Optoelectronics

Automotive HD Link enables high-def using low-cost cables

19th July 2021
Alex Lynn

Renesas Electronics has introduced its new Automotive HD Link (AHL) technology that enables automotive manufacturers to deliver high-definition video over low-cost cables and connectors that currently support standard-definition video. HD video is increasingly important in car safety systems for object recognition functionality.

Renesas is a leader in the Advanced Driver Assist Systems (ADAS) market, and AHL can be paired with other Renesas products, such as the R-Car Automotive SoCs, RH850 MCUs, automotive PMICs, and analog components to cost-effectively implement numerous safety features in virtually any vehicle.

The new RAA279971 AHL encoder and RAA279972 decoder use a modulated analog signal to transmit the video, enabling transmission rates ten times less than required to transmit HD signals digitally. The lower transmission rate means that traditional twisted pair cables and standard connectors can be used, as can existing analog video cables and connectors.

On the other hand, digital links such as SerDes require heavily shielded cables and high-end connectors that cost significantly more than those for AHL, may require replacement after five to seven years and are difficult to route due to bending radius limitations.

AHL is robust against noise and has a bi-directional control channel that operates independent of the video data and can initialise, program, and monitor the camera module. A key AHL performance and cost reducing feature is the ability to control the camera simultaneously over the same pair of wires (UTP) during video transmission.

Another safety benefit of AHL is its performance in comparison to a digital link. In a rear view camera application, a digital link will degrade due to a failure in the cable harness or connector assembly, as weak signals can cause macroblocks to appear, hiding large portions of the viewing area. Using the same cable under the same conditions for comparison, the AHL link will present a slight change in video color or contrast, but all pixels will appear on the screen, and the image will precisely identify an object or person behind the vehicle.

“Advanced safety systems are no longer only available in luxury vehicles,” said Niall Lyne, Vice President of the Automotive Analog Power and Video Business Division at Renesas. “The AHL system enables our automotive customers to now deliver these features in all new vehicles, including economy models.”

Key features of AHL

  • Supports resolutions from VGA up to 720p/60 or 1080p/30 for flexibility to implement non-standard vertical resolutions (not just the TV video standard 16:9 resolutions).
  • MIPI-CSI2, BT656, & DVP inputs and outputs provide flexible interface to support old and new image sensors.
  • Requires only 27MHz crystal clock, with internal PLLs able to generate the necessary clock frequencies for higher resolutions.

Availability

The new RAA279971 AHL encoder and RAA279972 decoder are available today. Renesas also offers the RTKA279971DA2000BU AHL Encoder and the RTKA279972DA1000BU AHL Decoder evaluation boards.

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