Frequency Selective Characteristic Values - FAG Detector III User Manual

7.2 Frequency selective characteristic values

For characteristic values designated by the "sel" code, you can define a frequency
band within a range. This is used for the value calculation.
In Trendline the low pass cutoff frequency up to which measurements are to be
taken is defined for each channel. The sampling rate is always 2.56 times the
value of this cutoff frequency. The time signal that is recorded in this way is used
to calculate a frequency spectrum by means of an FFT calculation. This is then
used to recalculate the characteristic values within the defined limits. An a
value of between 2 kHz and 5 kHz is therefore calculated for a low pass filter
setting of 5 kHz, for example.
Characteristic value Analog channel
a
eff
a
sel
ISO 10816
v
sel
d
eff
d
sel
The low pass and FFT length can be adjusted for each channel. Both of these
factors affect the sampling rate, the minimum possible frequency and frequency
resolution.
Lowpass Sampling
rate
200 Hz 512 SPS
200 Hz 512 SPS
500 Hz 1.28 kSPS
500 Hz 1.28 kSPS
1 kHz 2.56 kSPS
1 kHz 2.56 kSPS
2 kHz 5.12 kSPS
270
Acceleration
Acceleration
Speed
Speed
Demodulation
Demodulation
FFT-length
1600 lines 0.125 Hz
3200 lines 0.1 Hz
1600 lines 0.3125 Hz 0.94 Hz
3200 lines 0.156 Hz
1600 lines 0.625 Hz
3200 lines 0.3125 Hz 0.94 Hz
1600 lines 1.25 Hz
Frequency range
2 kHz - low pass acceleration channel
f - low pass a (both frequencies adjustable,
min_a
see table below )
10 Hz - 1 kHz
f - low pass v elocity channel (both frequencies
min_v
adjustable, see table below )
f - low pass demodulation channel
min
f - low pass demodulation channel (both
min
frequencies adjustable, see table below )
f f (*
271
min min_v
0.375 Hz
0.19 Hz
0.47 Hz
1.875 Hz
3.75 Hz
) Frequency resolution
0.125 Hz
0.0625 Hz
0.3125 Hz
0.156 Hz
0.625 Hz
0.3125 Hz
1.25 Hz
eff