SINAD Analyzer N Chan VI

Takes a signal in and performs a full Signal in Noise and Distortion (SINAD) analysis, including measuring the fundamental frequency tone and returning the fundamental frequency and SINAD level in dB. Wire data to the signal in input to determine the polymorphic instance to use or manually select the instance.

Note

The multichannel waveform array input should be the result of a multichannel acquisition where each element of the array of waveforms is a distinct and separate channel of data.


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Inputs/Outputs

  • c1dmsdt.png signals in —

    signals in is the array of input time-domain signals.

  • cenum.png export mode —

    export mode selects the source of the signal and spectrum to export to exported signals.

    0none—Fastest computation
    1input signal—Input signal only
    2detected signal—Single tone
    3residual signal—Signal minus tone
  • cerrcodeclst.png error in (no error) —

    error in describes error conditions that occur before this node runs. This input provides standard error in functionality.

  • cnclst.png advanced search —

    advanced search controls the frequency domain search area, which is the center frequency and width, used for finding the fundamental frequency tone of the signal.

  • cdbl.png approx freq. (optional) —

    approx freq. is the center frequency used in the frequency domain search for the fundamental tone frequency. If set to the default value of –1.0, the tone with the highest amplitude is used as the fundamental tone.

  • cdbl.png search (+/- % of Fsampl.) —

    search is the frequency width, as a percentage of the sampling rate, for the frequency domain search for the fundamental tone frequency.

  • i1dcclst.png exported signals —

    exported signals is an array of exported signals.

  • imsdt.png exported time signal —

    exported time signal is the waveform containing the exported time signal as selected by export mode.

  • icclst.png exported spectrum (dB) —

    exported spectrum (dB) is the spectrum of the exported time signal as selected by export mode.

  • idbl.png f0 —

    f0 returns the start frequency, in hertz, of the spectrum.

  • idbl.png df —

    df returns the frequency resolution, in hertz, of the spectrum.

  • i1ddbl.png dB Spectrum (Hann) —

    dB Spectrum (Hann) is the magnitude spectrum of the (Hanning) windowed input signal, expressed in dB relative to 1.0 Vrms^2 for input signals in units of volts (V).

  • i1ddbl.png detected fundamental frequencies —

    detected fundamental frequencies is an array containing the detected fundamental frequency resulting from searching the frequency domain for each waveform.

  • i1ddbl.png SINAD (dB) —

    SINAD is an array containing the measured Signal in Noise and Distortion (SINAD) for each waveform expressed in dB. SINAD is defined as the ratio of the RMS energy of the input signal to the RMS energy of the input signal less the energy in the fundamental. To compute the THD Plus Noise in dB, simply negate the SINAD in dB.

  • i1ddbl.png THD Plus Noise —

    THD Plus Noise is an array containing the measured total harmonic distortion plus noise for each waveform.

  • ierrcodeclst.png error out —

    error out contains error information. This output provides standard error out functionality.

  • i1dcclst.png measurements info —

    measurements info is an array that returns information about your measurement, mainly warnings for inconsistencies in your input signal.

  • idbl.png uncertainty —

    uncertainty is reserved for future use.

  • ibool.png Warning —

    Warning is TRUE if a warning is generated during processing.

  • istr.png comments —

    comments contains a warning message when Warning is TRUE.

    • This VI is designed to process a single channel or multiple channels continuously, typically from within a For Loop or a While Loop.

    THD Plus Noise in dB is the negative of the SINAD in dB.

    Examples

    Refer to the following example files included with LabVIEW.

    • labview\examples\Signal Processing\Waveform Measurements\SINAD Measurement.vi