tfestimate

Syntax

tfe=tfestimate(x,y)

tfe=tfestimate(x,y,window)

tfe=tfestimate(x,y,window,overlap)

tfe=tfestimate(x,y,window,overlap,nfft)

tfe=tfestimate(x,y,window,overlap,nfft,fs)

tfe=tfestimate(x,y,window,overlap,nfft,fs,range)

tfe=tfestimate(x,y,window,overlap,nfft,fs,range,'Estimator',est)

[tfe,freq]=tfestimate(...)

Inputs

x

The signal.

Type: double

Dimension: vector

window

The window size, or the window vector.

Type: double | integer

Dimension: scalar | vector

overlap

The number of overlapping points in adjacent windows.

Type: integer

Dimension: scalar

nfft

The size of the fft.

Type: integer

Dimension: scalar

fs

The sampling frequency.

Type: double

Dimension: scalar

range

The spectrum type: 'onesided' or 'twosided'.

Type: string

est

The estimator type, 'H1', 'H2' or 'H3'.

Type: string

'est'

The transfer function estimator.

The available options are:

'H1' (default)

cpsd(x,y) ./ psd(x).

'H2'

psd(y) ./ cpsd(y, x).

'H3'

sqrt(psd(y) ./ psd(x)) .* (cpsd(x, y) ./ |cpsd(x,y)|).

Type: string

Outputs

tfe

The transfer function estimate values.

Type: vector

freq

The vector of frequencies corresponding to the transfer function estimate values.

Type: vector

Example

Use filtered noise to estimate the magnitude response of a 4th order Butterworth filter.

fc = 100;
fs = 1000;
[b, a] = butter(4, fc/(fs/2));
rand('seed', 2019)
signal1 = randn(1, 4096);
signal2 = filter(b, a, signal1);
tfestimate(signal1, signal2, 1024, 512, [], fs);

Figure 1. impz figure 1

Comments

With no return arguments, the function will automatically plot the tfe magnitudes.

The 'onesided' output has a length of nfft/2+1 if nfft is even, or (nfft+1)/2 if nfft is odd.

It is often recommended to remove the signal means prior to calling tfestimate. The function does not remove the mean automatically.