Continuous Pulse Output Jitter on TIO Devices Hardware: Counter/Timers (TIO)>>Devices>>PCI-6602, Counter/Timers (TIO)>>Devices>>PXI-6608, Counter/Timers (TIO)>>Devices>>PXI-6624, Counter/Timers (TIO)>>Devices>>PCI-6608, Counter/Timers (TIO)>>Devices>>PXI-6601, Counter/Timers (TIO)>>Devices>>PCI-6601, Counter/Timers (TIO)>>Devices>>PXI-6602, Counter/Timers (TIO)>>Devices>>PCI-6624
Problem: There is no jitter specification on pulse train output for these devices:
Solution: Because the counter/timer chip can generate many types of output, a more generic specification is given. The Baseclock Accuracy specifies how many pulses of the reference clock are generated correctly, usually as a measure of parts per billion (ppb). Since all counter outputs are ultimately derived from this clock, it can be used to determine the worst-case frequency shift of the output. For example, a PXI-6608 wil use the OCXO signal as its reference, which has an accuracy of 75 ppb. This equates to roughly +/- 0.75 Hz deviation from 10 MHz. So if you're generating a 1 kHz clock, this makes 10,000 pulses of the reference for every period of the output. If the reference is operating between 9,999,999.25 Hz and 10,000,000.75 Hz, then the 10,000 pulses of this clock will have a length of 0.999,999,925 ms to 1.000,000,075 ms. This translates to an output frequency range of 999.999925 Hz to 1000.000075 Hz, or a jitter of +/- 0.000,007,5%. Related Links: TIO Series Help (User Manual and Specifications) NI PXI-660x Specifications Attachments:
Report Date: 04/20/2007 Last Updated: 04/24/2007 Document ID: 48JB1VD3 |
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