fvtool

(To be removed) Visualize the filters in the channelizer

Syntax

fvtool(obj)

fvtool(obj,ind)

fvtool(obj,ind,Name,Value)

Description

fvtool(obj) visualizes the filters in the dsp.Channelizer System object™ using the Filter Visualization Tool (FVTool).

fvtool(obj,ind) visualizes the filters corresponding to the indices in the vector ind. ind is a row vector of indices between 1 and obj.NumFrequencyBands. By default, this vector is [1:N], where N is the smallest of obj.NumFrequencyBands and 64.

For example, to visualize the first 4 filters, set ind to [1:4].

channelizer = dsp.Channelizer;
fvtool(channelizer,[1:4]);

fvtool(obj,ind,Name,Value) visualizes the filters with additional options specified by one or more Name,Value pair arguments.

For example, to visualize the first 4 filters in the channelizer over the Nyquist interval [–44100/2, 44100/2] Hz, set 'Fs' to 44100. To compute the frequency response using 1024 frequency points, set 'NFFT' to 1024. In addition, to visualize sum of the filter responses, set 'overall' to true.

channelizer = dsp.Channelizer;
fvtool(channelizer,[1:4],'Fs',44100,'NFFT',1024,'overall',true);

Examples

Visualize Filters in Channelizer

Using the fvtool function, you can visualize the individual filter responses or sum of all the filter responses in the channelizer filter bank.

Design a channelizer with the number of frequency bands or polyphase branches set to 8, the number of taps or coefficients per band set to 12, and stopband attenuation set to 80 dB. View the response of the filter bank.

channelizer = dsp.Channelizer;
fvtool(channelizer)

The fvtool shows the response of the lowpass prototype filter and all the modulated filters. To view only a portion of the filter bank, specify the indices in ind. To view the response of the first 4 filters, set ind to [1:4].

fvtool(channelizer,(1:4));

You can change the Nyquist interval to [-22,050 22,050] Hz and the number of frequency points to 1024.

fvtool(channelizer,(1:4),'Fs',44100,'NFFT',1024);

To see the sum of the responses of all 4 filters, set the 'overall' argument to true.

fvtool(channelizer,(1:4),'Fs',44100,'NFFT',1024,'overall',true);

Input Arguments

obj — Input filter System object

dsp.Channelizer

Input filter, specified as a dsp.Channelizer System object.

Example: channelizer = dsp.Channelizer; fvtool(channelizer);

ind — Filter indices

row vector

Filter indices, specified as a row vector in the range [1 obj.NumFrequencyBands]. By default, ind is set to 1:N, where N is the smallest of obj.NumFrequencyBands and 64.

Example: fvtool(channelizer,[1:4]);

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: fvtool(channelizer,'Fs',44100,'NFFT',1024,'overall',true);

Fs — Sampling rate

scalar

Sampling rate, specified as a scalar. This value determines the Nyquist interval [-Fs/2 Fs/2] in which the fvtool shows the frequency response of the filters in the channelizer.

Example: 44100

Example: 22050

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

NFFT — Number of frequency points used to compute the frequency response

8192 (default) | positive scalar

Number of frequency points used to compute the frequency response, specified as a positive scalar.

Example: 8192

Example: 1024

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

overall — Type of filter response

false (default) | true

Type of filter response, specified as either:

• true –– fvtool shows the sum of the filter responses.

• false –– fvtool shows the individual filter responses.

Data Types: logical

Version History

Introduced in R2017b

R2024b: fvtool will be removed

The fvtool function will be removed in a future release. Use the freqz function instead.

Update Code

This table shows how to update existing code to use the freqz function.

Discouraged Usage

Recommended Replacement

Design a channelizer with the number of frequency bands or polyphase branches set to 8, the number of taps or coefficients per band set to 12, and stopband attenuation set to 80 dB. View the response of the filter bank. channelizer = dsp.Channelizer; Using the fvtool function, you can visualize the individual filter responses or sum of all the filter responses in the channelizer filter bank. Visualize the individual filter responses of all the filters. fvtool(channelizer) View the response of the first 4 filters. fvtool(channelizer,(1:4)); Change the Nyquist interval to [−22050 22050] Hz and the number of frequency points to 1024. fvtool(channelizer,(1:4),... Fs=44100,NFFT=1024); To see the sum of the responses of all 4 filters, set the 'overall' argument to true. fvtool(channelizer,(1:4),... Fs=44100,NFFT=1024,overall=true);

Visualize the individual filter responses of all the filters. freqz(channelizer) View the response of the first 4 filters. freqz(channelizer,(1:4)); Change the Nyquist interval to [−22050 22050] Hz and the number of frequency points to 1024. freqz(channelizer,(1:4),... Fs=44100,NFFT=1024); To see the sum of the responses of all 4 filters, set the 'overall' argument to true. freqz(channelizer,(1:4),... Fs=44100,NFFT=1024,overall=true);