struct ara::tsync::PdelayResponderMeasurementType

The data structure ara::tsync::PdelayResponderMeasurementType serves to bundle detailed time measurement data for the pDelay responder within time synchronization. It captures the arrival point in time of the request requestReceiptTimestamp [SWS_TS_14170] as well as the departure point in time of the response responseOriginTimestamp [SWS_TS_14171] in virtual local time along with the associated sequence number. An included reference global time tuple of virtual local and global time enables downstream systems to precisely convert the measured values into global time coordinates.

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Context

The data structure ara::tsync::PdelayResponderMeasurementType is defined in the header ara/tsync/time_validation_measurement_types.h and bundles precise time measurement data for the pDelay responder within the functional cluster of time synchronization (tsync). In the peer-to-peer transit time measurement procedure, the responder responds to transit time requests from neighboring network nodes. In order to be able to trace and validate the transmission delay in terms of time as well as the accuracy of the synchronization at link level, the structure captures the decisive timestamps of a measurement cycle. The unambiguous association with the triggering request message is ensured via the field sequenceId [SWS_TS_14174]. Interpretation: The collected measurement data are likely provided primarily for analysis and validation mechanisms (Time Validation) to monitor deviations and transmission delays in the network. Question Q-8e58febf465a0259 (open)

The captured timestamps comprise the exact arrival point in time of the request message requestReceiptTimestamp [SWS_TS_14170] as well as the departure point in time of the associated response responseOriginTimestamp [SWS_TS_14171]. Both values are represented as timestamps in virtual local time (Virtual Local Time). For uniform classification into the platform-wide time model, the structure additionally contains a reference time tuple: This consists of the local time value referenceLocalTimestamp [SWS_TS_14172] and the corresponding global time value referenceGlobalTimestamp [SWS_TS_14173]. Through this, processing entities can precisely convert the events measured in local virtual time into the global time scale.

Lifecycle

As a final struct declaration (struct ... final), PdelayResponderMeasurementType acts as a pure value object (Plain Old Data) without an internal state machine or dynamic memory management. An instance is typically created immediately after the completion of a pDelay transaction. Interpretation: Population of the structure is likely to take place synchronously in the responder's protocol stack as soon as all hardware and interface timestamps are available after sending the message Pdelay_Resp. Question Q-202e7724b43ceac9 (open)

With regard to ownership, the object is passed by value or via immutable references to downstream diagnostic or time validation routines. Since the structure manages no exclusive resources or pointers, the destruction process is trivial and tied to the scope of the calling context. With respect to concurrency, a fully initialized instance is thread-safe for concurrent read accesses; writing modifications require external synchronization if the instance is reused across threads.

Usage Path

The typical flow for capturing and providing the responder measurement data is divided into the following steps:

1. Reception of the request: Upon arrival of a Pdelay_Req frame, the responder captures the arrival point in time as requestReceiptTimestamp in virtual local time [SWS_TS_14170] and registers the associated sequence number sequenceId [SWS_TS_14174].
2. Transmission of the response: The responder transmits the response message Pdelay_Resp. When leaving the interface, the departure point in time is recorded as responseOriginTimestamp, likewise in virtual local time [SWS_TS_14171].
3. Determination of the reference tuple: To convert the measured values into global time, referenceLocalTimestamp [SWS_TS_14172] and referenceGlobalTimestamp [SWS_TS_14173] are determined from the current state of the local instance of global time.
4. Handover of the measurement data: The fully populated instance of PdelayResponderMeasurementType is handed over to the validation system, which checks the time differences and synchronization accuracies.

Sequence diagram: Flow of timestamp capture and measurement data provision at the pDelay responder. Sources: [SWS_TS_14170], [SWS_TS_14171], [SWS_TS_14172], [SWS_TS_14173], [SWS_TS_14174].