FFT Mode

In the menu DISPLAY/FFT you can select:

  • FFT OFF: The tinyPFA is optimized for phase and frequency measurement and sending or recording phase data for evaluation by other programs such as TimeLab.
  • FFT PHASE: Disables all but one trace showing the FFT of the B-A phase. Settings are optimized for a wide frequency span in the FFT. Span can be reduced by increasing Tau to max 5 ms
  • FFT A: Disables all but one trace showing the FFT of the port A signal. Span is +/- 390Hz allowing a quick check on the presence of spurs. Span can be reduced by increasing Tau to max 5 ms
  • FFT B: Same as above but for the B input.
  • WIDE: Only applicable to the FFT A or B mode. Will increase the FFT span to +/- 37.5 kHz. Useful when there is a possible large frequency error.
  • AVERAGE: Enables a running average to smooth noise.
  • MAX AVER: Sets the maximum count of running averaging to be used

With FFT mode active, USB or SD card logging should not be used as there will be gaps in the data.

Disabling FFT mode may not work correctly, it is strongly suggested to restart the tinyPFA after being used in FFT mode.

Some examples of FFT mode:

Port A phase modulated with 100 Hz and 0.001 degrees phase deviation. The FFT PHASE spectrum can not distinguish between positive and negative phase modulation frequencies

Port A amplitude modulated with 50 Hz and 0.01 % depth. The FFT A spectrum can display both negative and positive frequencies. The white number displays the frequency of the strongest input signal

Port A input at 9.990 MHz. The displayed marker frequency still is a bit off. The big white number displays the set frequency.