With the widespread adoption of 4K and 8K high-resolution AV content and the rapid growth of streaming media services, the demands for AV transmission quality have risen. HDMI 2.1, as the next-generation AV interface, has become an essential component for high-end AV equipment due to its high bandwidth, high resolution, and eARC features. However, in practical applications, HDMI 2.1 cables often face issues such as signal attenuation and noise interference, significantly impacting the user’s AV experience.
High-End AV Generation: Specifications and Demands of HDMI 2.1
HDMI 2.1 cables are widely used in consumer electronics, particularly high-end AV equipment and gaming consoles. As consumer expectations for AV quality rise, so do the performance requirements for HDMI 2.1 cables.
- High-Resolution Demands: The proliferation of 4K and 8K high-resolution AV content imposes stricter requirements on cable bandwidth and signal integrity.
- High-Quality Audio Requirements: The introduction of eARC technology necessitates HDMI cables that support higher bit rates and multi-channel lossless audio.
- Reliability Requirements: Consumers expect HDMI cables to operate reliably and consistently, avoiding issues such as signal attenuation and noise interference.
HDMI 2.1 specifications meet these upgraded expectations by supporting resolutions up to 10K and refresh rates up to 120Hz, while also delivering high-quality audio. For high-end AV enthusiasts, a high-quality HDMI 2.1 cable is essential.
As a result, consumers expect higher standards of quality and performance when selecting HDMI cables. Manufacturers must adhere to stringent certification and testing procedures to ensure each cable meets the required standards and delivers the best possible AV experience for users.
Challenges for Manufacturers: eARC Signal Loss Issues
However, with the widespread adoption of eARC (Enhanced Audio Return Channel) technology, many HDMI 2.1 cable manufacturers are facing new challenges. Among these challenges, signal loss in eARC transmission has become a significant issue troubling the industry.
Allion has collaborated with several major cable manufacturers to address eARC issues with HDMI 2.1 cables. For example, a new HDMI 2.1 cable developed by a client exhibited excessive signal loss during eARC functionality tests. The client’s team attempted to analyze the problem independently, but due to the potential sources of signal loss—such as design, components, or manufacturing processes—they could not precisely identify the root cause of the issue. Faced with this challenge, the client sought Allion’s professional assistance, hoping for in-depth analysis and effective solutions.
Solutions
As shown in Figure 1, the HDMI 2.1 cable developed by the client exhibited severe signal attenuation issues in the eARC channel’s frequency response test, specifically within the 300 kHz to 200 MHz frequency range. Particularly at the critical frequency of 100 MHz, the signal attenuation reached unacceptable levels, directly causing the product’s test to fail.
Figure 1: eARC Differential Insertion Loss Test Standards and Actual Improvement Cases
The Allion high-frequency testing team conducted an in-depth analysis of the client’s sample and, in conjunction with the process information provided by the client, identified the root cause of the issue: poor processing of the bare wires.
- Root Cause Analysis: HDMI cables contain multiple small conductors, and manufacturers typically use plastic channels to secure these conductors for easier production. However, in this case, the design and manufacturing process of the channels had defects, leading to excessive compression and bending of the conductors within the channels. This caused increased contact resistance, resulting in severe signal attenuation during high-frequency transmission. Additionally, inconsistent stripping lengths exacerbated the problem.
- Improvement Recommendations and Validation: Allion recommended that the client make improvements in the following two areas:
- Optimize Channel Design: Adjust the shape and size of the channels to ensure adequate space for the conductors, avoiding excessive compression and bending.
- Strictly Control Stripping Lengths: Establish standardized stripping processes to ensure consistent stripping lengths for each conductor, preventing poor contact due to overly long or short stripping.
The client implemented Allion’s recommendations and resubmitted the samples for testing. The results showed a significant improvement in signal attenuation for the eARC channel, with the revised samples fully meeting the product’s design requirements.
Table 1: eARC Differential Insertion Loss Test Standards and Actual Improvement Cases
Time to Market with Quality! High-Quality Service to Create Value for You
Faster, Easier, Better! The Three Key Values of Allion’s Services to Accelerate Your Product’s Time-to-Market with Quality
Allion adheres to the “Faster, Easier, and Better” service philosophy to help clients overcome challenges in product development and testing, accelerating their time-to-market with quality.
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- Advanced Testing Equipment: Allion is equipped with a comprehensive array of testing tools, including network analyzers, oscilloscopes, and microscopes, to precisely measure product performance. This enables us to quickly diagnose issues and provide actionable improvement recommendations to help clients accelerate their development and testing processes.
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- Precise Problem Identification and Improvement Recommendations: Using advanced testing equipment and experienced engineers, Allion quickly identifies the root causes of issues, offering clients precise analysis reports and guidance on optimization. For instance, in one case, a client struggled for nearly three months to resolve an issue internally, while we provided corrective recommendations and support for resolution and verification within a week.
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- Extensive Experience: Allion has accumulated years of testing experience, allowing us to provide comprehensive testing advice and reduce clients’ trial-and-error time.
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Better
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- Professional Team: Allion’s engineers possess deep expertise and extensive practical experience, providing clients with professional technical consulting.
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- Complex Environmental Testing: Beyond standard testing, we simulate various complex environmental conditions to conduct thorough product testing, ensuring product reliability.
- Custom Testing Solutions: Allion tailors custom testing solutions based on clients’ specific needs, meeting a wide range of complex testing requirements.
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