title: How does Octave spectrogram 'specgram' from signal work?
body: <p>I'm trying to test the specgram function located in the signal package in Octave but I'm a little confused at the input/output variables for specgram.  What I would like to do is be able to get the specgram data into an array that will show the frequency and the length of time when the frequency starts and stops.</p>
  
  <p>See example code below: I was trying to get the array to show that for the length of t1 it will be 7hz, t2 will be 12hz and for t3 will be 2hz.  How can I go about doing this?</p>
  
  <p>I'm using ubuntu 12.04 and octave 3.2.4 and the signal package 1.0.11</p>
  
  <pre><code>% combines sig with spectra plot
  clear all,clc,tic;
  fs=1000;
  t1=linspace(0,2*pi,fs/0.1); %need to round off no decimals
  t2=linspace(0,2*pi,fs/0.3); %need to round off no decimals
  t3=linspace(0,2*pi,fs/0.6); %need to round off no decimals
  
  %Create signal in different arrays
  y1=sin(7*t1);
  y2=sin(12*t2);
  y3=sin(2*t3);
  
  %append arrays to test specgram
  yt = [y1 y2 y3];
  
  %plot(yt) %will show combined plot
  
  %Spectrum section
  yts=specgram(yt',20,500, 2,1);
  plot(yts)
  fprintf('\nfinally Done-elapsed time -%4.4fsec- or -%4.4fmins- or -%4.4fhours-\n',toc,toc/60,toc/3600);
  </code></pre>