Fast Fourier Transform (Fft) - Phonic PAA6 Manual Del Usuario

Fast Fourier Transform (FFT)

The FFT function is, in essence, an RTA with much finer resolution and slightly slower refresh rate. Use
the FFT analyzer to check the frequency response of sound systems and listening rooms as you adjust
your speaker positions, room treatments and equalizer settings. Continuously monitor results as you
correct these problems for updates on whether the situation has improved or not.
Like the RTA function, measurements can be taken at any weighting, with various other possible settings
available. A frequency range as wide as 0.2 Hz to 20 kHz can be monitored using the FFT function.
Taking FFT measurements:
1. Position the PAA6's microphone in an appropriate position. This usually means somewhere pointing
at the ceiling, preferably directed away from all loudspeakers in your setup.
2. Set the frequency range that best suits your needs. The following are the selectable frequency
ranges:
0.2 Hz – 78.2 Hz 0.4 Hz – 156.3 Hz
2.0 Hz – 834.0 Hz 3.9 Hz – 1.6 kHz
9.4 Hz – 4.0 kHz 11.7 Hz – 5.0 kHz
46.9 Hz – 20 kHz
3. Set the 'weighting' of the FFT. The most common weighting for many applications is flat (ie. no
weighting). (figure 33)
4. Also set the response time, and turn the peak hold and frequency detect on or off as required. (figure
33)
5. Run pink noise through your system. Whether the pink noise comes from the built in signal generator
or a test tone CD is not important.
6. Push the "RUN/STOP" button. Push the "RUN/STOP" button again at any time to pause the FFT.
PAA6
0.7 Hz – 312.7 Hz 1.5 Hz – 625.5 Hz
4.7 Hz – 2.0 kHz 7.8 Hz – 3.3 kHz
15.6 Hz – 6.6 kHz 23.4 Hz – 10 kHz
figure 33
23