Initial sources

Makefile

@@ -0,0 +1,23 @@
+# Minimal makefile for Sphinx documentation
+#
+
+# You can set these variables from the command line.
+SPHINXOPTS    =
+SPHINXBUILD   = sphinx-build
+SOURCEDIR     = source
+BUILDDIR      = build
+
+# Put it first so that "make" without argument is like "make help".
+help:
+	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+
+.PHONY: help Makefile
+
+# Catch-all target: route all unknown targets to Sphinx using the new
+# "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
+%: Makefile
+	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+
+livehtml:
+	sphinx-autobuild -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
+

source/Analysis/107-tone-detection-with-goertzel.rst

@@ -0,0 +1,247 @@
+Tone detection with Goertzel
+============================
+
+- **Author or source:** on.biu.ii@rnepse
+- **Type:** Goertzel
+- **Created:** 2004-04-07 09:37:10
+
+- **Linked files:** :download:`http://www.ii.uib.no/~espenr/tonedetect.zip <../files/http://www.ii.uib.no/~espenr/tonedetect.zip>`.
+
+.. code-block:: text
+    :caption: notes
+
+    Goertzel is basically DFT of parts of a spectrum not the total spectrum as you normally do
+    with FFT. So if you just want to check out the power for some frequencies this could be
+    better. Is good for DTFM detection I've heard.
+    
+    The WNk isn't calculated 100% correctly, but it seems to work so ;) Yeah and the code is
+    C++ so you might have to do some small adjustment to compile it as C.
+
+
+.. code-block:: c++
+    :linenos:
+    :caption: code
+
+    /** Tone detect by Goertzel algorithm
+     *
+     * This program basically searches for tones (sines) in a sample and reports the different dB it finds for
+     * different frequencies. Can easily be extended with some thresholding to report true/false on detection.
+     * I'm far from certain goertzel it implemented 100% correct, but it works :)
+     * 
+     * Hint, the SAMPLERATE, BUFFERSIZE, FREQUENCY, NOISE and SIGNALVOLUME all affects the outcome of the reported dB. Tweak
+     * em to find the settings best for your application. Also, seems to be pretty sensitive to noise (whitenoise anyway) which
+     * is a bit sad. Also I don't know if the goertzel really likes float values for the frequency ... And using 44100 as
+     * samplerate for detecting 6000 Hz tone is kinda silly I know :)
+     * 
+     * Written by: Espen Riskedal, espenr@ii.uib.no, july-2002
+     */
+    
+    #include <iostream>
+    #include <cmath>
+    #include <cstdlib>
+
+    using std::rand;
+    // math stuff
+    using std::cos;
+    using std::abs;
+    using std::exp;
+    using std::log10;
+    // iostream stuff
+    using std::cout;
+    using std::endl;
+
+    #define PI 3.14159265358979323844
+    // change the defines if you want to
+    #define SAMPLERATE 44100
+    #define BUFFERSIZE 8820
+    #define FREQUENCY 6000
+    #define NOISE 0.05
+    #define SIGNALVOLUME 0.8
+
+    /**  The Goertzel algorithm computes the k-th DFT coefficient of the input signal using a second-order filter. 
+     *   http://ptolemy.eecs.berkeley.edu/papers/96/dtmf_ict/www/node3.html. 
+     *   Basiclly it just does a DFT of the frequency we want to check, and none of the others (FFT calculates for all frequencies).
+     */
+    float goertzel(float *x, int N, float frequency, int samplerate) {
+        float Skn, Skn1, Skn2;
+        Skn = Skn1 = Skn2 = 0;
+        
+        for (int i=0; i<N; i++) {
+    	Skn2 = Skn1;
+    	Skn1 = Skn;
+    	Skn = 2*cos(2*PI*frequency/samplerate)*Skn1 - Skn2 + x[i];
+        }
+
+        float WNk = exp(-2*PI*frequency/samplerate); // this one ignores complex stuff
+        //float WNk = exp(-2*j*PI*k/N);
+        return (Skn - WNk*Skn1);
+    }
+
+    /** Generates a tone of the specified frequency 
+     *  Gotten from: http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&selm=3c641e%243jn%40uicsl.csl.uiuc.edu
+     */
+    float *makeTone(int samplerate, float frequency, int length, float gain=1.0) {
+        //y(n) = 2 * cos(A) * y(n-1) - y(n-2)
+        //A= (frequency of interest) * 2 * PI / (sampling frequency)
+        //A is in radians.
+        // frequency of interest MUST be <= 1/2 the sampling frequency.
+        float *tone = new float[length];
+        float A = frequency*2*PI/samplerate;
+        
