Tummas Tomasson / Mbed 2 deprecated PingDetector_mbedadc

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Dependencies:   mbed

PingDetect/FFT.cpp@0:efb27fbc92c0, 2012-07-30 (annotated)

Committer:
tummastt
Date:
Mon Jul 30 09:57:42 2012 +0000
Revision:
0:efb27fbc92c0
Child:
1:227db871d328
Working

Who changed what in which revision?

UserRevisionLine numberNew contents of line
tummastt 0:efb27fbc92c0 1 #include "FFT.h"
tummastt 0:efb27fbc92c0 2
tummastt 0:efb27fbc92c0 3 // Using the Mellen FFT
tummastt 0:efb27fbc92c0 4 extern "C" void fftR4(short *y, short *x, int N);
tummastt 0:efb27fbc92c0 5
tummastt 0:efb27fbc92c0 6 int FFT::DetectSignal(short data[]) {
tummastt 0:efb27fbc92c0 7
tummastt 0:efb27fbc92c0 8 CalculateFFT(data);
tummastt 0:efb27fbc92c0 9
tummastt 0:efb27fbc92c0 10 // adding the center frequencies with the 4 closesed frequencies
tummastt 0:efb27fbc92c0 11 // amp = my[centerFreq-2]+my[centerFreq]+my[centerFreq+2];
tummastt 0:efb27fbc92c0 12 amp = my[centerFreq-2]+my[centerFreq]+my[centerFreq+2];
tummastt 0:efb27fbc92c0 13 // return amp;
tummastt 0:efb27fbc92c0 14 if (amp >= AMPLITUDE_LIMIT)
tummastt 0:efb27fbc92c0 15 return found; // indicating pinger signal found
tummastt 0:efb27fbc92c0 16
tummastt 0:efb27fbc92c0 17 else
tummastt 0:efb27fbc92c0 18 return notFound; // indicating no pinger signal found
tummastt 0:efb27fbc92c0 19
tummastt 0:efb27fbc92c0 20 }
tummastt 0:efb27fbc92c0 21
tummastt 0:efb27fbc92c0 22 void FFT::CalculateFFT(short data[]) {
tummastt 0:efb27fbc92c0 23
tummastt 0:efb27fbc92c0 24 // Clearing array
tummastt 0:efb27fbc92c0 25 for (i=0; i<SAMPLES*2; i++)
tummastt 0:efb27fbc92c0 26 mx[i]=0;
tummastt 0:efb27fbc92c0 27
tummastt 0:efb27fbc92c0 28 // Add data to array
tummastt 0:efb27fbc92c0 29 for (i=0; i<SAMPLES; i=i+1)
tummastt 0:efb27fbc92c0 30 mx[i*2]=data[i]-DCOFFSET;
tummastt 0:efb27fbc92c0 31
tummastt 0:efb27fbc92c0 32 // calculate fft
tummastt 0:efb27fbc92c0 33 fftR4(my, mx, SAMPLES);
tummastt 0:efb27fbc92c0 34
tummastt 0:efb27fbc92c0 35 // make all values positive
tummastt 0:efb27fbc92c0 36 for (i=0; i<SAMPLES; i=i+2) {
tummastt 0:efb27fbc92c0 37 my[i] = abs(my[i]);
tummastt 0:efb27fbc92c0 38 }
tummastt 0:efb27fbc92c0 39 }