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Electromagnetic Compatibility (EMC) refers to the ability of equipment or systems to operate normally in their electromagnetic environment without generating unacceptable electromagnetic interference to other devices in that environment. Its core consists of two interrelated requirements: first, controlling the electromagnetic interference (EMI) generated by the equipment itself; second, enhancing the equipment's immunity to external electromagnetic interference (Electromagnetic Susceptibility, EMS).
For audio and video products, their functional characteristics such as high-frequency signal processing (e.g., HD video codec, RF module operation) and multi-device interconnection (e.g., cascading via HDMI, USB interfaces) expose them to dual risks in terms of electromagnetic compatibility:
The mandatory requirements for electromagnetic compatibility (EMC) testing of audio and video products are based on the core logic of standardizing electromagnetic environment management through unified standards, ensuring that products can operate normally in complex electromagnetic environments without causing interference to other devices or systems.
EMC Requirements in Major Global Markets
The EU requires products to comply with EN 55032 (electromagnetic emissions) and EN 55035 (electromagnetic immunity) standards through the CE certification system; the US FCC restricts electromagnetic emissions of audio and video products through Part 15B regulations; China mandatorily implements the GB 9254.1-2021 standard through CCC certification.
EMC testing is a core link in ensuring the quality and reliability of audio and video products, serving as the "touchstone" for product quality. Through dual verification of electromagnetic interference (EMI) testing and electromagnetic immunity (EMS) testing, it systematically controls the product's electromagnetic disturbance to the outside world and enhances its own anti-interference capability.
EMS testing evaluates its immunity performance through strict criteria: Criterion A requires no functional loss during testing, Criterion B allows temporary functional loss that can recover automatically, Criterion C requires manual intervention for recovery, and Criterion D is defined as unrecoverable due to damage or data loss.
As consumer electronic devices, the core value of audio and video products lies in providing users with an "interference-free" experience, such as audio output without noise, video pictures without snow or interference stripes. Electromagnetic compatibility (EMC) testing is a key link in guaranteeing this core value.
Audio without Noise
Picture without Snow
No Signal Interruption
No Functional Abnormalities
The international general electromagnetic compatibility (EMC) standard framework is characterized by "generality" and "fundamentality," providing a unified template and methodological benchmark for global product testing through a series of standards developed by international standardization organizations.
Among them, the CISPR series of standards developed by the International Special Committee on Radio Interference (CISPR) and the IEC 61000 series of standards published by the International Electrotechnical Commission (IEC) constitute the two pillars of this framework:
In the development process of the domestic electromagnetic compatibility standard system for audio and video products, efforts have always been made to balance the needs of "internationalization" and "localization," both by adopting advanced international standards to ensure alignment with the global technical system and by retaining necessary characteristic requirements based on domestic market characteristics.
GB/T 9254.1-2021 "Information technology equipment, multimedia equipment and receivers - Electromagnetic compatibility - Part 1: Emission requirements," as a mandatory certification standard for electronic products and safety accessories, was released on December 31, 2021, and officially implemented on July 1, 2022, comprehensively replacing the old versions GB/T 9254-2008 and GB/T 13837-2012.
| Country/Region | Certification Name | Test Type | Main Standards |
|---|---|---|---|
| European Union | CE Certification | EMI+EMS | EN 55032, EN 55035 |
| United States | FCC Certification | EMI | FCC Part 15B |
| China | CCC Certification | EMI+EMS | GB 9254.1-2021 |
| Australia/New Zealand | RCM Certification | EMI | AS/NZS CISPR 32 |
| Canada | IC Certification | EMI | ICES-003 |
| Japan | MIC Certification | EMI | J55032 |
Key components such as switching power supplies and high-frequency chips inside audio and video products generate electromagnetic interference signals during operation. These interferences can be conducted to the public power grid through power lines and signal lines, potentially affecting the normal operation of other electrical equipment (such as refrigerators, air conditioners) in the grid.
