Overview
ISO 21806-9:2020 - Road vehicles - Media Oriented Systems Transport (MOST) - Part 9 - is the conformance test plan for the 150‑Mbit/s optical physical layer (MOST150 oPHY). The standard defines measurement methods, operating conditions and test setups needed to verify that MOST optical networks, nodes and components conform to the physical‑layer requirements specified in the MOST family (referencing ISO 21806‑8). It targets the synchronous time‑division‑multiplexing (TDM) network used in automotive infotainment and vehicle multimedia systems.
Key topics and technical requirements
The document covers practical, test‑level requirements and measurement methods for the MOST150 optical physical layer, including:
- Operating conditions and measurement tools - required accuracy and apparatus for conformance testing
- Electrical interfaces - tests for LVDS and LVTTL signalling at relevant test points
- Optical characteristics - optical output/input power, pigtail fibre attenuation, spectral parameters, extinction ratio, overshoot/undershoot, transition times (measurements at SP2/SP3)
- Phase and jitter measurements - measuring alignment jitter (AJ), transferred jitter (TJ), phase variation and timing‑related tolerance (eye masks and jitter test set‑ups)
- Crosstalk and SNR - crosstalk measurement setups and signal‑to‑noise requirements for test equipment (Annex B)
- Power‑on / power‑off behaviour - EOC/OEC parameter measurements and test sequences for wake‑up and shutdown
- System performance & timing - receiver tolerance, TimingMaster delay tolerance, bit‑rate detection
- Conformance test flow - full and limited physical layer conformance procedures, parameter overviews, and component‑level verification (FOTs, pigtails, MOST devices, development tools)
- Annexes - informative and normative guidance (e.g., averaging measurements, SNR requirements, development tool conformance)
Applications and who uses it
ISO 21806‑9:2020 is used by:
- Automotive OEMs and Tier‑1 suppliers to validate MOST150 optical subsystems and ensure interoperability
- Component manufacturers (optical transceivers, fibres, FOTs, connectors) for product qualification and change control
- Conformance and test laboratories implementing physical‑layer certification for MOST networks
- Integration and verification engineers verifying jitter, eye mask compliance, crosstalk and power‑on behaviours in vehicle infotainment systems
Practical benefits include ensuring network compatibility, improving robustness of in‑vehicle multimedia links, and supporting standardized test evidence for supplier acceptance.
Related standards
- ISO 21806‑8 (requirements referenced by this test plan)
- Other parts of the ISO 21806 series covering MOST architecture and protocols
Keywords: ISO 21806-9:2020, MOST150 oPHY, conformance test plan, optical physical layer, automotive networking, jitter measurement, SP2 SP3, FOT, pigtail, LVDS, LVTTL.