User manual

Chapter 3 Software Overview
NI-DAQ User Manual for PC Compatibles 3-98 ni.com
Figure 3-38. IRIG-B Transmission Frame
Clock Accuracy
Clock accuracy depends on the resolution of the clock source and the
accuracy of the synchronization pulse. The source of your IRIG-B stream
determines the accuracy of the synchronization pulse. You can calculate
the clock accuracy by adding the resolution of the clock source and the
accuracy of the synchronization pulse, both in nanoseconds. For example,
if you have a 50ns resolution and a 100ns synchronization pulse accuracy,
your clock accuracy is as follows:
Example Clock in a Measurement System
The block diagram in Figure 3-39 illustrates a system in which all the clock
capabilities of the TIO can be exploited. The chassis has its TIO board,
6602, synchronized to a GPS, but the other modules are not clock-capable.
Each of the other modules is programmed to assert a PXI trigger when it
receives an event. The TIO board is set up to time stamp the triggers of the
other modules as well as to save the clock value on the first time stamp.
With the system configured, you can determine the precise relationship
of all triggers throughout the system to correlate the data. If you clone
the system, you can correlate all the data from the individual systems
as a whole.
50ns 100ns+150ns=