CA-CFAR C语言实现

CA-CFAR (Cell Averaging - Constant False Alarm Rate) 是一种雷达信号处理技术，用于检测雷达信号中的目标。以下是一份 C 语言实现代码示例：

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define PI 3.14159265358979323846

void cfar_ca(int n, double *x, int nwin, int nguard, int ntarget, double guard_factor, double target_factor, double *y)
{
    int i, j, k;
    int ncell = n - nwin + 1;
    int nguard = (int)floor(nguard * guard_factor + 0.5);
    int ntarget = (int)floor(ntarget * target_factor + 0.5);
    double *win = (double *)malloc(nwin * sizeof(double));
    double *sum = (double *)malloc((ncell + 2 * nguard) * sizeof(double));
    double noise_level, thresh;

    // Generate the window function
    for (i = 0; i < nwin; i++) {
        win[i] = 0.5 - 0.5 * cos(2 * PI * i / (nwin - 1));
    }

    // Compute the running sum of the windowed data
    for (i = 0; i < ncell + 2 * nguard; i++) {
        sum[i] = 0.0;
        for (j = i - nguard; j < i - nguard + nwin; j++) {
            sum[i] += x[j] * win[j - i + nguard];
        }
    }

    // Compute the average noise level
    noise_level = 0.0;
    for (i = nguard; i < ncell + nguard; i++) {
        noise_level += sum[i];
    }
    noise_level /= ncell;

    // Compute the threshold level
    thresh = noise_level * pow(10.0, target_factor / 10.0);

    // Detect the targets
    k = 0;
    for (i = nguard; i < ncell + nguard; i++) {
        if (sum[i] > thresh) {
            for (j = i - nguard; j < i - nguard + nwin; j++) {
                y[k++] = x[j];
            }
        }
    }

    // Free the memory
    free(win);
    free(sum);
}

int main()
{
    int n = 1000;
    double *x = (double *)malloc(n * sizeof(double));
    double *y = (double *)malloc(n * sizeof(double));
    int nwin = 64;
    int nguard = 16;
    int ntarget = 4;
    double guard_factor = 1.5;
    double target_factor = 10.0;

    // Generate the test data
    for (int i = 0; i < n; i++) {
        x[i] = rand() / (RAND_MAX + 1.0);
    }

    // Apply the CFAR algorithm
    cfar_ca(n, x, nwin, nguard, ntarget, guard_factor, target_factor, y);

    // Print the results
    printf("Input data:\n");
    for (int i = 0; i < n; i++) {
        printf("%f\n", x[i]);
    }

    printf("Output data:\n");
    for (int i = 0; i < n; i++) {
        if (y[i] != 0.0) {
            printf("%f\n", y[i]);
        }
    }

    // Free the memory
    free(x);
    free(y);

    return 0;
}

在上面的代码中，`cfar_ca` 函数接受以下参数：

- `n`：输入信号的长度。
- `x`：输入信号的指针。
- `nwin`：窗口大小。
- `nguard`：警戒区大小。
- `ntarget`：目标数量。
- `guard_factor`：警戒系数。
- `target_factor`：目标系数。
- `y`：输出信号的指针。

该函数会将检测到的目标存储在 `y` 数组中，其他位置的值为 0。可以根据需要修改输出格式和其他参数。