How to find out if any signal has a noise signal and if so in what range?

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Mehmet Rizelioglu
Mehmet Rizelioglu 2021-12-12
评论： Mehmet Rizelioglu 2021-12-14
Hi guys,
I have an accelerometer signal and how do I know if there is no noise signal in this signal. Also, if there is noise, in what frequency range was it?
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Walter Roberson
Walter Roberson 2021-12-12
A rule of thumb:
If you can afford to buy the accelerometer for personal use, without charging it as a business expense... then the signal probably has noise.
https://en.wikipedia.org/wiki/Inertial_measurement_unit#Performance
A very wide variety of IMUs exists, depending on application types, with performance ranging:[12]
from 0.1°/s to 0.001°/h for gyroscope
from 100 mg to 10 µg for accelerometers.
To get a rough idea, this means that, for a single, uncorrected accelerometer, the cheapest (at 100 mg) loses its ability to give 50-meter accuracy after around 10 seconds, while the best accelerometer (at 10 µg) loses its 50-meter accuracy after around 17 minutes.

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回答（3 个）

Matt Gaidica
Matt Gaidica 2021-12-12
编辑：Matt Gaidica 2021-12-12
Mehmet, do you have a recording from the accelerometer at rest and is that the condition which you want to test for 'noise' against? I think you might find some help here: https://stackoverflow.com/questions/67992691/how-to-calculate-95-confidence-level-of-fourier-transform-in-python
If it were me, I might record 1,000 seconds from the accelerometer, split that into 1-second recordings, perform an FFT on each, and create my own confidence interval for each frequency bin (this, of course, depends on your sampling rate). Then you could easily apply your own criteria to determine if there is some extra signal and at which frequencies it exceeds some confidence/alpha/p-value of your choosing.
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Image Analyst
Image Analyst 2021-12-13
@Mehmet Rizelioglu did you see my suggestion below? Alternatively, can you attach two or more accelerometers to your object and average their values to try to beat down the noise?

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Walter Roberson
Walter Roberson 2021-12-12
I have an accelerometer signal and how do I know if there is no noise signal in this signal.
There is noise in all accelerometer signals, even the very best of them.
You cannot use only an accelerometer for accurate "dead reckoning": you need an Inertial Navigation System (INS) for that, and it takes a fair bit of work to combine information from multiple sensor types in order to get accurate position information. https://en.wikipedia.org/wiki/Inertial_navigation_system#Drift_rate
If you ever see a manufacturer claim that they have "no" noise in their accelerometers, then they are... mistaken.
Image Analyst
Image Analyst 2021-12-13
Yes, your accelerometer has noise -- all instruments do.
You can look at the signal spectrum with the device not moving. Presumably this signal is just all noise. Use fft() or pwelch(). However the noise may be different when it's still versus when it's moving. So then do that again with the accelerometer moving in a typical motion that you will use. Compare the two spectra and see what frequency range they are different in. Attach your signals if you need more help.
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Mehmet Rizelioglu
Mehmet Rizelioglu 2021-12-14
Hi, not moving as 2 seconds, then starts moving. i have sent you my data's FFT and PSD. I would be very grateful if you could take a look at it in your free time.

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