+        for (int i=0; i<length; i++) {
+    	if (i > 1) tone[i]= 2*cos(A)*tone[i-1] - tone[i-2];
+    	else if (i > 0) tone[i] = 2*cos(A)*tone[i-1] - (cos(A));
+    	else tone[i] = 2*cos(A)*cos(A) - cos(2*A);
+        }
+
+        for (int i=0; i<length; i++) tone[i] = tone[i]*gain;
+
+        return tone;
+    }
+
+    /** adds whitenoise to a sample */
+    void *addNoise(float *sample, int length, float gain=1.0) {
+        for (int i=0; i<length; i++) sample[i] += (2*(rand()/(float)RAND_MAX)-1)*gain;
+    }
+    
+    /** returns the signal power/dB */
+    float power(float value) {
+        return 20*log10(abs(value));
+    }
+    
+    int main(int argc, const char* argv) {
+        cout << "Samplerate: " << SAMPLERATE << "Hz\n";
+        cout << "Buffersize: " << BUFFERSIZE << " samples\n";
+        cout << "Correct frequency is: " << FREQUENCY << "Hz\n";
+        cout << " - signal volume: " << SIGNALVOLUME*100 << "%\n";
+        cout << " - white noise: " << NOISE*100 << "%\n";
+
+        float *tone = makeTone(SAMPLERATE, FREQUENCY, BUFFERSIZE, SIGNALVOLUME);
+        addNoise(tone, BUFFERSIZE,NOISE);
+    
+        int stepsize = FREQUENCY/5;
+
+        for (int i=0; i<10; i++) {
+    	int freq = stepsize*i;
+    	cout << "Trying freq: " << freq << "Hz  ->  dB: " << power(goertzel(tone, BUFFERSIZE, freq, SAMPLERATE)) << endl;
+        }
+        delete tone;
+
+        return 0;
+    }
+
+
+Comments
+--------
+
+- **Date**: 2002-08-25 16:53:33
+- **By**: ten.hte@ghsa
+
+.. code-block:: text
+
+    Hello!
+     I am interested in knowing that could we  implement the Goertzel algorithm using only integer variables and not using floa at all. Please let me know. I need it urgently.
+    regards,
+    Ashish
+                  
+
+- **Date**: 2003-02-24 17:21:53
+- **By**: rt.moc.siselet@ksunuy
+
+.. code-block:: text
+
+    Hello,
+    
+    I will implement DTMF/MFR1/MFR2 generation/detection function using DSP. I have found goertzel algorithm for DTMF. Can I use this algorithm for MFR1 and MFR2? Could you please let me know ?
+    Best Regards
+    Yunus
+    
+
+- **Date**: 2003-04-14 15:50:43
+- **By**: moc.liamtoh@faieasa
+
+.. code-block:: text
+
+     Hello
+     I'm going to implement a Goertzel algorithm on a Fixed_point DSP .
+     Could you lead me to the changes I should consider?
+     I realy appreciate your helping me.
+    
+    regards,
+    Afsaneh Asaei             
+
+- **Date**: 2003-06-12 04:51:59
+- **By**: ude.limaim.sismu@namhsifj
+
+.. code-block:: text
+
+    Does anybody know if and how this can be done in real time?
+    
+    Thanks,
+    JF
+
+- **Date**: 2003-11-24 12:15:16
+- **By**: no
+
+.. code-block:: text
+
+    It can.
+
+- **Date**: 2003-12-12 13:40:41
+- **By**: moc.liamoohay@802nahom_artibap
+
+.. code-block:: text
+
+    sir.
+    i m pabitra.
+    please help me to understand this program.        
+
+- **Date**: 2004-04-12 22:03:56
+- **By**: ed.luosfosruoivas@naitsirhC
+
+.. code-block:: text
+
+    yet untested Delphi translation of the algorithm:
+    
+    function Goertzel(Buffer:array of Single; frequency, samplerate: single):single;
+    var Skn, Skn1, Skn2 : Single;
+        i               : Integer;
+        temp1, temp2    : Single;
+    begin
+     skn:=0;
+     skn1:=0;
+     skn2:=0;
+     temp1:=2*PI*frequency/samplerate;
+     temp2:=Cos(temp1);
+     for i:=0 to Length(Buffer) do
+      begin
+       Skn2 = Skn1;
+       Skn1 = Skn;
+       Skn = 2*temp2*Skn1 - Skn2 + Buffer[i];
+      end;
+     Result:=(Skn - exp(-temp1)*Skn1);
+    end;
+    
+    Maybe someone can use it...
+    
+    Christian
+
+- **Date**: 2005-05-06 13:56:01
+- **By**: moc.eulgcimotabus@nivek
+
+.. code-block:: text
+
+    why's the 2*cos(2*PI*frequency/samplerate) in that inner loop?  It's all constants...  I'd precompute this outside the for loop.
+    
+    also.   use the float version of cos and exp... cosf expf... that way you're not wasting time converting and using the more expensive functions.
+
+- **Date**: 2005-06-19 07:16:52
+- **By**: moc.liamtoh@4002yad_ten
+
+.. code-block:: text
+
+    if anyone please can help me, i need a c++ code about the fft.the code should input and array of N rows and 1 column, all set to 1, and also it should input the length of fft(interval from f1 to f2) and output the results.
+    thank you,
+    i would appreciate your help,
+    bassem
+