In the digital age, DisplayPort (DP) cables, as the critical bridge connecting display devices and signal sources, play a vital role in the quality of audio and video transmission, device compatibility, and system stability. With technological advancements, VESA announced at CES 2025 a collaboration with members to launch the new DP80LL UHBR cables (DisplayPort 2.1b), extending the length to 3 meters through active cabling. NVIDIA is also actively cooperating with VESA to ensure optimal performance and compatibility between NVIDIA GPUs and DisplayPort 2.1b technology (including UHBR20 across DP80LL cables). This makes DP cable testing more urgent than ever.
Features of DP Cable Channels
DP cables contain multiple distinctive channels that work together to achieve high-speed signal transmission and device control functions, as detailed below:
Main Link
The Main Link is the core of the DP cable, responsible for the transmission of high-speed audio and video data. It uses four pairs of differential signal lines (Lane 0 to Lane 3) and supports video resolutions as high as 8K@60Hz. This multi-channel parallel transmission method greatly enhances data transmission bandwidth and efficiency, meeting the modern display devices' demand for rapid transmission of large amounts of data.
AUX Channel
The AUX Channel is tasked with transmitting control signals, such as EDID reading and HDCP key exchange. EDID reading enables the signal source device to obtain the display device's parameter information and output a signal format that best matches the display device. HDCP key exchange is the core of the digital content protection mechanism, preventing the illegal copying and distribution of high-definition video content.
HPD
The HPD (Hot-Plug Detect) channel is used to detect the connection status of devices. When a display device is connected to or disconnected from the signal source device, the HPD signal changes, triggering the system to respond accordingly, such as automatically recognizing the newly connected display device and making configuration adjustments. This enhances the system's ease of use and user experience.
Power
The Power channel provides stable electrical support for the logic circuits attached to the cable, typically outputting a 3.3V direct current voltage to ensure the normal operation of various electronic components within the cable.
Current Status of DP Cable Testing
To fully measure a DP cable, it is necessary to ensure the stability of the power and low-speed channels, as well as the signal integrity of the main link. For DP LRD cables, monitoring the cable's power consumption is also required. Currently, most DP cable manufacturers, considering cost, usually use computers and monitors that comply with the VESA Association's specifications for visual testing. However, this method is highly subjective and prone to omissions, and it does not allow for data storage. For manufacturers who are less cost-sensitive, they may use a wire sequence tester to confirm the low-speed channel and a VNA (Vector Network Analyzer) plus a switch matrix for SI (Signal Integrity) measurements (such as ILf, IRL, Xtalk, Skew, impedance, etc.). Although this can ensure quality, it is relatively inefficient and costly, and it also poses certain challenges for testing LRD cables. Of course, there is also a top-tier testing solution that uses a standard DP transmitter signal source paired with a real-time oscilloscope that can cost hundreds of thousands of dollars, but this solution is only used in the laboratories of large companies for LRD cables.
Telead Technologies’ Innovative Testing Solution
Faced with the confusion of measuring the new generation of high-speed DP cables, Telead Technologies, combining production testing needs and its own innovative testing, boldly attempted to integrate the testing of low-speed signal continuity, power consumption, main link sequence, and SI into a single CCBT20A-DP box. It supports the testing of DP 2.1/2.0/1.4 passive, LRD, and AOC cables. Especially for LRD and AOC cables, the integrated design allows customers to perform voltage rise and fall tests to check the robustness of the cables. It can also adjust the redriver chip of the LRD cable through the open interface provided by the customer, improving product performance and yield.
During the customer trial process, Telead Technologies carefully listened to customer suggestions and continuously upgraded and adjusted the product's precision and compliance. From the initial manual FFE of Tx to the current 1-14 Preset selection, and from the initial HF, LF CTLE settings to the current 0 to -9dB in the specifications, these improvements are the results of continuously perfecting the product according to customer needs. At the same time, Telead Technologies also applied the templates in the specifications to the eye diagram measurement to judge the performance margin of the cable.
Even now, Telead Technologies continues to optimize product performance and precision under the impetus of customers and further passes on professional knowledge of the time domain and frequency domain to a wide range of customers, providing more choices. With rich production line measurement experience, Telead Technologies clearly understands the difference between engineering and production testing, so it has made production testing a one-key scanning operation, with software automatically judging pass/fail and data directly uploaded to the database. Currently, the CCBT20 series of products can cover the measurement of passive and active cables of USB4, TBT5, HDMI2.2, DP2.1, and other series. If you have any questions about Telead Technologies’ CCBT20A-DP testing solution, or want to share your testing experience, please leave a message in the comment area. We will answer you in the first time! For more information on testing solutions for consumer cables and devices or customized development solutions for data communication, you can directly contact Telead Technologies at sales@te-lead.com , and also follow its official account to keep up with the latest testing solution information.