The measurement result of Debug Mode is not processed.

The Debug Mode is the default mode, and the measurement results are not processed, and the Pretest Mode is the mode after adding the Correction Factor of the PR-01 AC Probe.

The characteristics of the PR-01 are listed below. Users can also find the relevant specifications in the GKT-008 user manual.

When users use the function of EMC Pretest > AC Voltage Probe, the Pre-amplifier preset is turned off. PR-01 is mainly used to measure the EMI signal of the AC power supply.  A large signal feedback during the low frequency measurement is likely to occur that will damage the RF end of the GSP-9330. Therefore, when using the function of the AC Voltage Probe, the preamplifier is preset off. Users can still turn on the amplifier according to the requirements of the measurement.

The highest DC bias of PR-01 should not exceed 50Vdc. It is recommended to test after the power supply of the DUT is connected and stabilized.

Different products will use different regulations for EMC testing according to their electrical characteristics. According to the existing regulations, in the conducted test, 9 kHz is suitable for the conducted test of lighting equipment, and 150 kHz is suitable for the conducted test of general audio-visual equipment, household appliances and information products.

The following table is a list of regulations and conducted EMC test frequency ranges for products in various commonly used categories.

A 10dB attenuator is designed in the GLN-5040A to protect the spectrum analyzer during testing. In the GSP-9330, the compensation function is also designed. 10dB compensation can be obtained by turning on (EMC Pretest >> EMC ON >> EMI Test >> Band selects the conduction band >> More 1/2 >> GLN-5040A 10dB Comp. ON / OFF >> Select ON to get the real value.

GLN-5040A supports DC input and supports up to 50Vdc input. However, since GLN-5040A is designed primarily for AC LISN, it can be used for reference when using DC input, however, it is not the same as DC LISN.

NO. The regulations have clear definitions for the setup and environment of the test equipment, including the height of the test table, the size of the grounding surface, the distance between the DUT and the test equipment, the power outlet, etc. The DUT in the regulation is placed on the test table and LISN is placed on the ground surface.

If the test site is not built in accordance with the regulations in the general working environment, the measurement results may cause errors.

When the laboratory is constructed, it usually uses a power filter (with filtering, voltage regulation, etc.) and is built with a standard field that meets the regulations. Therefore, there is less power supply noise after the LISN. GIT-5060 is mainly used to isolate the ground leakage current after LISN and the DUT is connected, and there is no filtering and voltage regulation function, so there will be some differences.

Refer to "What do you do when there is a test result difference between the pre-compliance and certified lab?" and "How to remove the effects of environmental noise when performing Pre-compliance measurement?"

If the test capacity is greater than GIT-5060 requirement, two methods are recommended: first, replace GIT-5060 with AC Source, but it is better to use the Linear Mode and it has passed the CE specification. Second, use EMI power filter. This method requires special EMI manufacturers to construct because site evaluation and further specification evaluation are required to meet your needs.

Yes. But not to choose Switching Mode AC Source to avoid the mixing of PWM signals and try to choose CE certified.  The noise of AC Source will be smaller.

GPL-5010 operates from 9 kHz to 200 MHz with an attenuation of 10 dB to 12 dB. Detailed specifications can be found in GPL-5010 user manual, which can be downloaded from the website.

If users concern big signal fluctuation while conducting EMI testing, especially the spectrum analyzer might be damaged when using PR-01 to directly contact AC circuit, use GPL-5010 to protect GSP-9330, as shown in the following diagram.

Common mode and differential mode noise can theoretically be analyzed in conducted and radiated EMI. However, when it comes to the actual noise suppression technology, it is more meaningful to discuss the conducted noise. It is also possible to seek reference countermeasures through measurement. The following figure shows the common circuit for conducted EMI suppression in power supply. CY, LCM is a common mode noise filtering network, and CX is a differential mode noise filtering network.

If we can measure the common mode component and the differential mode component of the conducted noise separately, we know that we should adjust the common mode filter CY, LCM, or the differential mode filter CX to reduce the noise. The following is a brief description.

and in the figure represent the currents on the two power lines. In theory, we can treat and as the sum of the common mode and differential mode noise currents, namely:

and , is common mode current, is differential mode current.

Furthermore, we found that and can be obtained from

Comparing the two equations, as long as the signal of one of the power supplies can be added to the other power line signal in the forward and reverse directions, the sum and the difference of and can be obtained separately, and the and can be measured. Therefore, a and coupler/adder can be designed at the power supply terminal of the DUT to obtain and .

There is an approximation, which uses a current probe with a spectrum analyzer to measure the sum of the two power lines, as shown in the following figures.

In Figure (a), run two power cables through a current probe, connect the probe with a spectrum analyzer to obtain . Run one of the power cables around the probe (b) to make the current direction opposite to the direction as shown in. (a). By so doing, the can be measured from the spectrum analyzer, and the results are shown below. It can be seen that the common mode noise component is higher than that of the differential mode, and we know that the common mode filter and need to be adjusted to reduce the common mode noise component. Although this is not an accurate measurement, it is an approximation that is worthy of reference.

Common mode and differential mode noise

1. A power supply cable with a magnetic ring can suppress conducted or radiated EMI by the characteristics of the magnetic ring.
2. The better the isolation, the better the power supply wire can suppress the EMI from radiating out of the power supply to form radiated EMI, but the cost is relatively higher.