Polytec OFV-511 - Page 38

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The phase frequency response of the filter is shown in figure 4.5.
An additional time delay is caused by the velocity decoder. It depends on both
velocity decoder and velocity measurement range and is approximately a few
microseconds. The resulting overall phase shift ∆Φ can be estimated using
the following simple equation:
Equation 4.3
(refer to section 7.1.4)
Figure 4.5: Phase frequency response of a 3rd order Bessel low pass filter in the passband
-1 0 0
-8 0
-6 0
-4 0
-2 0
0
0.0 0.2 0.4 0.6 0.8 1.0
Phase / degrees
f
f
C
∆Φ 100°
f
f
c
---
p
d
f⋅
+
⋅
=
f…frequency in kHz
f
c
…cutoff frequency of the low pass filter in kHz
p
d
…specific phase roll-off