AUTOMOTIVE
Automotive Ethernet: Driving the future of in-vehicle connectivity
Jithu Abraham, product manager oscilloscopes at Rohde &Schwarz presents the latest solutions for future onboard networks
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utomotive Ethernet covers a family of standards that have been developed to adapt Ethernet technology to the requirements of vehicle connectivity. The latest MultiGBASE-T1 version is especially powerful and challenging, but it can be reliably implemented in market-ready products using an automatic test solution. Automotive Ethernet has become the de facto standard for vehicle connectivity. Since its breakthrough with BroadR-Reach technology, this robust, lightweight and compact standard enables the transmission of large data volumes at up to 100Mbit/s from sensors to control units in line with automotive EMC standards.
Current trends such as autonomous driving, active advanced driver assistance systems (ADAS) and telematics services, however, require significantly faster transmission technologies. Enormous amounts of data from a growing number of sensors and high- resolution cameras must be transmitted from various places in the vehicle. Safety critical technologies like active ADAS and vehicle to everything (V2X) additionally require low latencies for real-time communications. Greater bandwidths are also needed to pave the way for onboard networks with a zonal architecture. This is possible by enabling fast connection of local domain controllers to a backbone.
A new standard for future onboard networks
MultiGBASE-T1, as the next evolutionary step of automotive Ethernet, has been developed to meet these rising performance requirements. It is fully based on IEEE 802.3ch, specifies three speed levels (2.5Gbit/s, 5Gbit/s and 10Gbit/s), and operates in full duplex mode. It supports autonegotiation (independent negotiation of transmission conditions), and is therefore completely backward compatible. Unlike 100BASE-T1 and 1000BASE-T1, the
10 MARCH 2022 | ELECTRONICS TODAY
FIGURE 1:The R&SRTP164 oscilloscope with 16GHz bandwidth – shown here connected to an automotive domain controller – is suitable for compliance tests of all transmission rates specified in MultiGBASE-T1
based communications in the automotive sector. The Physical Media Attachment (PMA) specification is now in the development stage, with the strong participation of Rohde & Schwarz as a member of the tech committee.
Automated compliance test solution
Figure 2: Comparison of automotive Ethernet standards
new multi-gigabit standard utilises PAM4 modulation with four discrete voltage levels and symbol rates of 1.4Gsymb/s, 2.8Gsymb/s, or 5.6Gsymb/s (Figure 2). It also requires shielded twisted pair (STP) cables, unlike its slower predecessors that could manage with unshielded twisted pair (UTP) cables. The IEEE published the new standard at the end of June last year, and the first chips and interfaces (PHY) are already on the market. MultiGBASE-T1 interoperability and compliance testing are being addressed by the new tech committee TC15 of the Open Alliance Special Interest Group, which is dedicated to the promotion of Ethernet
Control units and chipsets must fulfill the PMA transmitter test specification to demonstrate compliance with the standard. For this, Rohde & Schwarz offers a fully automatic test solution with the new R&SRTx-K88 options for the R&SRTO and R&SRTP oscilloscopes (Figure 1). The R&SRTP is suitable for testing data rates up to 10Gbit/s, which covers all rates specified in the standard, while the R&SRTO is suitable for data rates up to 2.5Gbit/s. The solution supports all transmitter tests defined in IEEE 802.3ch, such as jitter, transmitter linearity, output droop, etc. The test solution also includes the R&SZND or R&SZNB vector network analyser for MDI return loss measurements. The solution is built around the
R&SScopeSuite test software (Figure 3), which controls the devices, configures them for the respective tests and calculates the results. A
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