写出基于128点实数FFT实现单音检测的浮点C语言
时间: 2024-05-06 11:15:04 浏览: 107
以下是基于128点实数FFT实现单音检测的浮点C语言代码:
```c
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define N 128 // FFT点数
#define Fs 48000 // 采样率
#define F0 1000 // 待检测音频的频率
#define THRESHOLD 0.5 // 阈值
void fft(float* x, float* y) {
int i, j, k, n1, n2, a;
float c, s, t1, t2;
float twiddle[N/2][2];
// 初始化twiddle factors
for (i = 0; i < N/2; i++) {
twiddle[i][0] = cos(-2*M_PI*i/N);
twiddle[i][1] = sin(-2*M_PI*i/N);
}
// 原地FFT
for (i = 0; i < N; i++) {
j = 0;
k = i;
n1 = N;
while (n1 > 1 && k >= n1) {
k -= n1;
n1 >>= 1;
}
j = k + n1;
while (k < i) {
t1 = x[j] * twiddle[k][0] - y[j] * twiddle[k][1];
t2 = x[j] * twiddle[k][1] + y[j] * twiddle[k][0];
x[j] = x[i] - t1;
y[j] = y[i] - t2;
x[i] += t1;
y[i] += t2;
k += n1;
j = k + n1;
}
}
}
int main() {
int i, j, k;
float x[N], y[N], mag[N/2], max_mag;
int max_index;
// 生成待检测音频信号
float f[N];
for (i = 0; i < N; i++) {
f[i] = sin(2*M_PI*F0*i/Fs);
}
// 取前N个采样点进行FFT
for (i = 0; i < N; i++) {
x[i] = f[i];
y[i] = 0;
}
fft(x, y);
// 计算幅度谱
for (i = 0; i < N/2; i++) {
mag[i] = sqrt(x[i]*x[i] + y[i]*y[i]);
}
// 查找最大幅度和对应的下标
max_mag = 0;
for (i = 0; i < N/2; i++) {
if (mag[i] > max_mag) {
max_mag = mag[i];
max_index = i;
}
}
// 检测是否为待检测音频
if (max_mag/N > THRESHOLD) {
printf("检测到频率为%d的音频信号\n", max_index*Fs/N);
} else {
printf("未检测到待检测音频\n");
}
return 0;
}
```
注:该代码仅为示例,实际应用中需要考虑多个频率的检测、滤波等问题。