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Buneman Frequency Estimator (G Dataflow)

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Last Modified: January 12, 2018

Estimates the frequency of a given sine wave of unknown frequency using the Buneman algorithm.

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reset

A Boolean that specifies whether to reset the internal state of the node.

True Resets the internal state of the node.
False Does not reset the internal state of the node.

This input is available only if you wire a double-precision, floating-point number to x.

Default: False

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x

The sampled signal at consecutive times.

This input accepts the following data types:

  • Waveform
  • Double-precision, floating-point number
  • 1D array of double-precision, floating-point numbers
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sample length

Length of each set of data. The node performs computation for each set of data.

sample length must be greater than zero.

This input is available only if you wire a double-precision, floating-point number to x.

Default: 100

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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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beta

The frequency estimation of the sine wave that the sampled signal represents. This output is the index of the maximum frequency and a noninteger.

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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.

Using the Buneman Algorithm to Calculate the Frequency

If an underlying time signal is not exactly periodic with period n, where n denotes the size of the data array, you can use the Buneman algorithm to calculate the unknown frequency 0 ≤ f0 ≤ f1 ≤ f2 ≤ f3 < 0.5fs.

The following formula describes the Buneman algorithm:

β = b + n π a ⁢ tan ⁡ ( ( sin ⁡ π n ) cos ⁡ π n + | F b ( x ) | | F b + 1 ( x ) | )

where b is the frequency and Fb is the value of the Fourier transform of the input signal X at b. You can determine the value of b using the greatest value of | F b ( X ) | .

The formula for β is exact for pure sine waves and a good estimation in all other cases.

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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