/**
* Determines if a power value is a peak at the spectrum. Compares it with the two frequency bins
* above and below.
*
* @param index The index location to test inside the current list of valid frequencies.
* @return True if it is a peak at that frequency, else false.
* @throws IndexOutOfBoundsException If the given index forces a comparison out of bounds
*/
private boolean isPeakAt(int index) throws IndexOutOfBoundsException {
int frequency = validFrequencies.get(index); // get the frequency at the point.
double power = freqPower[frequency];
for (int i = (-3 + index); i <= (3 + index); i++) {
if (i >= 0 && i < validFrequencies.size() && i != index) {
int oFrequency = validFrequencies.get(i);
double oPower = freqPower[oFrequency];
double dp = power - oPower;
if (dp < PEAK_THRESHOLD) return false;
}
}
return true;
}
/** Extracts the local peaks from the spectrum at this particular time interval. */
private void getLocalPeaks() {
for (int i = 0; i < validFrequencies.size(); i++) {
try {
if (isPeakAt(i)) {
int frequency = validFrequencies.get(i); // get the frequency at the particular index
Peak peak = new Peak(spectrumNumber, frequency, freqPower[frequency]);
// System.out.println(spectrumNumber + " " + frequency);
peaks.add(peak);
// System.out.println(peak.getTime() + " " + peak.getFrequency());
}
} catch (IndexOutOfBoundsException e) {
// do nothing
}
}
}
/**
* Cycles through the array of power values and gets rid of all the values less than the average
* power for the interval.
*/
private void filterPeaks() {
validFrequencies = new ArrayList<Integer>(); // list of frequencies with power > average power
for (int frequency = 0; frequency < freqPower.length; frequency++) {
double thisPower = freqPower[frequency];
if (thisPower > averagePower) {
validFrequencies.add(
frequency); // add to the list of valid frequencies if greater than average power
}
}
getLocalPeaks();
}