Phase VI

Owning Palette: Timing VIs

Requires: Jitter Analysis Toolkit

Measures the differences in phase between corresponding cycles in two waveforms.

You can use this VI to measure the response of a signal to a particular stimulus. For example, level crossings A might be the original signal, and level crossings B might be the response signal following a stimulus. You also can use this VI to compare waveforms from two different channels.

Details  

	level crossings A contains information about the locations of level crossings in a waveform. You can use the Level Crossing VI to generate this cluster from a waveform. t0 specifies the time at which the first sample occurs in the original waveform. dt specifies the time interval in seconds between the individual samples in the original waveform. indexes contains the index numbers of the samples in the waveform with values that fall at the crossing level. slope identifies the direction of the first transition in the waveform. -1 Falling Edge—Specifies the transition is a falling edge, or one with a negative slope. 1 Rising Edge (default)—Specifies the transition is a rising edge, or one with a positive slope. crossing level specifies the value of the waveform at each of the samples in indexes.
	level crossings B (ref) contains information about the locations of level crossings in a waveform. level crossings B (ref) serves as the reference against which this VI compares level crossings A. You can use the Level Crossing VI to generate this cluster from a waveform. t0 specifies the time at which the first sample occurs in the original waveform. dt specifies the time interval in seconds between the individual samples in the original waveform. indexes contains the index numbers of the samples in the waveform with values that fall at the crossing level. slope identifies the direction of the first transition in the waveform. -1 Falling Edge—Specifies the transition is a falling edge, or one with a negative slope. 1 Rising Edge (default)—Specifies the transition is a rising edge, or one with a positive slope. crossing level specifies the value of the waveform at each of the samples in indexes.
	phase unit specifies the units in which to express the phase measurements. 0 degrees (default) 1 radians
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	rising/falling specifies the direction of the transition at which to begin the measurement. This VI begins measuring at the first transition of that direction in the waveform. –1 Falling Edge—Specifies to begin measuring at the first falling edge in the waveform. 1 Rising Edge (default)—Specifies to begin measuring at the first rising edge in the waveform.
	phase sequence returns the differences between the times that cycles begin, in units specified by phase unit. The time difference relative to the period of level crossings A (Tdiff/T) is the phase ratio.
	phase timestamps returns timing information about the waveform that allows you to identify the times at which measurements in the corresponding sequence occurred. t0 returns the time at which the first sample occurred in the original waveform. dt returns the time interval in seconds between the individual samples in the original waveform. indexes contains the index numbers of all waveform samples that fall on the crossing level in transitions of the direction you specify in slope. This VI returns the index numbers from level crossings A.
	mean phase is the average of the phase offset measurements returned in phase sequence. This VI uses the Mean VI to compute the mean of the values in phase sequence.
	error out contains error information. This output provides standard error out functionality.

Phase Details

This VI uses level crossings B (ref) as the reference against which to measure the phase difference in level crossings A. Thus, when level crossings A occurs after level crossings B (ref), the phase measurement is positive. When the opposite is true, the phase measurement is negative.

To identify the first pair of cycles to measure, this VI finds the edge in level crossings B nearest to the first edge in level crossings A of the direction specified by slope. The next edges of the same direction in each input also become pairs, and so on.