Speed MeasurementSENSOR LINE's SPx fiber optic axle sensors are superior detectors for speed measuring purposes. Unlike piezo-electric axle sensors they are insensitive to shocks or vibrations of the roadway surface and respond only to the pressure of the tyres. In addition to that they deliver analogous output signals which can be cross-correlated to determine time delays with maximum precision.
Based on this principle earlier versions of CLASSAX incorporated SENSOR LINE's TKV speed measuring process. This has been discontinued because it required an additional axle sensor, whereas a traditional start-stop measurement between Sensors 1 and 2 delivers an accuracy far sufficient for AVC purposes. Likewise, its accuracy is also far sufficient for many other purposes where the requirements are defined by common sense. Moreover, CLASSAX incorporates a very sophisticated axle recognition method which avoids many failure modes that cause gross errors due to signal mapping problems.
Thus – depending from the actual application – using a CLASSAX system for speed measurement must well be considered as a competitive option, compared for example with enforcement systems. One must bear in mind that the accuracy of such systems is often achieved by discarding contradictory redundant measurements. Where this is not acceptable and a good overall accuracy is needed instead CLASSAX might clearly be the better choice.