Synchronization Frequency for PXI-6682 and PCI-1588 Implementing PTP Hardware: Instrument Connectivity Other>>IEEE 1588>>PCI-1588
Problem: Both the PXI-6682 and PCI-1588 support PTP (Precision Time Protocol) but they each have a different synchronization frequency. Why is there such a large difference in the accuracy and what is this accuracy measurement dependent on? Solution: The datasheet states that the synchronization frequencies are as follows: PCI-1588 :- 230ns PXI- 6682:- 47ns The reason for the difference in values is that the PXI-6682 has a more stable TCXO oscillator that specs out at 1 ppm versus the PCI-1588 which has a 1.5 ppm TCXO. In addition to this, the PXI-6682 has a faster and more powerful FPGA that has the ability to timestamp 1588 packets with about 5 ns of resolution compared to the PCI-1588 which only has 16 ns of resolution. The finer resolution allows us to make finer clock adjustments and therefore reduce the jitter in the synchronization. The hardware performs all of the timestamping, while the software handles the servo algorithms to adjust the clocks. Related Links: Developer Zone Tutorial: Introduction to Distributed Clock Synchronization and the IEEE 1588 Precision Time Protocol Products & Services: NI PXI-6682 Products & Services: NI PCI-1588 Interface Attachments:
Report Date: 02/14/2008 Last Updated: 03/25/2008 Document ID: 4IDLTCDH |
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