30: Free Windows; Special Parameters, Display; 40: Frequency Weighting Function; 41: Frequency Transient Shift, E - BRUEL & KJAER 2032 Instruction Manual

12.5.12. 30: Free Windows
If set to 1, Special Parameter 30 allows real-time display in Spectrum Averaging of the
Transient and Exponential Weighting functions, irrespective of the setting of the RE-
CORD controls, (see Section 9.12).
12.6. SPECIAL PARAMETERS, DISPLAY
12.6.1. 40: Frequency Weighting Function
Special Parameter 40 specifies the weighting function applied to the Auto Spectrum,
Cross Spectrum, or Frequency Response Function when calculating Autocorrelation,
Cross Correlation, or Impulse Response. The Parameter can be set from 0 to 6
0: Rectangular, (no weighting)
1: Hanning
2: Transient
3: Exponential
4: Flat Top
5: Kaiser Bessel
6: User-defined
If Transient Weighting is selected, the weighting function is defined using Special Pa-
rameters 41 to 44. If Exponential Weighting is selected, the weighting function is de-
fined using Special Parameters 41 and 42. If a User-defined Weighting is selected, the
coefficients for the weighting function are entered using Special Parameters 41 to 46.
The User-defined Weighting function is then as follows:
2E [ ( 2
7r ) (
2
7r )
W(k)
=
A
0
-A
1
cos n -
+
A
2
cos 2n-
32768 N N
0~
n
~
N-1
N
=
1024 in Dual Spectrum Averaging mode
N
=
2048 in Signal Enhancement mode
12.6.2. 41: Frequency Transient Shift, E
Defines the shift in number of frequency elements for Frequency Transient Weighting
or
Defines the Shift in number of frequency elements for Frequency Exponential Weight-
ing
or
Defines the coefficient E for Frequency User-defined Weighting.
137