A&D RA3100 Omniace Instruction Manual page 132

10. 10Appendix - 10.4. FFT Analysis
Transfer Function (Two Signal Analysis)
The transfer function indicates the frequency characteristics of the input and output of the transfer
system.
It is derived as the ratio of the cross power spectrum Gyx and input (reference) power spectrum Gxx.
Transfer function = Hyx = Gyx/ Gxx
Real number part
Imaginary number part
Amplitude
Logarithmic amplitude
Phase
Coherence Function (Two Signal Analysis)
Expresses a comparison of the power caused by the input signal of the transfer system and the total
output power. It is derived from the cross power spectrum Gyx, input (reference) power spectrum Gxx,
and output (comparison) power spectrum Gyy.
Amplitude
NOTE
The coherence function equals 1 across the entire frequency with a single measurement. Make sure to
perform averaging of the frequency axis.
Octave Analysis
1/1 octave band or 1/3 octave band analysis can be performed.
This product derives the power spectrum first and then adds the data in each band range.
Amplitude
Logarithmic amplitude
k1: Window function BW compensation coefficient
Rectangular
Hanning
Hamming
Lin-Rel
Lin-Img
Lin-Amp
Log-Amp
Phase
Lin-Amp
Lin-Amp
Log-Amp
1
0.666
0.731
HRyx
HIyx
�����������������
+ ����������������
2 2
10 × log(HRyx + HIyx
2
tan (HIyx/HRyx)
−1
| ������������ |
/(Gxx × Gyy)
2
Oct x k1
10 x log(Oct x k1)
132
)
2
1WMPD4004444