I thought I'd dig out my scope and look in more detail at the action of the smoothing circuit on the suspension height sensor.
The circuit:
Cost - just a few dollars. Note the adjustment pot (1 meg) that allows the smoothing time to be set. For this test I wired into place an additional pot so that I could alter the input voltage just by turning a knob.
On the scope pics the blue trace shows the input signal and the red trace, the output signal. The vertical scale is 2V per division and the horizontal scale, 5 seconds per division
Scope pic 1.
You can see that at the 5 second mark I abruptly decreased the input voltage. You can then see it took about 7 seconds for the output to settle at the new level ie this pot position gave about a 7 second smoothing time. You can also see how the quick fluctuations are completely damped out.
Scope pic 2
In this one I have reduced the smoothing time. Note how now it takes a shorter time for the output to follow the input (about 3-4 seconds) and how the quick fluctuations are now not completely smoothed.
The circuit values can give a smoothing time from 0 to about 15 seconds. In use you set the smoothing pot so that at a constant speed, flat and straight road, the values settles to consistent and readable value within a reasonable time.