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Tones and Noise (Frequency Domain » Arbitrary Tones) (G Dataflow)

Last Modified: January 12, 2018

Generates a waveform that is the sum of integer cycle sine tones with arbitrary frequencies.

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coerce frequencies?

A Boolean that specifies whether to coerce the tone frequencies.

True Coerces the specific tone frequencies to the nearest multiple of fs/n.
False Does not coerce the specific tone frequencies to the nearest multiple of fs/n.

Default: False

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amplitude

Value that the sum of all the tones is scaled to and the largest absolute value that the waveform contains.

Default: -1

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reset

A Boolean that specifies whether to reset the phase to the initial phase value and the timestamp to 0.

True Resets the phase to the initial phase value and the timestamp to 0.
False Does not reset the phase to the initial phase value and the timestamp to 0.

Default: False

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tone amplitudes

An array in which each element is a single tone amplitude.

The size of this array must match the size of the tone frequencies array and the size of the tone phases array.

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tone frequencies

An array in which each element is a single tone frequency.

The size of this array must match the size of the tone amplitudes array and the size of the tone phases array.

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tone phases

An array in which each element is a single tone phase in degrees.

The size of this array must match the size of the tone frequencies array and the size of the tone amplitudes array.

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error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

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sample rate

Sampling rate in samples per second.

Default: 1000

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samples

Number of samples in the signal.

samples must be greater than 0. Otherwise, this node returns an error.

Default: 1000

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t0

Timestamp of the output signal. If this input is unwired, this node uses the current time as the timestamp of the output signal.

This input is available only if you configure this node to return a waveform.

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signal

Generated signal.

This output can return a waveform or an array of double-precision, floating-point numbers.

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crest factor

Ratio of the Peak voltage to the RMS voltage of the output signal.

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actual tone frequencies

Tone frequencies generated after accounting for coercion and the Nyquist criteria.

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error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Algorithm for Generating the Waveform Signal

The frequency domain representation of this waveform is a sequence of impulses at the specified tone frequencies and zero at all other frequencies. The number of tones is determined by the size of the input tone frequencies, tone amplitudes, and tone phases. This node generates the sine tones according to the following steps:

  1. Uses the frequency, phase, amplitude, and samples information with the inverse fast Fourier transform (FFT) to create a raw array.
  2. Scales the raw array so that the largest absolute value is equal to amplitude.
  3. Bundles the waveform. The t0 element of the waveform always is set equal to 0 and the dt element is set equal to 1/sample rate.

This node assumes tone phases to be referenced to the sine function. For example, if tone phases is n degrees, the phase of the output signal referenced to the sine function is also n degrees. To reference tone phases to the cosine function, add 90 degrees. Be aware that adjusting the reference function may change the crest factor.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application


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