package com.nr.test.test_chapter13;
import static com.nr.NRUtil.SQR;
import static java.lang.Math.abs;
import static java.lang.Math.acos;
import static java.lang.Math.cos;
import static org.junit.Assert.fail;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import com.nr.sp.Spectreg;
import com.nr.sp.WelchWin;
public class Test_welch {
@Before
public void setUp() throws Exception {
}
@After
public void tearDown() throws Exception {
}
@Test
public void test() {
double maxf=0,maxs,pi=acos(-1.0),sbeps;;
int i,j,maxi=0,M=128,N=2*M,K=64;
double[] data=new double[N],spec=new double[M+1],freq=new double[M+1];
boolean localflag, globalflag=false;
// Test welch
System.out.println("Testing welch");
WelchWin welch = new WelchWin();
Spectreg sp = new Spectreg(M);
for (i=0;i<K;i++) {
// Generate a data set
for (j=0;j<N;j++)
data[j]=cos(2.0*pi*64*j/N);
sp.adddataseg(data,welch);
}
spec=sp.spectrum();
freq=sp.frequencies();
// for (i=0;i<M+1;i++)
// System.out.printf(freq[i] << " %f\n", spec[i]);
maxs=-1.0;
for (i=0;i<M+1;i++) {
if (spec[i] > maxs) {
maxf=freq[i];
maxs=spec[i];
maxi=i;
}
}
sbeps=1.e-15;
localflag=abs(maxf-0.25) > sbeps;
globalflag = globalflag || localflag;
if (localflag) {
fail("*** welch: Spectrum maximum is at wrong frequency");
}
// Test symmetry
sbeps=1.e-12;
localflag = false;
for (i=1;i<10;i++) {
// System.out.printf(abs(spec[maxi+i]/spec[maxi-i]-1.0));
localflag = localflag || abs(spec[maxi+i]/spec[maxi-i]-1.0) > sbeps;
}
globalflag = globalflag || localflag;
if (localflag) {
fail("*** welch: Channels adjacent to maximum should be symmetrical");
}
// Test amplitudes
sbeps=1.e-2;
localflag = false;
for (i=2;i<6;i++) {
// System.out.printf(abs(spec[maxi+i]/spec[maxi+1]*SQR(SQR(i))-1.0));
localflag = localflag || abs(spec[maxi+i]/spec[maxi+1]*SQR(SQR(i))-1.0) > sbeps;
globalflag = globalflag || localflag;
if (localflag) {
fail("*** welch: Sidelobe amplitudes are not in the correct proportion");
}
}
Spectreg sp2 = new Spectreg(M);
for (i=0;i<K;i++) {
// Generate a data set offset by 1/2 channel in frequency
for (j=0;j<N;j++)
data[j]=cos(2.0*pi*64.5*j/N);
sp2.adddataseg(data,welch);
}
spec=sp2.spectrum();
freq=sp2.frequencies();
// for (i=0;i<10;i++)
// System.out.printf(spec[maxi-i]/maxs << " %f\n", spec[maxi+i+1]/maxs);
sbeps=5.e-3;
localflag=false;
for (i=2;i<10;i++) {
localflag = localflag || abs(spec[maxi+i]/spec[maxi+1]) > sbeps;
// System.out.printf(abs(spec[maxi+i]/spec[maxi+1]));
}
globalflag = globalflag || localflag;
if (localflag) {
fail("*** welch: Leakage should be only into channels directly adjacent to peak");
}
if (globalflag) System.out.println("Failed\n");
else System.out.println("Passed\n");
}
}