psd ----> spectrum psd?

Hi

I try to run this prog.

http://www.auditory.org/mhonarc/2000/msg00498.html

du calc. the specific loudness based on the zwicker model.

Whenn I run the prog. i get this back:

"Undefined function 'psd' for input arguments of type 'double'"

the Note in the Editor says

"The function PSD is deprecated. Use SPECTRUM.PSD instead.

What to do?

Answer 1

[Honglei Chen]

You need to replace psd call with corresponding spectrum.psd code. Here is an example showing how to use spectrum.psd to compute PSD of a signal

Fs = 1000;
t = 0:1/Fs:.3;
x=cos(2*pi*t*200)+randn(size(t));
Hs=spectrum.periodogram;
psd(Hs,x,'Fs',Fs)

More details at http://www.mathworks.com/help/toolbox/signal/ref/spectrum.html

Answer 2

[Redkap]

thanks for advice, but can't follow you.

this is the m file

% PowSpec.m
%
%  Methodology:
%
%  Syntax:
%  [Yxx,f]=PowSpec(y,fs,df)
%
%  Variables:
%  INPUT
%  y      =  Time signal
%  fs      =  Sampling frequency
%  df      =  DESIRED df
%
%  WORKING
%  NFFT    =  Nummber of points for a given fft
%  NOVERLAP  =  Number of Points to overlap
%
%  OUTPUT
%  Yxx    =  Power Spectrum Amplitude
%  f      =  Frequency vector of power spectrum

%  Author:  Aaron Hastings, Herrick Labs, Purdue University
%  Date Started:  11 Nov 00
%  Last Revision:  11 Nov 00
%  Status: No Known Bugs

function [Yxx,f]=PowSpec(y,fs,df);

%%Want to make sure that we have at least df resolution
NFFT=ceil(fs/df);  
%%Set NFFT to power of 2 again err towards higher resolution
NFFT=2^ceil(log2(NFFT));

    NOVERLAP=0;
    [Yxx,f] = psd(y,NFFT,fs,NFFT,NOVERLAP);
    Yxx=2*Yxx/NFFT;  %%Scale to get the power spectrum correct
    Yxx=Yxx';

    return

Answer 3

[Honglei Chen]

You will replace line

[Yxx,f] = psd(y,NFFT,fs,NFFT,NOVERLAP);

with

hspec = spectrum.welch('OverlapPercent',0,'SegmentLength',NFFT);
hpsd = psd(hspec,y,'NFFT',NFFT,'Fs',fs);
Yxx = hpsd.Data;
f = hpsd.Frequencies

Alternatively, you may also use

[Yxx,f] = pwelch(y,NFFT,0,NFFT,fs);

Answer 4

[Redkap]

sorry to bother again,

it' still not working:

[Yxx,f]=PowSpec(y,fs,df);

%%Want to make sure that we have at least df resolution
NFFT=ceil(fs/df);  
%%Set NFFT to power of 2 again err towards higher resolution
NFFT=2^ceil(log2(NFFT));

NOVERLAP=0;
hspec = spectrum.welch('OverlapPercent',0,'SegmentLength',NFFT);
hpsd = psd(hspec,y,'NFFT',NFFT,'Fs',fs);
Yxx = hpsd.Data;
f = hpsd.Frequencies;
Yxx=2*Yxx/NFFT;  %%Scale to get the power spectrum correct
Yxx=Yxx';

return
Undefined variable "spectrum" or class "spectrum.welch".

Error in PowSpec (line 35)
hspec = spectrum.welch('OverlapPercent',0,'SegmentLength',NFFT);

Answer 5

[Wayne King]

Hi Redkap, Honglei has been giving you very good advice here. What version of MATLAB are you using and do you have the Signal Processing Toolbox?

If you enter

>>which spectrum.welch

What do you get returned?

Something is wrong if you cannot execute this line:

plot(psd(spectrum.welch,randn(1e3,1)))

Can you copy and paste the above line into your workspace and see what happens?

Also, please tell us your version and make sure:

license('test','signal_toolbox')

returns a 1.

By the way, in:

hspec = spectrum.welch('OverlapPercent',0,'SegmentLength',NFFT);
hpsd = psd(hspec,y,'NFFT',NFFT,'Fs',fs);
Yxx = hpsd.Data;
f = hpsd.Frequencies;
Yxx=2*Yxx/NFFT;  %%Scale to get the power spectrum correct
Yxx=Yxx';

You do not need to scale the output of the spectrum objects. That output is already properly scaled to be the PSD estimate so just use hpsd.Data and hpsd.Frequencies

[Elisabeth Debusschere]

I have the same problem, and checked the plot(psd(spectrum.welch,randn(1e3,1))) and the license

This is what I get

hspec = spectrum.welch('OverlapPercent',0,'SegmentLength',NFFT);

Error using spectrum.welch (line 52)

what is wrong?

Too many input arguments.