LabVIEW Analysis -- Express VIsLabVIEW includes configuration-based Express VIs for measurement analysis and signal processing. With Express VIs, you can interactively explore the various analysis algorithms, while immediately seeing the results on the configuration dialog. The complexity associated with adding analysis and signal processing algorithms into your measurement and automation applications is significantly reduced by using Express VIs. The Express VIs encompass the most common functions out of the more than 400 analysis and signal processing functions that LabVIEW offers.
This Express VI also includes windowing algorithms (e.g. Hanning, Hamming, Blackman), averaging, weighting, and phase unwrapping capabilities. The Distortion Measurements Express VI performs distortion measurements on a signal, such as Signal-to-Noise-And-Distortion ratio (SINAD), total harmonic distortion (THD), specific harmonic level, and custom frequency searching capabilities. The Tone Measurements Express VI performs single-tone measurements, such as amplitude, frequency, and phase. It can also search for a specific tone within a user-specified frequency range. The Amplitude and Level Measurements Express VI performs level measurements such as DC, RMS, maximum and minimum peak, peak-to-peak calculations, cycle average, and cycle RMS. The Timing and Transition Measurements Express VI performs measurements such as frequency, period, pulse duration, duty cycle, preshoot and overshoot percentage, and slew rate. The Curve Fitting Express VI performs model-based curve fitting based on the following types:
The Filter Express VI provides tools to configure such digital filters as lowpass, highpass, bandpass, and bandstop. The configuration dialog provides controls to interactively configure filter settings such as high and low cutoff frequencies, number of taps for finite impulse response (FIR) filters, topology selection for infinite impulse response (IIR) filters (Butterworth, Chebyshev, Inverse Chebyshev, Elliptic, and Bessel), and order selection. The Statistics Express VI performs the following statistical calculations:
The Convolution and Correlation Express VI performs signal processing algorithms such as convolution, deconvolution, auto correlation, and cross correlation. The Simulate Signal Express VI can generate signals of the following types:
When you generate a signal, you can specify the frequency, phase, amplitude, offset, samples per second, number of samples, and number of cycles. For noise, you can select from a variety of noise types. Examples of the noise types that you can add: uniform white noise, Gaussian white noise, periodic random noise, Gamma noise, Poisson noise, binomial noise, Bernoulli noise, MLS sequence, and inverse F noise. Amplitude, seed, and exponent are among the parameters you can set for noise. With the Mask and Limit Express VI, you can define limit masks to specify the upper and lower limits for your test signals. You can interactively define masks, and save or load them to disk. With the Histogram Express VI, you can specify number of bins, maximum and minimum value, as well as percent of total and sample count for amplitude representation. The Align and Resample Express VI, available under the Signal Manipulation palette, takes two or more signals and provides tools to align and resample the signals resulting from an acquisition with different sampling rates and acquisition parameters. This VI provides tools to select the acquisition type (single segment or continuous), alignment interval, and resampling characteristics (lowest dt, user-defined dt, or based on a reference signal). Interpolation modes include:
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