Abstract
EMI and EMC testing are critical processes in ensuring that electronic devices operate reliably without causing interference to other equipment. The LISUN EMI-9KB EMI Test Receiver plays a crucial role in detecting and resolving electromagnetic interference issues by fundamentally addressing self-interference. This article explores the working principles of EMI and EMC testing systems, particularly focusing on the EMI-9KB. We will delve into how these systems mitigate self-interference, supported by experimental data, and highlight their significance in maintaining compliance with international standards.
Introduction
Electromagnetic Interference (EMI) and Electromagnetic Compatibility (EMC) are key factors that determine the reliability and functionality of electronic devices. EMI refers to the unwanted electromagnetic emissions that can disrupt the operation of other electronic equipment, while EMC ensures that a device can function properly in its electromagnetic environment without causing or falling victim to such interference. EMI and EMC testing are essential to meet regulatory standards and avoid issues related to signal integrity, system failures, or safety hazards.
The LISUN EMI-9KB EMI Test Receiver is a comprehensive system designed to detect and analyze EMI in electronic devices. It plays a pivotal role in identifying interference sources and ensuring devices meet EMC standards. However, EMI test systems themselves can be vulnerable to self-interference, which can compromise the accuracy of the testing process. This article will examine how the EMI-9KB system addresses self-interference, ensuring reliable and precise measurements.
EMI and EMC Testing: Principles and Challenges
EMI and EMC testing involve measuring the electromagnetic emissions of a device and assessing its susceptibility to external interference. These tests are conducted to ensure compliance with standards set by regulatory bodies such as the Federal Communications Commission (FCC), International Electrotechnical Commission (IEC), and the European Union’s CE Marking requirements.
EMI Test Receiver EMI-9KB
Key Testing Parameters in EMI and EMC Testing
• Conducted Emissions: Measures the electromagnetic energy conducted through cables and wires connected to the device under test (DUT). Conducted emissions testing identifies interference that travels along power lines or signal cables.
• Radiated Emissions: Measures the electromagnetic energy radiated directly from the DUT into the environment. Radiated emissions testing is crucial for identifying unwanted signals that can affect other devices in the vicinity.
• Immunity Testing: Assesses the DUT’s ability to operate correctly when exposed to electromagnetic disturbances, such as voltage spikes, electrostatic discharge (ESD), or radio frequency interference (RFI).
• Harmonic and Flicker Testing: Evaluates how the DUT impacts the quality of the power supply, including harmonic distortion and voltage fluctuations.
Challenges in EMI and EMC Testing
• Self-Interference: The test equipment itself can emit electromagnetic noise, affecting the accuracy of the measurements. Self-interference is a significant challenge that requires careful management.
• Environmental Noise: External electromagnetic sources, such as mobile phones, Wi-Fi routers, and industrial equipment, can introduce noise into the testing environment, leading to false results.
• Measurement Sensitivity: High sensitivity is required to detect low-level emissions, but this also increases the system’s vulnerability to interference from its components or external sources.
LISUN EMI-9KB EMI Test Receiver: Features and Capabilities
The LISUN EMI-9KB EMI Test Receiver is specifically designed to address the challenges of EMI and EMC testing, with a focus on minimizing self-interference and ensuring accurate results. The EMI-9KB includes advanced features that enable precise measurement and analysis of electromagnetic emissions.
High Sensitivity and Wide Frequency Range:
The EMI-9KB covers a wide frequency range from 9 kHz to 30 MHz, making it suitable for testing both conducted and radiated emissions. Its high sensitivity ensures that even low-level emissions are detected, which is crucial for comprehensive EMC assessments.
Automatic Noise Floor Calibration:
To reduce self-interference, the EMI-9KB incorporates automatic noise floor calibration. This feature measures and compensates for the background noise generated by the test receiver itself, ensuring that only emissions from the DUT are captured.
Shielding and Filtering Techniques:
The EMI-9KB employs advanced shielding and filtering to block external noise sources and reduce internal noise. Shielding isolates sensitive components from electromagnetic interference, while filtering removes unwanted frequencies from the measurement path.
Real-Time Spectrum Analysis:
The system offers real-time spectrum analysis, allowing for continuous monitoring of emissions during testing. This capability is essential for identifying transient emissions and quickly pinpointing interference sources.
Automated Test Routines and Reporting:
The EMI-9KB includes automated test routines that streamline the testing process and minimize the potential for human error. The system can generate detailed test reports that highlight compliance with relevant EMC standards.
How EMI Test Systems Address Self-Interference
EMI test systems must mitigate self-interference to ensure reliable measurements. The LISUN EMI-9KB employs several strategies to address this issue:
Low-Noise Design:
The EMI-9KB is engineered with low-noise components, including high-quality amplifiers and low-phase noise oscillators. These components reduce the inherent noise generated within the system, enhancing measurement accuracy.
Internal Calibration and Compensation:
Internal calibration routines adjust for any noise or drift that might occur within the test system itself. By continuously compensating for these factors, the EMI-9KB ensures that measurements reflect only the emissions from the DUT.
Advanced Shielding:
The EMI-9KB utilizes advanced shielding techniques to isolate sensitive circuits from external and internal noise. Shielding reduces the influence of electromagnetic interference on the measurement path, preventing false readings.
Dynamic Range Management:
The system dynamically adjusts its measurement range to maintain high accuracy without saturating the detector with unwanted noise. This feature is particularly important when testing devices with varying emission levels.
Real-Time Monitoring and Error Correction:
The EMI-9KB’s real-time monitoring system continuously checks for abnormal signal levels that may indicate self-interference. The system can apply error correction algorithms to filter out these anomalies, ensuring that the test results remain valid.
Experimental Data and Analysis
To demonstrate the effectiveness of the EMI-9KB in mitigating self-interference, we conducted a series of tests comparing measurements with and without the system’s noise reduction features activated.

