- Rohde & Schwarz and TSN Systems offer a test solution that enables time measurements to be performed on automotive Ethernet networks with nanosecond accuracy on layers 1 to 3.
- The solution uses the R&S RTO oscilloscope from Rohde & Schwarz in conjunction with the TSN Box hardware network interface and the TSN Tools measurement and analysis software from TSN Systems.
Radar, lidar and other camera sensors in automobiles require the implementation of transmission systems that can transfer and process large volumes of data in milliseconds. Advanced Driver Assistance Systems (ADAS) must therefore be combined with communication systems that have high bandwidth and low latency. The Automotive Ethernet network meets these requirements in terms of data throughput and its ability to handle time-sensitive applications. Clock synchronization allows all devices on the network to operate in unison and perform the required operations at exactly the right time.
This test solution from Rohde & Schwarz and TSN Systems monitors an automotive 100BASE-T1 Ethernet communication link in which the TSN Box 3.0 interface acts as a talker, a listener and a test access point (TAP) that provides information to a PC with TSN tools based on layers 2 and 3. The TAP introduced 2x PHY delay for 100BASE-T1 at around 1.5 μs ±10 ns. The R&S RTO oscilloscope was used along with the R&S RTx-K35 bus measurements statistics option to measure and verify this timing accuracy in the physical layer of the automotive Ethernet signal (Layer 1). The mean time delay was measured to be precisely 1.5 μs with a max deviation of ±10.2 ns. In addition, the Qbv traffic (IEEE802.1) was generated by the TSN Box 3.0 with 500 μs cycle time resulting in a jitter ranging from 8 to 20 ns, which was verified by both the TSN Tools and the R&S RTO.
The solution, combining the software tools and the TSN Box interface from TSN System, provides various functions for the validation and testing of time-sensitive automotive Ethernet links. The PC-based TSN Tools analysis software provides visualization and analysis of the deeo data. The TSN Box interface, depending on its configuration, can act as a generic TSN Talker/Listener device with nanosecond accuracy. The Test Access Point (TAP) can synchronize seamlessly with the network’s gPTP master. This allows applications that need correlation between payload time stamps and TAP time.
The R&S RTx-K35 software option for the R&S RTO oscilloscope enables, among other things, the communication between two devices to be monitored over a long period of time. It provides statistics on error rates as well as on frame synchronization over packets. The R&S RT-ZF7 test interface serves as the central link for monitoring the oscilloscope between transmitter and receiver in both directions.
With the appropriate decoding option, the time data of the 100BASE-T1 link can be measured frame by frame to obtain bus error statistics such as frame error rate and rate of consecutive errors. In addition, time measurements can be performed for all automotive serial bus protocols: Automotive Ethernet, CAN, CAN-FD, LIN, I2C, etc.