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| """ FMCW雷达CPD信号处理流程 基于TI AWR系列雷达芯片
参考:TI AWRL6432 Application Note Nazri et al., 2025 """
import numpy as np from typing import Tuple, Optional
class FMCW_CPD_Processor: """ FMCW雷达CPD信号处理器 用于检测车内儿童存在的信号处理流程 支持呼吸/心跳/运动三种检测模式 """ def __init__(self, config: dict): """ 初始化处理器 Args: config: 配置字典 - fc: 载频 (Hz), 60GHz - bw: 扫频带宽 (Hz), 4GHz - tc: 扫频时间 (s) - num_chirps: 每帧chirp数 - num_samples: 每chirp采样数 - fs: 采样率 (Hz) """ self.fc = config.get('fc', 60e9) self.bw = config.get('bw', 4e9) self.tc = config.get('tc', 50e-6) self.num_chirps = config.get('num_chirps', 128) self.num_samples = config.get('num_samples', 256) self.fs = config.get('fs', 5e6) self.c = 3e8 self.lambda_val = self.c / self.fc self.range_res = self.c / (2 * self.bw) self.vel_res = self.lambda_val / (2 * self.num_chirps * self.tc) def range_fft(self, adc_data: np.ndarray) -> np.ndarray: """ 距离维度FFT(快时间FFT) Args: adc_data: ADC采样数据, shape=(num_chirps, num_samples) Returns: range_profile: 距离剖面, shape=(num_chirps, num_samples) 每个chirp做FFT得到距离信息 """ window = np.hanning(self.num_samples) windowed = adc_data * window[np.newaxis, :] range_fft = np.fft.fft(windowed, axis=1) return range_fft def doppler_fft(self, range_fft_data: np.ndarray) -> np.ndarray: """ 多普勒FFT(慢时间FFT) Args: range_fft_data: 距离FFT结果, shape=(num_chirps, num_samples) Returns: range_doppler: Range-Doppler谱, shape=(num_chirps, num_samples) 跨chirp做FFT得到速度/微动信息 """ window = np.hanning(self.num_chirps) windowed = range_fft_data * window[:, np.newaxis] doppler_fft = np.fft.fftshift( np.fft.fft(windowed, axis=0), axes=0 ) return doppler_fft def extract_vital_signs( self, range_doppler: np.ndarray, target_range_bin: int ) -> Tuple[float, float, bool]: """ 从目标距离bin提取生命体征 Args: range_doppler: Range-Doppler谱 target_range_bin: 目标距离bin索引 Returns: breath_rate: 呼吸频率 (Hz) heart_rate: 心跳频率 (Hz) is_child: 是否判定为儿童 方法:从目标距离bin提取相位序列, 做频谱分析分离呼吸和心跳 """ phase_signal = np.angle( range_doppler[:, target_range_bin] ) phase_unwrapped = np.unwrap(phase_signal) phase_detrended = phase_unwrapped - np.polyval( np.polyfit(np.arange(len(phase_unwrapped)), phase_unwrapped, 1), np.arange(len(phase_unwrapped)) ) N = len(phase_detrended) freq = np.fft.fftfreq(N, d=self.tc * self.num_chirps) spectrum = np.abs(np.fft.fft(phase_detrended)) pos_mask = freq > 0 freq_pos = freq[pos_mask] spectrum_pos = spectrum[pos_mask] breath_mask = (freq_pos >= 0.2) & (freq_pos <= 0.6) breath_freq = freq_pos[breath_mask] breath_spectrum = spectrum_pos[breath_mask] breath_rate = breath_freq[np.argmax(breath_spectrum)] heart_mask = (freq_pos >= 0.8) & (freq_pos <= 2.0) heart_freq = freq_pos[heart_mask] heart_spectrum = spectrum_pos[heart_mask] heart_rate = heart_freq[np.argmax(heart_spectrum)] is_child = ( breath_rate > 0.4 and heart_rate > 1.2 and target_range_bin < 30 ) return breath_rate, heart_rate, is_child def mcsm_target_detection( self, range_doppler: np.ndarray ) -> int: """ MCSM算法:复杂环境下的目标距离检测 参考:Scientific Reports 2026, "A radar vital signs detection method in complex environments" Matrix Coefficient Selection Method 基于Range-Doppler谱的矩阵系数选择, 抑制静态杂波和非周期性动态干扰 Args: range_doppler: Range-Doppler谱 Returns: target_bin: 目标距离bin索引 """ rd_power = np.abs(range_doppler) ** 2 center_doppler = rd_power.shape[0] // 2 rd_power[center_doppler-1:center_doppler+2, :] = 0 rd_autocorr = np.zeros_like(rd_power) for r in range(rd_power.shape[1]): col = rd_power[:, r] col_centered = col - np.mean(col) if np.std(col) > 0: rd_autocorr[:, r] = col_centered mcsm_coeff = rd_power * np.abs(rd_autocorr) range_profile = np.sum(mcsm_coeff, axis=0) target_bin = np.argmax(range_profile) return target_bin
if __name__ == "__main__": config = { 'fc': 60e9, 'bw': 4e9, 'tc': 50e-6, 'num_chirps': 128, 'num_samples': 256, 'fs': 5e6 } processor = FMCW_CPD_Processor(config) print(f"距离分辨率: {processor.range_res*100:.2f} cm") print(f"波长: {processor.lambda_val*1000:.2f} mm") np.random.seed(42) t_chirp = np.linspace(0, config['tc'], config['num_samples']) t_frame = np.arange(config['num_chirps']) * config['tc'] breath_signal = 0.5 * np.sin(2 * np.pi * 0.3 * t_frame) heart_signal = 0.05 * np.sin(2 * np.pi * 1.2 * t_frame) vital_signal = breath_signal + heart_signal adc_data = np.random.randn(config['num_chirps'], config['num_samples']) * 0.1 for i in range(config['num_chirps']): adc_data[i, 50] += vital_signal[i] range_fft_data = processor.range_fft(adc_data) range_doppler = processor.doppler_fft(range_fft_data) target_bin = processor.mcsm_target_detection(range_doppler) breath_rate, heart_rate, is_child = processor.extract_vital_signs( range_doppler, target_bin ) print(f"\n检测结果:") print(f" 目标距离bin: {target_bin} ({target_bin * processor.range_res * 100:.1f} cm)") print(f" 呼吸频率: {breath_rate:.2f} Hz ({breath_rate*60:.1f} 次/分)") print(f" 心跳频率: {heart_rate:.2f} Hz ({heart_rate*60:.1f} 次/分)") print(f" 儿童判定: {'是' if is_child else '否'}")
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