FFT explanation for PREDMNT1 software on STWIN

[david binkowski]

Good morning,

I using STWIN for FFT analyse and i have few question about the data collection and especialy for understanding who does what

On STBLE app the logging from fft windows return 3 files (FFT amplitude, FFT and Motor time parameter). Is anybody have an explanation about their content for understanding how i can read and draw on excel the FFT.

By example what are the unit for amplitude column for file FFT ? how do the data are compiled?

i know that it exist design tips data sheet for sensortile but i haven't found yet for STWIN

thanks

[Eleon BORLINI]

Hi @david binkowski​ , this is the significance of the three files you get during the FFT log:

• FFT: this file contains the sequence of all the FFT of the three axis x, y and z calculated during the FFT log.
  • Frequency= 0 indicates the start of a new FFT.
• MotorTimeParameter: these parameters are the acc peak and the rms speed for the three axis and for each of the FFTs during the log time.
• FFT amplitude: it contains the raw data of the calculated FFTs, and should not be kept into account for the data analysis. In detail:
  • RawData: 2byte /* nSample */ + 1 byte /* nComponents */ + 4 byte /* Frequency Steps */ + ((3 * Size) * 4) byte /* Samples (X1,X2, … Xn, Y1,Y2, … Yn, Z1,Z2, … Zn) */

I believe that, since the STWIN kit is a very new tool, further online technical documentation will follow in the near future.

Regards