12 | Analog and Frequency Inputs
90/148 DDU 9 Bosch Motorsport
12.2.5 Digital filter details
DDU 9 uses A/D converter oversampling and digital filtering to recording rate.
Digital filters eliminate ‘out-of-band’ noise
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
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