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MultiCam Boards Documentation > MultiCam Documentation > MultiCam User Guide > The Channel Class > Understanding the Rate Converter > How to Use an Encoder? > Encoder Characteristics

Encoder Characteristics

An encoder is an electro-mechanical device aimed at delivering a measurement of the web speed.

Usually this device is attached to the rotational axis of one of the rolls transporting the web.

The speed measurement is made known thanks to a pulse train the frequency of which is proportional to the speed.

When the web is traveling in the axial direction at some given speed, the pulses provided by the encoder exhibit a predictable frequency.

We will characterize the encoder operation with a value called the "encoder pitch".

The encoder pitch is simply the distance traveled by the web between two successive pulses provided by the encoder. This distance is not a function of the web speed.

The frequency of the pulses delivered by the encoder while the web is moving will be called the encoder rate. The encoder rate obviously varies with the web speed. The following applies:

Consider that an encoder is provided with an encoder pitch of 0.75 mm.

If the transport mechanical system moves the web at 50 cm/s, the encoder generates a pulse train with a frequency of 667 Hz.