// Assuming you're inside your main loop
if (is_data_ready_for_fft == 1) {
    // Copy fft_in to the matrix row corresponding to the current chirp
    for (size_t i = 0; i < ADC_BUF_LENGTH; i++) {
        fft_matrix[chirp_index][i] = fft_in[i];
    }

    // Process the FFT as usual
    is_data_ready_for_fft = 0;
    arm_rfft_fast_f32(&fft_handler, fft_in, fft_out, 0);
    arm_cmplx_mag_f32(fft_out, fft_out2, ADC_BUF_LENGTH);
    fft_out2[0] = 0;
    arm_max_f32(fft_out2, ADC_BUF_LENGTH/2, &Result, &Index);

    R = (300000000 * 0.004064 * Index) / 500000000;

    // Increment the chirp index
    chirp_index++;

    // Reset if you've captured all chirps
    if (chirp_index >= 20) {
        chirp_index = 0; // or handle it depending on your needs
    }
}

// Assuming you're inside your main loop
if (is_data_ready_for_fft == 1) {
    // Copy fft_in to the matrix row corresponding to the current chirp
    for (size_t i = 0; i < ADC_BUF_LENGTH; i++) {
        fft_matrix[chirp_index][i] = fft_in[i];
    }

    // Process the FFT as usual
    is_data_ready_for_fft = 0;
    arm_rfft_fast_f32(&fft_handler, fft_in, fft_out, 0);
    arm_cmplx_mag_f32(fft_out, fft_out2, ADC_BUF_LENGTH);
    fft_out2[0] = 0;
    arm_max_f32(fft_out2, ADC_BUF_LENGTH/2, &Result, &Index);

    R = (300000000 * 0.004064 * Index) / 500000000;

    // Increment the chirp index
    chirp_index++;

    // Reset if you've captured all chirps
    if (chirp_index >= 20) {
        chirp_index = 0; // or handle it depending on your needs
    }
}