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Generates a set of linear-phase FIR multiband digital filter coefficients.

## number of taps

The total number of coefficients in h.A tap corresponds to a multiplication and an addition. If there are n taps, every filtered sample requires n multiplications and n additions.

This input must be greater than 2. If it is less than or equal to 2, the node returns an error as well as an empty array for h and NaN for ripple.

Default: 32

## sampling frequency

Is the sampling frequency in Hz.

If this input is less than or equal to zero, the node returns an empty array for h as well as an error.

Default: 1.0 Hz

## band parameters

An array of clusters in which each cluster contains the necessary information associated with each band for the FIR design.

If this array does not contain any elements, the node returns an error as well as an empty array for h and NaN for ripple.

### Amplitude

The appropriate magnitude response, or gain, of the filter between Lower Freq and Higher Freq. A value of 1.0 corresponds to a passband, and a value of 0.0 corresponds to a stopband. If you set filter type to Differentiator, the Amplitude of a band is the slope of the frequency response in that band.

### Lower Freq

The frequency at which the band begins.

### Higher Freq

The frequency at which the band ends.

### Weighted Ripple

The weighted ripple error that this node minimizes. The higher the weight, the smaller the error in the band. For each band, Higher Freq must be greater than Lower Freq, as shown by the following relationship.

${f}_{{h}_{i}}>{f}_{{l}_{i}}$
for
$i=0,1,2,...,m-1$

where ${f}_{{h}_{i}}$ is the Higher Freq in the ith band, ${f}_{{l}_{i}}$ is the Lower Freq in the ith band, and m is the number of bands.

For adjacent bands, the Lower Freq in the higher band must be greater than the Higher Freq in the adjacent lower band, as shown by the following relationship:

${f}_{{l}_{i}}>{f}_{{h}_{i-1}}$
for
$i=0,1,2,...,m-1$

where ${f}_{{l}_{i}}$ is the Lower Freq in the higher of the adjacent bands, ${f}_{{h}_{i-1}}$is the Higher Freq in the lower of the adjacent bands, and m is the number of bands.

The Higher Freq in the last band must be equal to or less than half of sampling frequency.

If any of the preceding frequency conditions are violated, the node returns an error as well as an empty array for h and NaN for ripple.

Default: Empty array

## filter type

The type of filter that you want to use.

 Multiband Uses a multiband filter. If number of taps is an odd number, this node does not place restrictions on the value of the Amplitude. If number of taps is an even number, the Amplitude of the last band at half of sampling frequency must be 0. Differentiator Uses a differentiator. If number of taps is an even number, this node does not place restrictions on the last band. If number of taps is an odd number, the value of Higher Freq in the last band must be less than half of sampling frequency. For example, a typical normalized band {0, 0.49} leaves a 0.01 transitional band at half of the sampling frequency, 0.5. Hilbert Uses a Hilbert transformer. The value of Lower Freq in the first band must be greater than 0. A typical normalized Lower Freq in the first band is 0.03. If number of taps is an even number, this node does not place restrictions on the last band. If number of taps is an odd number, the value of Higher Freq in the last band must be less than half of sampling frequency. A typical normalized Higher Freq in the last band is 0.49.

Default: Multiband

## h

An array of FIR filter coefficients, which the node computes using the Parks-McClellan algorithm with the Remes exchange technique.

## ripple

The optimal ripple the node computes and is a measure of deviation from the ideal filter specifications.

## error

A value that represents any error or warning that occurs when this node executes.