Page 18 - EngineerIT November 2021

AUTOMOTIVE ELECTRONICS

Car Camera Bus (C2B) - Cost-efficient

camera connectivity

By Paul Slattery

utomotive camera connectivity is a HD cameras often use coax cables, which are expensive, heavy, and difficult to route through
significant cost addition for camera small spaces. SVMs using coax cable harnesses require expensive coax connectors, resulting in
Aapplications, but it enables new several million dollars of additional system costs to automotive OEMs. The industry is faced with a
safety and comfort features. The latest significant question: what video interface from the camera provides the optimised cost point?
market research estimates each vehicle will
have an average of four cameras by 2024 Staying with an SD solution is not an option
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as the market responds to consumer and Standard definition (SD) cameras have been used in the majority of automotive camera designs for
regulatory demands. New applications such many years. They use a low cost cable and connector infrastructure to minimise the system cost of
as surround view monitoring (SVM), driver the SVM module. SD camera systems, however, are often only compliant to 100 mA bulk current
status monitoring (DSM) and drive recording injection (BCI), and most OEMs today require 200 mA BCI performance. As in-cabin display sizes
are at the forefront of this explosion in increase, the visual performance of SD becomes problematic. SD video (720 × 480) is very small
camera technology. SVM and rear-view size and needs to be scaled to fit modern automotive displays (for example, 1920 × 720). Scaling
cameras enable safer parking. DSM cameras involves interpolating or creating new pixels to fill the space. This interpolation process causes
are used to monitor the driver’s position many visual artifacts including, for example, jaggies on diagonal lines. Consumers are accustomed
and eye movements to detect and prevent to HD camera performance in their smartphones, and SD performance is no longer acceptable.
driver distraction. Drive recording cameras Although SD video provides a very low cost solution, many OEMs are planning to remove SD
are used to record accidents. DSM and cameras from all models by 2025 because of the limited EMC/I (BCI) and video performance.
drive recording cameras are mandated in
UN regulations on automated lane keeping LVDS is a costly option
systems (ALKS), which came into force Low voltage digital signalling (LVDS) camera links provide a high performance albeit expensive
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in January 2021. More than 60 countries solution for automotive HD cameras. LVDS is a digital serial transmission scheme and accurately
have adopted ALKS, which utilises Level 3 transports video from the camera to the electronic control unit (ECU). LVDS camera solutions
vehicle automation (autonomous features are ideal for high end, front-facing cameras at 4 to 8 megapixels. Front-facing cameras require
that require the driver to be able to resume the highest video resolution in automotive cameras to support adaptive cruise control, object
driving when requested) to keep the detection, traffic sign recognition and collision avoidance. LVDS uses high bandwidth and requires
vehicle within its driving lane. DSM is also shielded cables to pass automotive EMC and EMI testing. LVDS links typically use coax and mini-
a fundamental requirement of the Euro coax cables. The bend ratio of these cables and the robustness to many bend cycles make the
NCAP 2020 assisted driving rating system. 3 manufacturability of these cables a problem for automotive OEMs - for example, when routing
The automotive manufacturing industry is cables through door hinges to mount cameras on mirrors, or in the ceiling of the vehicle for
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already one of the most heavily indebted
and lowest margin industries globally. The
challenge for the industry is how to provide
the required camera performance without
adding significant cost.
SVM camera systems provide a 360°
view around the outside of a car when
parking. These systems help decrease the
risk of low speed accidents, particularly
with pedestrians and blind pedestrians. Up
to 70% of vehicles will have SVM installed
in Asian countries where congested streets
and small parking spaces make parking
especially difficult. SVM is a great example
of a camera application that saves lives and
creates a first-rate driving experience. SVM
also makes an interesting case study for the
performance-cost analysis of automotive
camera systems. Each SVM system uses
four cameras to create the panoramic view. Figure 1: Camera and connectors for C2B in a car.

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