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Differences: Synchronization in Time-Triggered Ethernet (SAE AS6802) compared to IEEE 1588
SAE AS6802 synchronization algorithm from uses a different approach compared to IEEE 1588 and its profiles (e.g IEEE802.1AS). The objectives and background of teams working on its development were diverse.

While IEEE1588 started within the data acquieituion and measurement industry, SAE AS6802 was developed from scratch to satisfy aerospace industry requirements - especially the requirements of fail-operational and advanced integrated architectures, including mixed criticality systems are taken into account.

Time Measurement
General diffrences in synchronization protocol and synchronization establishment are:

SAE AS6802 provides

system time

does not exchange timestamps

provides

.

Time Measurement
Time measurements is conducted by the of Sync/FollowUp and messages. By exchanging timestamps those messages may be used to measure wire delay, and determine average latency.

SAE AS6802 does not exchange any time between synchronization masters, but it can pass correction factors required for transparent clock. It measures the message arrival of the first bit of the first symbol, and based on so called permeance time (which describes maximum viable latency for acceptable synchronization message) determines the time.

Additional Services
Time measurements is conducted by the of Sync/FollowUp and messages. By exchanging timestamps those messages may be used to measure wire delay, and determine average latency.