Test Frequency Range: 150kHz~30MHz
Radiated emission is one of the most easily exceeded items in electromagnetic compatibility testing for audio and video products. Its core technical key points are reflected in three aspects: test environment simulation, frequency coverage range, and high-frequency component interference control.
Test Frequency Range: 30MHz-6GHz (can be extended to 26MHz~3GHz in some scenarios)
The harmonic current and voltage fluctuation & flicker test is a key link in ensuring power grid safety and public interest, mainly evaluating the harmonic pollution and voltage fluctuation impact of audio and video products on the public power grid, ensuring "green power consumption" of the equipment.
The Electrostatic Discharge (ESD) immunity test is an important part of the electromagnetic immunity testing system. Its core goal is to simulate the electrostatic interference that may occur when users come into contact with audio and video equipment in real scenarios.
Contact Discharge Levels: ±2kV, ±4kV, ±6kV, ±8kV
The RF electromagnetic field radiated immunity test is a key means for audio and video products to cope with complex electromagnetic environments. In the actual usage scenarios of audio and video products, there are numerous RF sources, such as mobile phones, base stations, and other radio equipment.
Field Strength Typically 3V/m or 10V/m
The Electrical Fast Transient/Burst (EFT) and Surge immunity test is an important part of the electromagnetic immunity testing for audio and video products, mainly simulating common transient interference in the power grid environment.
The high precision and reproducibility of EMI testing rely on the collaborative work of four core types of equipment: EMI receiver, LISN (Line Impedance Stabilization Network), antenna, and anechoic chamber. Each equipment performs specific functions to achieve accurate capture and quantitative analysis of electromagnetic interference signals.
Core EMS testing equipment verifies the immunity capability of audio and video products in complex electromagnetic environments by simulating real electromagnetic interference environments, ensuring the consistency of test results with actual application scenarios.
The accuracy of EMC test results highly depends on strictly controlled testing environments and equipment calibration processes. Environmental factors and equipment precision directly affect the reliability of test data. If the environment has interference or the equipment is not calibrated, it may lead to misjudgment of the product's electromagnetic compatibility.
| Site Type | General Usage Frequency | Structural Characteristics |
|---|---|---|
| Semi-Anechoic Chamber (SAC) | 9kHz~18GHz | Standard shielding structure |
| Open Area Test Site (OATS) | 30MHz~18GHz | With weatherproof cover |
| Free Space Open Area Test Site (FSOATS) | 30MHz~18GHz | Flat, open area with uniform and good conductivity |
| Full Anechoic Chamber (FAR) | 400MHz~40GHz | Fully lined with absorbing material |
Enterprises commonly have the misconception of "focusing on function realization while neglecting EMC design" in the development of audio and video products. Such cognitive bias may lead to significant commercial risks.
A typical case shows that a brand of smart TV failed to meet radiated emission standards (field strength in the 30MHz-1GHz frequency band exceeded the EN 55032 standard limit by 5dB), was denied access to the EU market, required redesign of shielding and filtering circuits, directly causing a 3-month delay in the launch plan and economic losses exceeding 5 million yuan.
From an industry commonality perspective, products that do not comply with EMC standards will face multiple commercial risks, including blocked access to target markets, damage to brand reputation, and potential legal risks.
Current EMC testing technology is showing multi-dimensional development trends, which have a profound impact on the testing capabilities, efficiency, and compliance of audio and video products.
As a key link in the full lifecycle management of audio and video products, the necessity of Electromagnetic Compatibility (EMC) testing can be systematically explained through the logical closed loop of "regulatory requirements - quality experience - technological competitiveness".
Establish a dynamically updated "standards database" and deepen cooperation with third-party professionals
Early preliminary testing is a key link, capable of discovering 80% of EMC problems
Systematically advance from multiple dimensions such as basic laboratory configuration and design source optimization
