Cut‐off frequency automatically adjusted to recording rate
Example:
▪ 100 Hz recording rate (10 ms)
▪ < 40 Hz pass band (> 99 %)
▪ 50 Hz stop band (< 1 %)
Linear phase – no signal distortion
0
500
1000
1500
2000
2500
3000
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
Abtastwerte (roh)
Wert
10000Hz Abtastrate
0
5
10
15
20
25
30
-1.5
-1
-0.5
0
0.5
1
1.5
Abtastwerte (gefiltert)
Wert
100Hz Abtastrate
0
5
10
15
20
25
30
-1.5
-1
-0.5
0
0.5
1
1.5
Abtastwerte (dezimiert)
Wert
100Hz Abtastrate
Sensor signal with noise
Recorded signal 100Hz
(unfiltered)
Recorded signal 100Hz
(filtered)
Latency compensation – no filter delay in recorded data
▪ Filtering is (smart) averaging over several samples
▪ Filtered signal is delayed with respect to real time signal
▪ DDU 8 filters have constant, frequency independent delay
▪ Delay (e.g. 22 samples at 10 ms) is corrected during recording
▪ No delay filtered vs. unfiltered in recorded data
▪ Correction is (of course) not possible for real time data (display, online, PWM
out)
▪ Use filtered data for recording, use unfiltered data for real‐time
Configuring a frequency input
This function requires the installation of Software Upgrade 2.
Example: measurement of wheel speed
▪ Pulse wheel attached to wheel
▪ Each passing tooth of pulse wheel triggers hall sensor
▪ Calculation of wheel speed with wheel circumference
10.3.6
Analog and Frequency Inputs | 10
Bosch Motorsport
DDU 8 Manual
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