Unsmooth linear acceleration data

[Jim123321]

Hi! I'm working on an experiment that requires me to collect acceleration data. I put my phone on the object and get the acceleration data by the phyphox app. However, when processing the data, I often find some data points behave strange, such as suddenly drop dramatically when that trend of other acceleration points are at upward trend. Is this the app problem or the inaccuracy of the builtin accelerometer or the problem of my experiment? I think at least I should get a smooth acceleration data.


For example, this is the whole experiment data plot, the data points do follow some trend (I added a screenshot):
   


However, when I zoom in, some data points are strange sometimes(I added a screenshot).