Combination of two signals with different sample rates

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Sotiris Katsimentes 2022-6-10

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https://ww2.mathworks.cn/matlabcentral/answers/1737935-combination-of-two-signals-with-different-sample-rates

回答： Peter Perkins 2022-6-13

Hello,

I want to combine two signals with different sampling rate. I have have 2 sound signals, one (A) has telephone quality (Fs = 8Kz) and the other (B) music CD quality(Fs = 44.1 KHz). I want to add the music from file B to file A as a music investment (need someweakening). The duration of the result is equal to the longer of A and B.

How i can manage it??

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Star Strider 2022-6-11

Do not resample the signal with the lower sampling frequency to the higher sampling frequency, because that creates data where none previously existed. Instead, resample the signal with the higher sampling frequency to the lower sampling frequency.

Mathieu NOE 2022-6-13

编辑：Mathieu NOE 2022-6-13

hmmm

that depends if the signal sampled at 44.1 kHz should not be downsampled because it contains valuable info in the high frequency range ( 4 to 22 kHz)

beside that , upsampling does not create "noticable" / bad info's if it's done correctly :

for real time upsampling : insert zero elements AND then low pass filter (see for example : slidesSampling.dvi (toronto.edu)
for non real time upsampling : you can do the same , or simply interpolation. A higher order interpolation will almost create zero artifacts / info in the "new" frequency range. You can try it , do the upsampling and make the fft of the upsampled signal vs the original signal. You will end up will a almost zero fft amplitude in the extended frequency range. BTW, interp1 does not require any toolbox.

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回答（1 个）

Peter Perkins 2022-6-13

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Use a timetable, and call synchronize. synchronize uses interp1, but it may be that you particularly want to use the SP-oriented resample function instead:

ttHighFreq.yUpsampled = resample(ttLowFreq.y,...)