/* File Dsp032.java
Copyright 2004, R.G.BaldwinRevised 5/17/2004
Performs spectral analysis on five separate timeseries, each 400 samples in length.
Each time series contains a pulse and the pulsesare different lengths.
Each pulse consists of the sum of two sinusoidsat closely spaced frequencies. The frequencies
of the two sinusoids for all pulses are the same.All frequency values are specified as type
double as a fraction of the sampling frequency.The frequencies of the two sinusoids are
equidistant from 0.0625 times the samplingfrequency.
The frequency of one sinusoid is(0.0625 - 2.0/len) times the sampling frequency.
The frequency of the other sinusoid is(0.0625 + 2.0/len) times the sampling frequency.
The lengths of the pulses are:25 samples
50 samples100 samples
200 samples400 samples
The spectral analysis computes the spectra at400 equally spaced points between zero and the
folding frequency (one-half the samplingfrequency).
The results of the spectral analysis aremultiplied by the reciprocal of the lengths of
the individual pulses to normalize the fiveplots. Otherwise, the results for the short
pulses would be too small to see on the plots.Tested using J2SEE 1.4.2 under WinXP.
************************************************/import java.util.*;
class Dsp032 implements GraphIntfc01{final double pi = Math.PI;
int len = 400;//data length//Sample that represents zero time.
int zeroTime = 0;//Low and high frequency limits for the
// spectral analysis.double lowF = 0.0;
double highF = 0.5;int numberSpectra = 5;
//Frequencies of the sinusoidsdouble freq1 = 0.0625 - 2.0/len;
double freq2 = 0.0625 + 2.0/len;//Amplitude of the sinusoids
double amp = 160;//Following arrays will contain data that is
// input to the spectral analysis process.double[] data1 = new double[len];
double[]data2 = new double[len];double[] data3 = new double[len];
double[]data4 = new double[len];double[] data5 = new double[len];
//Following arrays receive information back// from the spectral analysis that is not used
// in this program.double[] real;double[] imag;double[] angle;//Following arrays receive the magnitude// spectral information back from the spectral
// analysis process.double[] mag1;double[] mag2;double[] mag3;double[] mag4;double[] mag5;public Dsp032(){//constructor
//Create the raw datafor(int x = 0;x<len/16;x++){
data1[x]= amp*Math.cos(2*pi*x*freq1)
+ amp*Math.cos(2*pi*x*freq2);}//end for loop
for(int x = 0;x<len/8;x++){
data2[x]= amp*Math.cos(2*pi*x*freq1)
+ amp*Math.cos(2*pi*x*freq2);}//end for loop
for(int x = 0;x<len/4;x++){
data3[x]= amp*Math.cos(2*pi*x*freq1)
+ amp*Math.cos(2*pi*x*freq2);}//end for loop
for(int x = 0;x<len/2;x++){
data4[x]= amp*Math.cos(2*pi*x*freq1)
+ amp*Math.cos(2*pi*x*freq2);}//end for loop
for(int x = 0;x<len;x++){
data5[x]= amp*Math.cos(2*pi*x*freq1)
+ amp*Math.cos(2*pi*x*freq2);}//end for loop
//Compute magnitude spectra of the raw data// and save it in output arrays. Note that
// the real, imag, and angle arrays are not// used later, so they are discarded each
// time a new spectral analysis is performed.mag1 = new double[len];real = new double[len];imag = new double[len];angle = new double[len];ForwardRealToComplex01.transform(data1,real,
imag,angle,mag1,zeroTime,lowF,highF);mag2 = new double[len];real = new double[len];imag = new double[len];angle = new double[len];ForwardRealToComplex01.transform(data2,real,
imag,angle,mag2,zeroTime,lowF,highF);mag3 = new double[len];real = new double[len];imag = new double[len];angle = new double[len];ForwardRealToComplex01.transform(data3,real,
imag,angle,mag3,zeroTime,lowF,highF);mag4 = new double[len];real = new double[len];imag = new double[len];angle = new double[len];ForwardRealToComplex01.transform(data4,real,
imag,angle,mag4,zeroTime,lowF,highF);mag5 = new double[len];real = new double[len];imag = new double[len];angle = new double[len];ForwardRealToComplex01.transform(data5,real,
imag,angle,mag5,zeroTime,lowF,highF);}//end constructor
//-------------------------------------------////The following six methods are required by the
// interface named GraphIntfc01.public int getNmbr(){
//Return number of functions to process.// Must not exceed 5.
return 5;}//end getNmbr
//-------------------------------------------//public double f1(double x){
int index = (int)Math.round(x);if(index<0 || index>mag1.length-1){
return 0;}else{
//Scale the magnitude data by the// reciprocal of the length of the sinusoid
// to normalize the five plots to the same// peak value.
return mag1[index]*16.0;
}//end else}//end function
//-------------------------------------------//public double f2(double x){
int index = (int)Math.round(x);if(index<0 || index>mag2.length-1){
return 0;}else{
return mag2[index]*8.0;
}//end else}//end function
//-------------------------------------------//public double f3(double x){
int index = (int)Math.round(x);if(index<0 || index>mag3.length-1){
return 0;}else{
return mag3[index]*4.0;
}//end else}//end function
//-------------------------------------------//public double f4(double x){
int index = (int)Math.round(x);if(index<0 || index>mag4.length-1){
return 0;}else{
return mag4[index]*2.0;
}//end else}//end function
//-------------------------------------------//public double f5(double x){
int index = (int)Math.round(x);if(index<0 || index>mag5.length-1){
return 0;}else{
return mag5[index]*1.0;
}//end else}//end function
}//end sample class Dsp032 |
