Arithmetic (Time Domain)

LabVIEW SignalExpress

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Arithmetic (Time Domain)

Performs arithmetic operations on two signals. The available operations change depending on the type of the input signals you select.

To select the correct type of operation, select the first signal to process from the Input signal 1 pull-down menu. The Input signal 2 pull-down menu displays only the list of compatible signals, and the step displays the available operations.

Parameter

Description

Input Signals

Displays the two input signals.

Displayed signal—Specifies the signal(s) to display in the preview graph(s). This option appears only when you select a group of signals for the input.
Note If the input signals include scalar values that depend on the values of input waveform signals, you cannot specify to display all signals in the preview graph(s).

Resulting Signal

Displays the signal that results from the arithmetic operation.

Input

Contains the following options:

Input signal 1—Specifies the first input signal.
Input signal 2—Specifies the second input signal.

Configuration

Contains the following option:

Operation Setup—Contains the following options:
- Operation—Specifies to add, subtract, multiply, or divide the signals or compute the RMS sum of the signals. The default is to add the signals.
- Ignore timestamp—Ignores eventual differences in timestamps by forcing the second signal timestamp to be equal to the first signal timestamp.
- Interpolate if needed—Resamples the signals to align the samples.
- Optimized for single record—Optimizes the resampling operation for executing Arithmetic once. Place a checkmark in this checkbox to speed execution when Arithmetic runs once.
- Interpolation type—Contains the following options:
  - Coerce—Sets each output sample value to equal the input sample value that is closest to it in time.
  - Linear—Sets each output sample value to be a linear interpolation between the two input samples that are closest to it in time.
  - Spline—Uses the spline interpolation algorithm to compute the resampled values.
  - Filter based—Uses an interpolation method based on the convolution of the signal with a finite impulse response (FIR) filter.
- Resulting interval—Specifies if the resulting signal covers the Common or Global time interval of the signals.

Filter Setup

Available when you select Filter based from Interpolation type. Contains the following option:

FIR Filter Specification—Contains the following options:
- Normalized bandwidth—The normalized cut-off frequency of the FIR filter to use. The default is 0.4000.
- Alias rejection (dB)—The minimum stopband attenuation of the FIR filter to use. The default is 80 dB.

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