Messtechnik Sachs Irinos IR, User Manual

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Irinos IR Users Manual © 2015 - 2016 Messtechnik Sachs GmbH, Germany
Application notes
considered in the measurement process (e.g. by referencing while
moving).
11.1.3
Interpolation (only 1Vpp)
An incremental encoder with 1 Vpp - Interface provides two sine
waves, each as a differential output signal. The phase shift between
these is 90°. One signal period (i.e. 360°) relates to one incremental
division of the encoder. The Irinos-Box
IR-INC separates a
division into 200 incremental steps via analogue interpolation.
Thereby the usable resolution of the encoder increases by 200.
Example: An incremental encoder has a resolution of 1.800
divisions/revolution. Via the interpolation, this results in
1.800 divisions/revolution * 200 increments/division = 360.000
increments/revolution.
1Vpp signal period
The accuracy and reliability of the interpolations depends on the
quality of the differential sine signals. An ideal signal has the following
characteristics:
o
The differential voltage is 1 Vpp.
o
The signal offset is 0, i.e. at 0° the signal always provides the
same value.
o
The phase shift between both sine signals is exactly 90°.
In reality, such a signal is rarely available. Because of this, the Irinos-
Box
IR-INC has an integrated gain- and offset control (patent
applies). It corrects these deviations within the allowed value range
(see limiting values in the specification section of the datasheet).
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