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Performs a total harmonic distortion plus noise (THD+N) analysis, including measuring the fundamental tone, and returns the detected fundamental frequency, detected fundamental amplitude, and THD+N. Signal in noise and distortion (SINAD) is the negative of THD+N in dB. You can use this polymorphic VI to perform THD+N analysis on a scaled signal or a complex spectrum. The data type you wire to the scaled signal [EU] input determines the polymorphic instance to use.

Use the pull-down menu to select an instance of this VI.

Select an instance SVT THD+N (Time) (1 Ch)SVT THD+N (Frequency) (1 Ch)

SVT THD+N (Time) (1 Ch)

	desired units specifies the engineering units of the returned measurements. THD+N units specifies the units for THD+N. 0 dB (default) 1 Linear ratio 2 % detected fundamental amplitude units specifies the units for the amplitude of the detected fundamental tone. 0 EU rms (default) 1 EU peak 2 EU peak-peak
	scaled signal [EU] specifies the scaled signal expressed in the selected engineering units. To obtain a properly scaled signal, you can use the SVL Scale Voltage to EU VI or define a virtual channel in National Instruments Measurement & Automation Explorer (MAX).
	frequency range defines the frequency band of analysis. start frequency specifies the lowest frequency of interest for the analysis band in hertz. Specify a value of -1 to select f0 as the minimum frequency of interest. stop frequency specifies the highest frequency of interest for the analysis band in hertz. The valid range is between 0 and the Nyquist frequency. Specify a value of –1 to select the highest frequency as the maximum frequency of interest.
	advanced span [Hz] specifies a frequency span centered at the identified fundamental frequency in which noise and spurious components are ignored for the measurement. Specify a value of -1 to permit the measurement to automatically compute the minimum frequency span suitable for the time-domain window applied to the signal.
	error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Refer to Controlling Error Notification to treat what is normally an error as no error or to treat a warning as an error. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node. status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE. code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
	expected fundamental frequency specifies the expected frequency of the fundamental tone in hertz. Use expected fundamental frequency when the fundamental tone is not the largest amplitude component of the input signal.
	unit labels returns the unit label for each member of desired units. THD+N unit label returns the unit label for THD+N. detected fundamental amplitude unit label returns the unit label for the amplitude of the detected fundamental tone.
	complex spectrum returns the complex form of the computed spectrum. complex spectrum returns the complex form of the spectrum. f0 returns the start frequency, in hertz, of the spectrum. df returns the frequency resolution, in hertz, of the spectrum. complex spectrum returns the complex form of the computed spectrum. spectrum info returns information about the spectrum needed by the Spectrum Extended Measurements VIs, the Waterfall Display VIs, the Distortion VIs, and the Single Tone Measurements VIs. Do not modify the spectrum info values.
	THD+N returns the measured total harmonic distortion plus noise (THD+N), which is defined as the ratio of the RMS energy of the input signal less the RMS energy of the fundamental tone to the RMS energy of the input signal.
	error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error. status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred. code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.
	detected fundamental amplitude returns the amplitude of the detected fundamental tone.
	detected fundamental frequency [Hz] returns the frequency of the detected fundamental tone in hertz.

SVT THD+N (Frequency) (1 Ch)

	desired units specifies the engineering units of the returned measurements. THD+N units specifies the units for THD+N. 0 dB (default) 1 Linear ratio 2 % detected fundamental amplitude units specifies the units for the amplitude of the detected fundamental tone. 0 EU rms (default) 1 EU peak 2 EU peak-peak
	complex spectrum is the complex form of the computed spectrum. complex spectrum response is the complex form of the spectrum for the response channel. f0 specifies the start frequency, in hertz, of the spectrum. df specifies the frequency resolution, in hertz, of the spectrum. complex spectrum is the complex form of the computed spectrum. spectrum info contains information about the spectrum needed by the Spectrum Extended Measurements VIs, the Waterfall Display VIs, the Distortion VIs, and the Single Tone Measurements VIs. Do not modify the spectrum info values.
	frequency range defines the frequency band of analysis. start frequency specifies the lowest frequency of interest for the analysis band in hertz. Specify a value of -1 to select f0 as the minimum frequency of interest. stop frequency specifies the highest frequency of interest for the analysis band in hertz. The valid range is between 0 and the Nyquist frequency. Specify a value of –1 to select the highest frequency as the maximum frequency of interest.
	advanced span [Hz] specifies a frequency span centered at the identified fundamental frequency in which noise and spurious components are ignored for the measurement. Specify a value of -1 to permit the measurement to automatically compute the minimum frequency span suitable for the time-domain window applied to the signal.
	error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Refer to Controlling Error Notification to treat what is normally an error as no error or to treat a warning as an error. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node. status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE. code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
	expected fundamental frequency specifies the expected frequency of the fundamental tone in hertz. Use expected fundamental frequency when the fundamental tone is not the largest amplitude component of the input signal.
	unit labels returns the unit label for each member of desired units. THD+N unit label returns the unit label for THD+N. detected fundamental amplitude unit label returns the unit label for the amplitude of the detected fundamental tone.
	dup complex spectrum returns complex spectrum unchanged. complex spectrum returns the complex form of the spectrum. f0 returns the start frequency, in hertz, of the spectrum. df returns the frequency resolution, in hertz, of the spectrum. complex spectrum returns the complex form of the computed spectrum. spectrum info returns information about the spectrum needed by the Spectrum Extended Measurements VIs, the Waterfall Display VIs, the Distortion VIs, and the Single Tone Measurements VIs. Do not modify the spectrum info values.
	THD+N returns the measured total harmonic distortion plus noise (THD+N), which is defined as the ratio of the RMS energy of the input signal less the RMS energy of the fundamental tone to the RMS energy of the input signal.
	error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error. status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred. code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.
	detected fundamental amplitude returns the amplitude of the detected fundamental tone.
	detected fundamental frequency [Hz] returns the frequency of the detected fundamental tone in hertz.