DataFFT
Extension
ExtensionDescription
Collects data from any OpenBCI board and calculate FFT.
Remember that FFT only analyse frequencies up to half of the current sample rate.
Class Methods
.new
create a new instance
Arguments:
| board |
an instance of a OpenBCI subclass (for example a CytonSerial or GanglionWifi). |
| fftSize |
the FFT window size. Should be a power-of-two. |
| windowType |
By default this will be Signal: fftCosTable. Use one of the following symbols to specify other types: |
Instance Methods
.board
get the board instance
.fft
perform FFT calculation.
Arguments:
| data |
an Array of data to be analysed. |
Returns:
the FFT data (magnitudes only) as an Array. The size of the array is half the fftSize + 1.
.fftSize
the FFT window size
.fftSize2
half the FFT window size
.bw
width of each frequency band in Hz. The first and last bands is half as large as this value.
.indexToFreq
convert from fft index to frequency (in Hz).
Arguments:
| index |
band index |
Returns:
a Float that is the middle frequency of the band.
.freqToIndex
convert from frequency (in Hz) to fft index.
Arguments:
| freq |
frequency |
Returns:
an Integer that is the index of the band that contains the requested frequency.
Examples
link::OpenBCI-SuperCollider/Classes/DataFFT::