As I run a university program for a semi company, private email me at firstname.lastname@example.org and I may be able to get you some devices etc. if needed for your research.
Having worked in the automotive arm of a major FPGA supplier, I can vouch for how long it takes to get a new technology accepted. 5-10 years or so. I started calling on automtive customers in 1995 and FPGAs were too exepensive and too "new" for automotive. Now they are almost (but not quite) mainstream.
Thanks, Docdivakar. Another thing we need to keep in mind is that those HD video streams used in automotive safety apps are, I assume, not for human to watch pretty pictures but for machine vision -- to make a judgement if there is any "danger."
The comment turned out to be a bit longer than intended...
The delays are of course related to the buffer size of the decoder. This depends heavily depend on the reliability of the network, the speed of the decoding machine and many other factors. In our tests these delays varied around 1-2 seconds for strong desktop computers and over 3 seconds for mobile devices. We did not do any more accurate measurements, as this was already defeating the pupose of a park assistant camera for us.
Thank you Junko for a nice article shedding a bit of light inside the usually top secret automotive Ethernet domain. Also thanks everyone for the interesting discussion. In fact I registered just now to contribute here.
I am currently building an infotainment system for an academic research vehicle (TUM CREATE EVA, www.tumcreate.edu.sg). We are also including HD cameras (front & back). We stumbled across a few problems when using compressed streams, depending on the stream format. When using H.264 streams, there is always a certain buffer needed to decode the stream. This buffer comes with a certain delay. Especially for real-time parking cameras this is deadly.
I could imagine that this is where car manufacturers are coming from when asking for uncompressed video. Their requirement might be a short delay.
We instead use MJPEG coding, which allows us to reduce the stream delay to a minimum.
All in all: Once understood, it is for sure possible to combine the requirements of the automotive industry with the technologies already in the market, to be able to transfer real-time video while using small bandwidth.
One more comment regarding Ethernet switches, as this also touches on my research: The amount of switches is indeed not a good measure, however, comparing Ethernet to CAN, one might consider a switch overhead for the communication system. Those devices of course consume power and weight, which is all unwanted by the automotive industry.
However, I am fully with Bert in rather using many smaller switches instead of one big switch, especially for in-vehicle networks. One big switch would introduce more and longer heavy cables, while multiple smaller switches introduce latency. One needs to compare these elements and decides for a good structure.
@Chan: Daisy-chains are not necessarily bad, they can actually bring advantages, when networked correctly with the rest of the system. Pure daisy-chains I would avoid though. And I fully agree, there will be new topologies and routing strategies necessary for vehicles! The need is definitely there.
One last comment in my own interest: We will be unveiling our purpose-built electric taxi EVA on the Tokyo Motor Show 2013 in November. Feel free to come by TUM CREATE booth, if any of you are there. I would love to discuss these topics in more detail!
Junko & Bert: good points. I do agree it will require much more than 1.5Gbps to broadcast color videos. Bert is also right in bringing out a metric that matters which is the number/redundancy of hosts. At the bare minimum, there needs to 2 or more depending on the location in the vehicle and the corresponding failure rates FITs.
Regarding uncompressed video, most industrial ethernet cables & connectors (M6, M12) use gigabit ethernet which will not be sufficient for color video. But then again, video used in navigation can be of lower resolution to utilize what is available as bandwidth.
Junko, when I hear things like "don't want to compress video streams" or "must have isochronous network," I flat don't believe it. Sounds close to knee-jerk position statements, bound to evolve as people design these things.
Uncompressed HD video, just one stream, would require 1.5 Gb/s just for black and white video. That's just one stream. A Gigabit Ethernet network wouldn't even be able to handle a single B&W camera.
January 2016 Cartoon Caption ContestBob's punishment for missing his deadline was to be tied to his chair tantalizingly close to a disconnected cable, with one hand superglued to his desk and another to his chin, while the pages from his wall calendar were slowly torn away.122 comments