Align and Resample

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Updated2025-03-14
5 minute(s) read

Align and Resample

Performs an alignment of signals by changing the start time or performs a resampling of signals by changing the time delta. This Express VI returns the adjusted signals.

Dialog Box Options


Option	Description
Acquisition Type	Contains the following options: Single segment— Aligns and/or resamples each iteration separately. Continuous— Aligns and/or resamples all iterations as one continuous segment.
Align	Aligns the signals to have the same start time.
Alignment Interval	Contains the following options: Global— Aligns the start and end times of signals by adding zero values to the beginning of the signal that starts last and to the end of the signal that ends first. Common— Aligns the start and end times of signals by using the start time of the signal that starts last and the end time of the signal that ends first.
Resample	Resamples the signals to have the same sampling interval.
Resampling Interval	Contains the following options: Lowest dt— Resamples all the signals to have the same sampling interval as the signal with the smallest sampling interval. Specific dt— Resamples all the signals to have a user-defined sampling interval. dt— Sampling interval you define. The default is 1. Reference signal— Resamples all the signals to have the same sampling interval as a reference signal.
Interpolation Mode	When resampling, you might need to add points to the signal. Interpolation Mode controls how LabVIEW calculates the amplitude of the new points. Interpolation Mode contains the following options: Linear— Returns an output sample value equal to a linear interpolation between the two input samples that are closest to the output sample value in time. Coerce— Returns an output sample value equal to the input sample value that is closest to the output sample value in time. Spline— Uses the spline interpolation algorithm to compute the resampled values. FIR filter— Uses an FIR filter to compute the resampled values.
FIR Filter Parameters	Contains the following options: Alias rejection (dB)— Specifies the minimum attenuation level of signal components aliased after any resampling operation. The default is 120. This option is available only when you select FIR filter. Normalized bandwidth— Specifies the fraction of the new sampling rate that is not attenuated. The default is 0.4536. This option is available only when you select FIR filter.
Open interval	Defines whether an input signal is an open or closed interval. The default is TRUE, which selects an open interval. For example, assume an input signal has t0 = 0, dt = 1, and Y = {0, 1, 2}. An open interval returns a final time value of 2. A closed interval returns a final time value of 3.
Sample Input Data	Displays sample input signals you can use as a reference to determine how the configuration options you select affect the actual input signals. If you wire data to the Express VI and run it, Sample Input Data displays real data. If you close and reopen the Express VI, Sample Input Data displays sample data until you run the VI again.
Result Preview	Displays a preview of the measurement. The Result Preview plot indicates the value of the selected measurement with a dotted line. If you wire data to the Express VI and run the VI, Result Preview displays real data. If you close and reopen the Express VI, Result Preview displays sample data until you run the VI again. If the cutoff frequency values are invalid, Result Preview does not display valid data.

Inputs/Outputs

error in (no error) —

Describes error conditions that occur before this node runs.

Reset —

Controls the initialization of the internal state of the VI. The default is FALSE.

Signals 2 —

Contains the input signal(s).

Signals —

Contains the input signal or signals.

Reference Signal —

Contains a reference signal whose sampling interval is used as the rate at which this Express VI resamples the input signals. If you wire a value to this input, the wired value overrides the value you set in the configuration dialog box.

dt —

Specifies a sampling interval you define. If you wire a value to this input, the wired value overrides the value you set in the configuration dialog box.