In the PSV 300-H, low pass filters with 8th order Butterworth characteristicsIn the PSV 300-H, low pass filters with 8th order Butterworth characteristics
are used. Multiples of 0.4kHz up to a maximum of 102.4are used. Multiples of 0.4kHz up to a maximum of 102.4kHz can be selectedkHz can be selected
for the cutoff frequency. The amplitude error in the pass band can be roughlyfor the cutoff frequency. The amplitude error in the pass band can be roughly
estimated as follows:estimated as follows:
Up to 75% of the cutoff frequency, the maximum amplitude error isUp to 75% of the cutoff frequency, the maximum amplitude error is ±±1%.1%.
At the cutoff frequency, the amplitude error isAt the cutoff frequency, the amplitude error is
−−
3dB (approx.3dB (approx.
−−
30%).30%).
The phase shift increases with the frequency as The phase shift increases with the frequency as shown inshown infi
figugurere 4.4.33. Up to. Up to
approximately 50% of the cutoff frequency the phase shift increasesapproximately 50% of the cutoff frequency the phase shift increases
proportionally to the frequency.proportionally to the frequency.
The complete amplitude frequency response of an The complete amplitude frequency response of an 8th order Butterworth low8th order Butterworth low
pass filter is shown inpass filter is shown infi
figugurere 4.4.11. The frequency is . The frequency is normalized to the cutoffnormalized to the cutoff
frequency ffrequency f
cc
..
Figure 4.1: Amplitude frequency response of an 8th order Butterworth low pass filterFigure 4.1: Amplitude frequency response of an 8th order Butterworth low pass filter
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