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IEEE 1588-2019 pdf free download
IEEE 1588-2019 pdf free download.IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems.
Implementations that generate PTP timestamps at the physical layer need to take the mapping to the on-the- wire format (see 5.4) into account when designing packet recognizers, timestamp generators. and any other form of hardware assist to PTP that is done at the physical layer.
It is possible to design PTP Nodes where the timcstamps arc generated between the MAC layer and the PHY or even within the PI-IY. In such PTP Nodes, it is likely that all or part of the PTP timestamping will be embedded and executed within low-level silicon without the USC of an operating system.
6.6.6 Potential errors in measuring path delays and residence time
18.104.22.168 Potential errors in measuring path delays and residence time due to differing rates of the Timestamping Clocks in PTP Instances in a domain
Errors in measuring path delays and residence time can occur when the PTP Instances involved in a particular measurement do not agree on the metric used in the measurements; that is, their Timestamping Clocks are not syntonized to the Grandmaster Clock of the domain. As an example. consider the peer-to- peer PTP Network of Figure 19.
In many implementations of Boundary Clocks and Ordinary Clocks, the Timestamping Clock is the Local PTP Clock that is synchronized by means of a servo loop, such that the measured offset of the Local PTP Clock, for example. of Boundary Clock BC-B, from the Local PTP Clock of the Grandmastcr PTP Instance is minimized. This technique does require careful design of the servo loop, for example, by controlling gain peaking and overshoot. In Figure 19, assume that the servo loops in BC-B and Ordinary Clock OC-D have resulted in the frequency of the Local PTP Clocks in these PTP Instances agreeing with that of the Grandmaster Clock by 0.1 ppm and 0.2 ppm. respectively.
Next consider the situation in peer-to-peer Transparent Clock TC-C. Here the measurement of the residence time of PTP event messages is based on the Timestamping Clock that is the Local Clock. The Local Clock is commonly free running and, in this example, differs from the frequency of the Local PTP Clock of the Grandmastcr PTP Instance by 100 ppm. If the residence time is about 10 ms, the measurement error introduced by the discrepancy in the frequencies is 10(X) ns (10 x 10 2 s = 10 6 s). This error would appear in the computation of the offset from master in OC-D.IEEE 1588-2019 pdf free download.
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