Correlation experiments. Construct a test-input with 6000 samples of Gold26, find the match-point and use 1/4 chips spacing

 ```public void fillArray13() { // correlation experiments // construct a test-input with 6000 samples of Gold26 // find the match-point // now use 1/4 chips spacing int shift = 3600; // display only most interesting part int inplen = 6000; int[] testinput = new int[inplen]; int[] bins = new int[inplen]; System.out.println("experiment 13. Correlation 1/4 chips spacing"); GoldSequence gold26 = new GoldSequence(2,6); // throw away first 35 chips for (int i = 0; i < 35; i++) { gold26.nextan4(); } for (int i = 0; i < testinput.length; i++) { testinput[i] = gold26.nextan4(); } gold26.reset(); // this is an implimentation of a correlator for (int i = 0; i < inplen; i++) { gold26.reset(); int acc = 0; for (int j = 0; j < 1023; j++) { if ((i + j) < inplen) { acc = acc + testinput[i + j] * gold26.nextan4(); } } bins[i] = acc; } plotData = new double[1268]; for(int i=0; i<1268; i++) { plotData[i] = bins[i + shift]; System.out.println(i + " " + plotData[i]); } } ```

And this results in the following beautiful graphic output:

Where is the peak? Throw away the first 35 samples. With 1/4 chips spacing there are 4*1023=4092 samples. So after 4092 - 35 = 4057 there will be a peak. With a shift of 3600 the peak in the display is at bin 4057 - 3600 = 457. The triangle shape is clearly visible.

A more sophisticated correlation experiment. Construct a test-input with 6000 samples of Gold26, find the match-point. Now use 1/4 chips spacing and add Gaussian noise. Negative sign of input-PRN

 ```public void fillArray14() { // correlation experiments // construct a test-input with 6000 samples of Gold26 // find the match-point // now use 1/4 chips spacing // and add Gaussian noise // negative sign of input-PRN int shift = 3600; // display only most interesting part int inplen = 6000; double[] testinput = new double[inplen]; double[] bins = new double[inplen]; Random r = new Random(); int noise = 5; int sign = -1; System.out.println("experiment 14. Correlation 1/4 chips spacing" + " and Gaussian noise added"); GoldSequence gold26 = new GoldSequence(2,6); // throw away first 35 chips for (int i = 0; i < 35; i++) { gold26.nextan4(); } for (int i = 0; i < testinput.length; i++) { testinput[i] = sign * gold26.nextan4() + noise * r.nextGaussian(); } gold26.reset(); // this is an implimentation of a correlator for (int i = 0; i < inplen; i++) { gold26.reset(); double acc = 0; for (int j = 0; j < 1023; j++) { if ((i + j) < inplen) { acc = acc + testinput[i + j] * gold26.nextan4(); } } bins[i] = acc; } plotData = new double[1268]; for(int i=0; i<1268; i++) { plotData[i] = bins[i + shift]; System.out.println(i + " " + plotData[i]); } } ```

The corresponding output is:

The peak is, again, at bin 457. The program is in fact the same as the previous example