absolute encoder！

An absolute encoder has many pulse tracks on its
transducer disk.
– When the disk of an absolute encoder rotates, several
pulse trains – equal in number to the tracks on the disk
– are generated simultaneously.

– At a given instant, the magnitude of each pulse signal
will have one of two signal levels (i.e., a binary state)
as determined by a level detector. This signal level
corresponds to a binary digit (0 or 1). Hence, the set of
pulse trains gives an encoded binary number at any
instant.
– The pulse windows on the tracks can be organized into
some pattern (code) so that each of these binary
numbers corresponds to the angular position of the
encoder disk at the time when the particular binary
number is detected.
– Pulse voltage can be made compatible with some form
of digital logic (e.g., TTL)
– Direct digital readout of an angular encoder position encoder is possible

–Absolute encoders are commonly used to measure
fractions of a revolution. However, complete
revolutions can be measured using an additional track
that generates an index pulse, as in the case of an
incremental encoder.

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