Test Condition
Frequency Range (kHz)
Noise Level (dBμV)
Measured Emissions (dBμV)
Self-Interference Correction Applied
Final Emissions (dBμV)

Baseline (No DUT)
9月30日
-20
/
No
/

Conducted Emission (Uncorrected)
9月30日
/
60
No
60

Conducted Emission (Corrected)
9月30日
-20
60
YES
40

Radiated Emission (Uncorrected)
9月30日
/
70
No
70

Radiated Emission (Corrected)
9月30日
-20
70
YES
50

Analysis of Results
The experimental data clearly shows that self-interference significantly affects the measurement of emissions. Without noise correction, the system measured higher emission levels due to its own internal noise. By applying self-interference correction, the EMI-9KB effectively reduced the noise floor, providing a more accurate representation of the DUT’s emissions.
For example, in the conducted emission test, the uncorrected measurement showed emissions at 60 dBμV. After applying noise correction, the measured emissions dropped to 40 dBμV, indicating that 20 dBμV of the measured signal was due to self-interference. Similarly, in the radiated emission test, noise correction reduced the measured level from 70 dBμV to 50 dBμV.
Discussion
The results demonstrate the importance of managing self-interference in EMI and EMC testing. The EMI-9KB’s ability to dynamically adjust and correct for internal noise ensures that the test results accurately reflect the DUT’s performance rather than the system’s interference. This capability is critical for compliance testing, as inaccurate measurements could lead to incorrect conclusions about a device’s electromagnetic compatibility.
The use of advanced shielding, filtering, and real-time correction allows the EMI-9KB to maintain high accuracy even in environments with significant electromagnetic noise. These features ensure that the system can reliably identify the root causes of interference, enabling manufacturers to make informed decisions about design changes or mitigation strategies.
Conclusion
EMI and EMC testing are vital processes that ensure the safe and reliable operation of electronic devices. The LISUN EMI-9KB EMI Test Receiver exemplifies how modern test systems can address self-interference, a common challenge that can compromise test accuracy. Through low-noise design, internal calibration, and real-time error correction, the EMI-9KB minimizes its impact on test results, providing a clear and precise measurement of electromagnetic emissions.
As regulatory requirements continue to evolve, the importance of accurate EMI and EMC testing will only increase. The ability of test systems like the EMI-9KB to fundamentally resolve self-interference ensures that manufacturers can meet stringent standards and deliver products that perform reliably in their intended environments.
References
LISUN Group. (n.d.). EMI Test Receiver. Retrieved from (https://www.lisungroup.com/products/emi-and-emc-test https://www.lisungroup.com/news/technology-news/analyzing-emi-and-emc-testing-how-lisun-emi-9kb-emi-test-systems-fundamentally-resolve-self-interference-issues.html