When reading a spectrogram, why is a power of 20 considered higher than 120

Question

fadams18 2022-9-7

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1799140-when-reading-a-spectrogram-why-is-a-power-of-20-considered-higher-than-120

评论： fadams18 2022-9-7

Looking at the spectrogram below, it appears the higher power in the cyan color. but its power value is around 20.

why is this the case? does lower value mean big power?

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2022-9-7

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1799140-when-reading-a-spectrogram-why-is-a-power-of-20-considered-higher-than-120#answer_1046790

Those are not 20 and 120: those are -20 and -120 .

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

fadams18 2022-9-7

在 MATLAB Online 中打开

I did a similar plot with a different signal. but my colorbar seems to be inverted. or u reckon its the right way?

[S, feqStft, timeStft] = MyStft(x,win,hop, nfft, fs);
magStft = abs(S);
imagesc(timeStft, feqStft, mag2db(magStft));
colorbar;
set(gca, 'YDir', 'normal');
title('Original Spectrogram of Signal ');
xlabel(['Time (0 - ', num2str(timeStft(end)), ' seconds)']);
ylabel(['Freq (0 - ', num2str(feqStft(end)), ' Hz)']);