Remove seismometer signal from the transfer function of the instrument
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Dear All,
i need to remove a seismometer signal, in displacements, from the transfer function of the instrument.
Can you suggest me how to do it?
Thank you in advance.
3 Comments
Mathieu NOE
on 10 May 2021
hello
so you have indeed already a transfer function .... but I don't get what it means "removing a signal from a tf" ??
it's like comparing apples and oranges.. you can do math between signals or tfs , but between a signal and a tf the only thing I can do is to filter a given signal by a tf , but that has nothing to do with "removing" ...
is this an homework ? do you have a more refined explanation of what is the intention of this ?
all the best
Answers (1)
Alessio Lodato
on 10 May 2021
2 Comments
Mathieu NOE
on 10 May 2021
hello Alessio
look at filter and filtfilt to filter a signal by a given transfer function
Star Strider
on 10 May 2021
This is a problem generally with instrumentation. The instrument (in this instance a seismometer) has its own characterisrtics, and filters the ground motion presented to it according to those characteristics. It is possible to estimate the transfer function of the seismometer if a record of its responses to a specific input (ideally an impulse of known amplitude) is available.
With respect to ambient recordings however, the ‘inverse problem’ — reconstructing the original signal from the recorded signal and the transfer function of the transducer — is generally not possible, simply because the frequencies not present in the recorded signal (filtered out by the transducer dynamics) are lost forever.
I have not worked with seismometers, however I have worked with physiological instrumentation, and encountered this problem in that context. I am not aware that there is any solution for it.
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