Specifications

Phase Method Decoder
(A block diagram of a typical Phase Method Decoder is shown in
figure 4.)
The principle of operation is based on the fact that the phase
difference between reference voltage and the voltage induced
in the rotor is a direct measure of the shaft position. The stator
windings are excited by two 90° phase-shifted voltages generat-
ed by a sine/cosine generator. The counter is preset to zero at
zero crossing of the reference voltage and latched at zero cross-
ing of the rotor voltage, and the difference between preset and
latch gives the shaft angle. The phase method decoders do not
have the environmental immunity of the ratiometric convert-
ers. The trade-off is the relatively lesser cost of the phase
method decoders.
The output of R/D converters can be offset, displayed and
synchronized to interface with programmable controllers.
The ratiometric decoder, though hooked-up to a simple single-
turn resolver, can be programmed to operate in single-turn or
multi-turn mode. Simple front panel set-up of counts per turn
eliminates any mechanical gear trains. With program stored in
non-volatile EEROM memory, it is presettable, prescalable,
and still absolute (over half a turn). Parallel BCD output with
built-in PC-Handshake and serial link facilitates direct inter-
face to programmable controllers and computers.
A-5
800-TEC-ENGR
www.avg.net
Position Transducers/Sensors
SECTION
A
(Figure 3)