DSP Blockset

Convolution

Compute the convolution of two inputs.

Library

Signal Operations

Description

The Convolution block convolves corresponding columns (channels) of an M_u-by-N input matrix u and an M_v-by-N input matrix v. The block does not accept sample-based full-dimension matrix inputs, and the outputs are always sample-based.

Sections of This Reference Page

• Convolving Frame-Based Inputs
• Convolving Sample-Based Inputs
• Setting the Computation Domain Parameter
• Dialog Box
• Supported Data Types
• See Also

Convolving Frame-Based Inputs

Matrix inputs must be frame-based. The output, y, is a frame-based (M_u+M_v-1)-by-N matrix whose jth column has elements

where * denotes the complex conjugate. Inputs u and v are zero when indexed outside of their valid ranges. When both inputs are real, the output is real; when one or both inputs are complex, the output is complex.

When one input is a column vector (single channel) and the other is a matrix (multiple channels), the single-channel input is independently convolved with each channel of the multichannel input. For example, if u is a M_u-by-1 column vector and v is an M_v-by-N matrix, the output is an (M_u+M_v-1)-by-N matrix whose jth column has elements

Convolving Sample-Based Inputs

If u and v are sample-based vectors with lengths M_u and M_v, the Convolution block performs the vector convolution

The dimensions of the sample-based output vector are determined by the dimensions of the input vectors:

• When both inputs are row vectors, or when one input is a row vector and the other is a 1-D vector, the output is a 1-by-(M_u+M_v-1) row vector.
• When both inputs are column vectors, or when one input is a column vector and the other is a 1-D vector, the output is a (M_u+M_v-1)-by-1 column vector.
• When both inputs are 1-D vectors, the output is a 1-D vector of length M_u+M_v-1.

The Convolution block does not accept sample-based full-dimension matrix inputs, or mixed sample-based row vector and column vector inputs.

Setting the Computation Domain Parameter

You must set the domain in which the block computes convolutions in the Computation domain parameter. You can select one of the following settings:

• Time -- The block computes in the time domain, which minimizes memory use.
• Frequency -- The block computes in the frequency domain, which may require fewer computations than computing in the time domain (depending on the input length).
• Fastest -- The block computes in the domain that minimizes the number of computations (time domain or frequency domain).

Dialog Box

Computation domain

The domain in which the block computes convolutions: Time, Frequency, or Fastest. To minimize memory use, select Time. To minimize the number of computations, select Fastest. For more information, see Setting the Computation Domain Parameter

Supported Data Types

• Double-precision floating point
• Single-precision floating point

To learn how to convert to the above data types in MATLAB and Simulink, see Supported Data Types and How to Convert to Them.

See Also

Correlation	DSP Blockset
conv	MATLAB

Also see Signal Operations for a list of all the blocks in the Signal Operations library.

Convert 2-D to 1-D

Correlation