Adding datetime to spectrogram x axis

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Louise Wilson
Louise Wilson 2022-2-15
评论： Star Strider 2022-2-16
I have six acoustic files which were recorded consecutively.
I have concatenated the data and shared it here: https://drive.google.com/drive/folders/11ZvIH6JhLJNDe_NrqIXJiM7EPqa08-7r?usp=sharing
I have plotted a spectrogram, but the x axis is in seconds and I would like it to be in a readable format, corresponding to the datetime LOCALDT variable.
% FFT parameters
Fs=48000;
dt = 1/Fs;
NFFT = 1624;
OVERLAP = 0.75;
% spectrogram dB scale
spectrogram_dB_scale = 80; % dB range scale (means , the lowest displayed level is XX dB below the max level)
%Time/frequency analysis (repeat for each axis)
signal=cell2mat(sample.xacc); %concatenate accel. data for all chunks
[samples,~] = size(signal);
[sg,fsg,tsg] = spectrogram(signal,hanning(NFFT),floor(NFFT*OVERLAP),NFFT,Fs);
sg_dBpeak = 20*log10(abs(sg))+20*log10(2/length(fsg)); % NB : X=fft(x.*hanning(N))*4/N; % hanning only
% saturation of the dB range :
% saturation_dB = 60; % dB range scale (means , the lowest displayed level is XX dB below the max level)
min_disp_dB = round(max(max(sg_dBpeak))) - spectrogram_dB_scale;
sg_dBpeak(sg_dBpeak<min_disp_dB) = min_disp_dB;
% plots spectrogram
imagesc(tsg,fsg,sg_dBpeak); %time, frequency, colour
colormap('jet');
axis('xy');%colorbar('vert');
colorbar
  1 个评论
Louise Wilson
Louise Wilson 2022-2-15
I have since realised I can do it like this...
xlim([0 30])
xticks([0 5 10 15 20 25 30])
xticklabels({'09:58:25','09:58:30','09:58:35','09:58:40','09:58:45','09:58:50'})
but I wonder if there is a more intuitive way...

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采纳的回答

Star Strider
Star Strider 2022-2-15
The spectrogram function uses surf to create its plots. In R2021b it accepts datetime values for the axis coordinates (see the documentation for X) and according to the online documentation, R2020b (X) supports it as well.
.
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Louise Wilson
Louise Wilson 2022-2-16
It's in the third line of the OP. I couldn't add the file here, it's 20 MB.

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