Renesas enables HD video over SD cables for automotive cameras
Automotive manufacturers can deliver high definition (HD) video over low cost cables and connector that currently support standard definition video, by using the Automotive HD Link (AHL) from Renesas.
The RAA279971 AHL encoder and RAA279972 decoder use a modulated analogue signal to transmit the video, for transmission rates 10 times less than required to transmit HD signals digitally. The lower transmission rate means that traditional twisted pair cables and standard connectors and existing analogue video cables and connectors can be used.
Digital links such as SerDes require heavily shielded cables and high end connectors that cost significantly more than those for AHL. Additionally they may need to be replaced in five to seven years. They are also difficult to route because of a limited bending radius.
AHL is robust against noise and has a bi-directional control channel that operates independently of the video data, says Renesas. It can initialise, program and monitor the camera module. The camera can be controlled simultaneously over the same pair of wires (UTP) during video transmission to reduce the cost of installation. 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 will present a slight change in video colour or contrast, but all pixels will appear on the screen. The resulting image will accurately identify an object or person behind the vehicle.
According to Renesas, the AHL system allows automotive manufacturers to deliver advance safety systems in all vehicles, including economy models and not just luxury ones.
AHL supports resolutions from VGA up to 720p/60 or 1080p/30 enabling it to implement non-standard vertical resolutions.
There are also MIPI-CSI2, BT656, and DVP inputs and outputs to provide a flexible interface to support old and new image sensors.
The RAA279971 AHL encoder and RAA279972 decoder are available today. Renesas also offers the RTKA279971DA2000BU AHL encoder and the RTKA279972DA1000BU AHL decoder evaluation boards.
