Instruction Manual, Type 9195E - WIM
Instruction Manual, Type 9195E - WIM
Instruction Manual, Type 9195E - WIM
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Signal Processing<br />
5.2 Digitizing the analog signal<br />
U ~ F z U ~ F z<br />
≥12-bit ADC resolution over ±5 V volt range<br />
Analog anti-aliasing filter (before the ADC) with ≈600 Hz<br />
low-pass cutoff<br />
t t<br />
The sampling rate can be approximated by the following<br />
formula:<br />
Sampling rate =<br />
velocity (m/s) x min. of measured points<br />
footprint length<br />
The minimum of measured points means the minimum<br />
quantity of sampling points per signal, to approximate the<br />
original force signal without loosing information, it should<br />
never fall below 10 to 20, even under best conditions.<br />
Examples:<br />
Truck Tire<br />
velocity 80 km/h =<br />
22,2 m/s (50 mph)<br />
number of measured points per curve 20<br />
footprint length 0,4 m<br />
22,2 m/s x 20<br />
Sampling rate = = 1 111 Hz<br />
0,4 m<br />
High inflated car tire<br />
velocity 150 km/h =<br />
41,6 m/s (93 mph)<br />
number of measured points per curve 10<br />
footprint length 0,15 m<br />
41,6 m/s x 10<br />
Sampling rate = = 2 778 Hz<br />
0,15 m<br />
Practically: 2 000 preferred<br />
002-300e-07.04 (200-348e) Page 9
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