Speed sensor comprising a costas loop

Abstract

Speed sensor comprising at least one sensor element (1) and an analog-to-digital converter (2) that digitizes the output signals of the senor element / s, further comprising a Costas loop unit (3, 4, 5) that is connected to the output of the analog-to-digital converter (2).

Description

technical field [0001] The invention relates to a speed sensor according to the preamble of claim 1 and to the use of said sensor in a motor vehicle. Background technique [0002] The measurement of rotational velocity required in many fields of machines and systems is physically equivalent to the measurement of angular velocity. Generally, the rotational speed of the shaft is measured by applying a periodic pattern known as an "encoder" (eg, gear) around the circumference of the shaft, which is sensed by a sensor mounted at a fixed location other than the shaft. The sensor is able to distinguish between teeth and tooth gaps (or other periodically changing characteristics such as magnetic field direction or optical transparency). The sensor then produces an output signal that has the same periodicity as the sensed pattern. [0003] Sensors of this type output different signals depending on the signal processing present: there is an approximately sinusoidal signal, usually ...

AI Technical Summary

Problems solved by technology

Since the counting frequency only provides the average value of the frequencies in the measurement interval, the bandwidth of the measurement is also limited

[0007] In particular, when using square wave signals which are common in some applications, e.g. in automobiles, the accuracy is limited by the noise

Unlike a sinusoidal signal, for which at least some of the noise is away from the frequency band of the sinusoid and thus can be filtered, a square wave signal offers no opportunity for spectral separation of the components

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