the main advantage is that the analyzer can easily correct the measured data according to the pre-quantitative analysis results in the EMC test, so that the frequency domain results can be visualized, so that the design and rectification engineers can better understand what faults are occurring and where they are occurring.

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