Overview
ISO 21806-10:2021 specifies the 150-Mbit/s coaxial physical layer (MOST150 cPHY) for Media Oriented Systems Transport (MOST) in road vehicles. It defines the physical-layer interfaces, constraints, and parameter values needed to develop products such as coaxial links, coaxial transmitters/receivers, and electrical↔coaxial converters. The standard also establishes basic measurement techniques and test methods for verifying MOST150 cPHY performance in synchronous time-division-multiplexing (TDM) MOST networks.
Key topics and technical requirements
The document covers practical and testable requirements for implementing MOST150 cPHY, including:
- Physical layer service interface to the OSI data link layer (events, requests, parameters).
- Basic physical-layer requirements: logic terminology (single‑ended low‑voltage digital and differential LVDS), specification points (SPs), and phase variation topics such as wander, jitter, clock recovery and reference clock behavior.
- MOST150 cPHY-specific requirements: network coding, link and interconnect types, analogue front-end and transceiver integration.
- Measurement models and methods: golden PLL, jitter filter, retimed bypass mode and stress patterns for validating link tolerance.
- Link and interconnect specifications: coaxial attenuation, characteristic impedance, return loss, cable length constraints, and SP definitions for different test conditions.
- Power sequencing and safety: frequency reference, power-on/power-off behavior, and requirements for coaxial transceiver control (ECC/CEC) during power transitions.
- Network topologies and device interfaces: daisy-chain structures, 2‑port node behavior, connector guidance and timing master delay tolerances.
- Environmental and compliance considerations for automotive deployment.
Practical applications and who uses this standard
ISO 21806-10:2021 is targeted at professionals and organizations designing, manufacturing, testing, and integrating in-vehicle multimedia and infotainment systems:
- Automotive OEMs and system architects defining MOST networks.
- Semiconductor and transceiver manufacturers building MOST150 coaxial PHY silicon or modules.
- Cable and connector suppliers validating coaxial interconnects for automotive use.
- Test laboratories and compliance engineers verifying jitter, return loss, attenuation and power sequencing per SPs.
- Integration engineers implementing daisy-chain topologies for audio/video distribution and low-latency control signals.
Adopting MOST150 cPHY enables reliable, low-latency synchronous streaming of audio, video and real‑time control over a coaxial medium in automotive environments.
Related standards
- Other parts of the ISO 21806 series (Media Oriented Systems Transport) for data-link, network and application level aspects.
- Reference to broader networking standards such as ISO/IEC/IEEE 8802-3 (Ethernet) appears in the standard’s introduction for integrated automotive communication contexts.
Keywords: ISO 21806-10:2021, MOST150 cPHY, 150-Mbit/s coaxial physical layer, Media Oriented Systems Transport, automotive coaxial PHY, LVDS, jitter, daisy chain, coaxial transceiver.