DSP Blockset

Analytic Signal

Compute the analytic signal of a discrete-time input

Library

Transforms

Description

The Analytic Signal block computes the complex analytic signal corresponding to each channel of the real M-by-N input, u

where and H{ } denotes the Hilbert transform. The real part of the output in each channel is a replica of the real input in that channel; the imaginary part is the Hilbert transform of the input. In the frequency domain, the analytic signal retains the positive frequency content of the original signal while zeroing-out negative frequencies and doubling the DC component.

The block computes the Hilbert transform using an equiripple FIR filter with the order specified by the Filter order parameter, n. The linear phase filter is designed using the Remez exchange algorithm, and imposes a delay of n/2 on the input samples.

The output has the same dimension and frame status as the input.

Sample-Based Operation

When the input is sample based, each of the M*N matrix elements represents an independent channel. Thus, the block computes the analytic signal for each channel (matrix element) over time.

Frame-Based Operation

When the input is frame based, each of the N columns in the matrix contains M sequential time samples from an independent channel, and the block computes the analytic signal for each channel over time.

Dialog Box

Filter order

The length of the FIR filter used to compute the Hilbert transform.

Supported Data Types

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

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

Analog Filter Design

Autocorrelation