Experiment: Magnetic Spectrum
| Experiment | Magnetic Spectrum |
|---|---|
| Category | Tools |
| Used sensors | Magnetometer |
The experiment "Magnetic Spectrum" displays the frequency spectrum as well as the peak frequency of magnetometer data. You can choose the number of samples used for the spectrum. If you incease the number, the spectrum will have a higher resolution allowing for more precise frequencies. If you decrease the number, you will get faster responses to changes.
The maximum frequency in the spectrum is determined by the acquisition rate of the sensor (actually, it is half the acquisition rate). So, the spectrum will depend strongly on the device.
Requirements
There are no hardware requirements, except that your device needs a magnetometer.
Setup
There is no specific setup.
Analysis
This experiments records the magnetic field and keeps a history of the values. The Fourier transform is calculated over the last N samples, with N being chosen by the user. The peak frequency is the frequency of the maximum of the Fourier transform.
Problems and resolutions
- The frequency resolution is too low. The frequency resolution is limited by the length of the recording. By increasing the number of samples, you can increase the resolution, but this will also slow down the response to changes.
- The maximum frequency is too low. The maximum frequency is half the acquisition rate of the sensor (Nyquist frequency). So, the maximum frequency is a limitation of your device.
