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Dear Natalie, Dear all, You have proposed two changes: 1)
go from UTP to STP, 2)
reduce from [15m/4] to [10m/2] which both will make PHY vendors life easier. The step from UTP to STP I understand very well, as we see what kind of effort we have to take to get UTP work on high bandwidth. The trade-off if we move away from UTP is that we will no longer have the chance of Auto-Neg, so the “family” of automotive Ethernet speedgrades will be split off into different physical layers.
However even if we move away from UTP - for now I would not focus on STP only, we may take into account STQ (star quad, using 2 pairs), Coax and optical as well. I got all the negative aspects of Coax and optical you have mentioned, but there are as well advantages (optical=no EMC, coax=higher bandwidth) for both systems and I’d like to understand
better the pro’s and con’s before I decide….
As well a 10Gbps link realized by 2x5Gpbs on two pairs would allow to use star quad for 10Gbps and STP for 5Gbps on one pair by defining 2 operation modes of the same PHY. We could leverage a more simple cabling for 5Gbps
with very few effort, if 5Gbps is sufficient. When we relax the EMC environment by using shielded solutions, I am not sure if it is useful to reduce from 15m to 10m as well: -
By using shielded cables (or more general: better channel), we relaxed the PHY design a lot, so 15m vs 10m is maybe not much difference for the PHy designers any more -
For now it may look like we do not have the right application which needs to go 15m through the vehicle with 10Gbps, however from a more general point of view I think we generate a “family” of automotive Ethernet
standards and it would be good to provide the same length on all standards to ensure some kind of “future-prove” similar behavior. -
As well I think we may have some vehicles (vans, busses) which may in the future as well upgrade from 1Gbps to 10Gbps and which are not satisfied with 10m So before relaxing both parts (Cabel type and length) I’d like to understand if really both steps are necessary. Gruß/Regards, Stefan Buntz |