I have some Odometry data taken from a Volkswagen Passat which gives the position. This is calculated using wheel ticks and in addition, I also have data which gives me the number of wheel impulses at each wheel. But unfortunately, I'm confused as to what they actually are. My question is, what are wheel ticks and wheel impulses?

I wasn't able to get much information online other than a whole set of references to wheel speed sensors and hence, posting on this site. Does that mean, wheel impulses give the wheel speed? (rpm)

1 Answer 1


A wheel speed sensor doesn't actually detect wheel speed. It just counts the notches on a toothed ring as it rotates. The brake computer interprets the data from the wheel speed sensor and uses it for the ABS, stability control and traction control and speedometer. The sensor itself doesn't calculate anything. If it's a "passive" sensor it just sends an analog voltage to the brake computer. If it's a passive sensor, it sends a square wave that the computer sees as a digital signal

  • Can we then say, that these notches counted by the sensor as the wheel rotates are the wheel impulses/ wheel ticks given to the brake computer? (Where, the brake computes counts the number of pulses/ reads the analog signal and uses this information to compute wheel speed)
    – surajr
    Sep 12, 2019 at 9:25
  • Yes, that's correct. See this post that shows the sensor, notched ring and brake controller. ricksfreeautorepairadvice.com/abs-abs-brakes
    – user9181
    Sep 12, 2019 at 16:21

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