语音信号预处理4——绘制接滤波后chirp信号的时域图和频域图

article/2025/10/3 23:52:32

写在前面：仅作为个人学习笔记，便于以后查阅，如对你有帮助，荣幸之至，如有错误，欢迎评论指正

编程软件：matlab R2018b
系统： win10

系列文章目录

chirp信号的生成与接收
对接收到的chirp信号进行滤波、分帧处理及端点检测
计算原始chirp信号与滤波后chirp信号的相关性
绘制接滤波后chirp信号的时域图和频域图
从1-4完整走一遍

文章目录

- - 系列文章目录
  - 时域图
  - 频域图
  - 参考文献

时域图

直接上代码上图，因为回声信号可能有很多个，所以我只截取了一段回声信号进行展示：

%% 截取一段回声信号
i = 1;
invaildTime = 0.0138; vaildTime = 0.0800;  %set the vaild time of real echo   % invaildTime = 0.0138; vaildTime = 0.0862;
invaildLen = round(invaildTime * fs); vaildLen = round(vaildTime * fs); %get the real echo' length
startIndex = (voiceseg(i).begin - 1) * inc + invaildLen;
endIndex = startIndex + vaildLen;
% startIndex = (voiceseg(i).begin - 1) * inc;
% endIndex = startIndex + chirpInterval * fs;
% echo = xPoly(startIndex : endIndex);   %回声信号
echo = xFilter(startIndex : endIndex);
% echoEnvelop = abs(echo+(1i)*hilbert(echo)); %get the envelop of this echo segment
echoTime = time(startIndex : endIndex); 
% figure(2);
subplot(2, 2, 2);
plot(echoTime, echo);
grid;
% ylabel('归一化幅值');
ylabel('幅值');
xlabel(['样本点' 10 '(b)']);
title('一段回声信号');%%% compute the correlation between echo and raw audio signal
corrEcho = matched_filter_compute(echo, sampleSignal);
corrEcho = corrEcho / max(corrEcho);
timeEcho = 0 : length(corrEcho) - 1;
timeEcho = timeEcho/fs;
subplot(2, 2, 3);
plot(timeEcho, corrEcho);
grid;
title('回声的相关性');
% ylabel('归一化幅值');
ylabel('幅值');
xlabel(['样本点' 10 '(c)']);
hold on;

一段回声信号的时域图如下所示，横坐标时样本点序列，横坐标是信号的幅值：

频域图

上代码上图：

%% compute the fft
%%% get the echo array
echoData = echo;
[f_vec, amp] = fftCompute(echoData, fs);
freqArr = zeros(length(f_vec), k); % store echo valid echo data);
freqArr( : , 1) = amp;% for i = 2 : chirpRepeat
for i = 2 : kstartIndex = (voiceseg(i).begin - 1) * inc + invaildLen;endIndex = startIndex + vaildLen;
%     echoData = xPoly(startIndex : endIndex);echoData = xFilter(startIndex : endIndex);[f_vec, amp] = fftCompute(echoData, fs);freqArr( : , i) = amp;
end
freqMean = sum(freqArr, 2);
freqMean = freqMean / k;
% freqMean = freqMean / max(abs(freqMean));subplot(2, 2, 4);
plot(f_vec, freqMean);
xlabel(['频率/HZ']);
ylabel('幅度');
title('频域图');