Svantek SVAN 977A - Page 185

185
SVAN 977A User Manual - Appendixes
Table B.1.19 Header of the FFT analysis
Word
number
Name
Comment
0
0x0051
[51 = id, 00 = block’s length in the second word]
1
BlockLength
block length
2
0x0101
[used_profile, profile’s mask]
3
reserved
4
Zoom
zoom flag
5..6
CentralFreq
central frequency in [mHz] (in case of Zoom = 1)
7..8
FreqResM
frequency resolution (integer mantissa)
9
FreqResExp2
frequency resolution (binary exponent)
note: frequency resolution is calculated from the formula:
∆F[Hz] = FreqResM * 2
FreqResExp2
10
N
number of FFT spectrum lines
11
T
number of TOTAL values
12
Band
band of the FFT analysis (values in hertz are approximate):
0 – 40 kHz,
1 – 20 kHz,
2 – 10 kHz,
3 – 5 kHz,
4 – 2.5 kHz,
5 – 1.25 kHz,
6 – 625 Hz,
7 – 312 Hz,
8 – 156 Hz,
9 – 78 Hz
13
Screen
screen function:
0 – HANNING,
1 – RECTANGLE,
2 – FLAT TOP,
3 – KAISER–BESSEL
14
ScreenFactor
screen correction factor (in 0.01dB)
15
Averaging
type of averaging:
0 – LINEAR
1 – EXPONENTIAL
16
TimeConst
time constant in [ms] (in case of Averaging = 1)
17
Filter
filter:
0 – HP,
1 – Z,
2 – A,
3 – C,
5 – B
18
InstFreq
instantaneous FFT spectrum frequency in [Hz]
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