Discrete Transfer Function Estimator With Magnitude
Calculation of the estimate of the transfer function in the frequency domain.
blockType: DiscreteTransferFunctionEstimatorWithMagnitude
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Path in the library: |
Description
Block Discrete Transfer Function Estimator With Magnitude evaluates the transfer function of the system in the frequency domain using the method of averaged modified Welch periodograms.
The block splits the input data into overlapping segments. The length of the data segment and the amount of data overlap can be set using the block parameters. The sampling frequency of the block is equal to , where — the sampling interval of the input signals of the block.
First, the block applies a window function to two input signals and , and then scales them by the power of the window. The block performs a fast Fourier Transform (FFT) for each signal, naming them and . The block calculates — square FFT . Then the block calculates — the work and the conjugate value . Estimation of the output transfer function calculated by dividing on .
Ports
Input
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IN_1
—
Input signal
vector | the matrix
Details
An input signal specified as a vector or matrix.
Input signals and must have the same size and data type.
| Data types |
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| Complex numbers support |
I don’t |
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IN_2
—
Input signal
vector | the matrix
Details
An input signal specified as a vector or matrix.
Input signals and must have the same size and data type.
| Data types |
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| Complex numbers support |
I don’t |
Output
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OUT_1
—
evaluation of the transfer function
vector | the matrix
Details
The estimate of the transfer function returned as a vector or matrix. For more information on how the block calculates the estimate of the transfer function, see Algorithms.
| Data types |
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| Complex numbers support |
I don’t |
Parameters
Main
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Window length source —
the source of the window length
Same as input frame length
Details
The source of the window length value.
| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
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Window overlap (%) —
overlapping the window, %
Int64 integer
Details
The percentage of overlap between consecutive data windows, set as a scalar in the range [0,100).
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
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Averaging method —
the averaging method
Running
Details
Set the averaging method. In the current implementation, only the method is available Running — the block calculates an equally weighted average value of the number of estimates of the spectrum specified by the parameter Number of spectral averages.
| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
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Number of spectral averages —
number of spectral averages
Int64 integer
Details
Set the number of spectral averages. Block Discrete Transfer Function Estimator With Magnitude calculates the current score by averaging the latest estimates where — the number of spectral averages. It can be any positive integer scalar.
Dependencies
To use this parameter, set for the parameter Averaging method meaning Running.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
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FFT length source —
the source of the FFT length
Property
Details
By default, the length of the FFT is determined by the parameter FFT length.
| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
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FFT length —
FFT length
Int64 integer
Details
Set the length of the FFT that the block Discrete Transfer Function Estimator With Magnitude It is used to calculate spectral estimates. It can be any positive integer scalar.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
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Window function —
window function
Hann
Details
Set the window function for the block Discrete Transfer Function Estimator With Magnitude.
| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
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Frequency range —
frequency range
One-sided
Details
Set the frequency range for estimating the transfer function.
Meaning One-sided means that the block Discrete Transfer Function Estimator With Magnitude calculates a one-way transfer function of real input signals and .
| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
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Output magnitude squired coherence estimate —
estimation of the square of the output coherence value
Logical
Details
Select this option to calculate and output an estimate of the coherence square using the averaged modified Welch periodogram method. The coherence square score shows how well the two input signals match each other at each frequency.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
Algorithms
The method of averaged modified Welch periodograms
Details
For two input signals and The block performs the following steps:
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Multiplies the input signals by the window function and scales the result by the power of the window.
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Performs FFT of signals and and gets the values and .
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Calculates current power spectral density estimates , and the current cross-estimation of the power spectral density taking the moving average of the last elements of vectors , and accordingly:
The estimate of the transfer function is calculated by dividing on .
The square of the coupling coefficient defined as: