Apr 20, 2016 
RUETZ SYSTEM SOLUTIONS – experts in automotive data communications – now also provide coaxial physical layer testing for MOST150. The recently developed MOST Tester Cable Model "MTCM" is an extension of the well-proven Physical Layer Stress Test Tool "PhLSTT". "Our new MTCM meets the additional challenges and demands for physical layer testing that arise with the newly introduced coax physical layer for MOST150," stated Wolfgang Malek, General Manager and Co-Founder of RUETZ SYSTEM SOLUTIONS. "With the MOST Tester Cable Model, we provide a highly integrated solution to implement a MOST150 limited cPHY test setup, meeting all requirements specified in the MOST150 cPHY Compliance Verification Procedure." Simple to apply, the MTCM allows easy migration cPHY from an existing MOST150 limited oPHY test setup to a MOST150 limited cPHY test setup in combination with the PhLSTT. The cPHY physical layer provides 50 Ohm coax connections for simplex and duplex transmission. The main purpose of the MTCM is to emulate a transfer function, which represents typical coax interconnections in a car. The PhLSTT creates the MOST150 pattern that feeds the device under test (DUT).
Automating the MOST150 cPHY Test Setup
An internal microcontroller regulates all functions of the MOST Tester Cable accessed by a serial interface. A documented application-programming interface is available. Thus, RUETZ SYSTEM SOLUTIONS provides a fully automated solution that incorporates the complete MOST150 limited cPHY test setup. It consists of the Physical Layer Stress Test Tool, the MOST Tester Cable Model, a power supply, and an optional temperature chamber.
Testing Common In-Vehicle Use Cases
The test system defines three different cable models in order to simulate a transmission channel, thus covering typical use cases in the car. A transmitter with adjustable rise and fall times drives these cable models, which represent a short, mid and long transmission line. For duplex operation, an integrated coupler separates the incoming signal from the outgoing. Thereby, this signal can be used for oscilloscope measurements and a return path to the PhLSTT. In terms of measuring MOST signals, the cPHY technology offers the advantage of the transmission system to be terminated by 50 Ohms and therefore an oscilloscope can directly connect to it without an additional probe. The MCTM provides a test solution for simplex as well as for duplex operations. For duplex operations, an additional noise input is available to connect an external signal source to the MTCM. The design of the MTCM allows various input signals, either single-ended or differential signals, as provided by SMA or HSD connectors, with HSD allowing direct connection to the PhLSTT.
