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Optical encoder- SEI

US-Digital make a range of encoders that make use of optical methodology. The A2 and A2T are examples of these. To interface to a computer US-Digital manufacture a SEI to RS232 Adapter known as the AD2-B.


Here is their website outlining the system http://www.usdigital.com/products/ad2b/index.shtml


The system described here uses an A2 (Non contacting optical rotary position sensor from US-Digital) for azimuth and an A2T (single axis digital gravity angle sensor from US-Digital) for elevation. The AD2-B does the interfacing into the Shack Unit. It provides a readout in 0.1 degree steps for Azimuth (0-360.0 degrees) and 0.1 degree steps (-180.00 through to 0.0 and to +180.00).




This solution requires the setting of a flag in the Shack Unit. This is menu item 35 and is to be set to SEI. The attached manual explains in more detail how it all works.


As with all the other encoder solutions this approach continues to work with either the PIC generating moon/sun data and controlling the relays or the computer generating the data with VK3UM's EMEPlanner or with Orbitron for satellite work.


Using any Gray Coded Optical Encoder


Click here to access a page showing how to use a 10, 12, 14 or 16 bit Gray Coded optical encoder with the VK5DJ Beam Indicator

AD2-B and A2/A2T encoders in Doug VK3UM's shack in preparation for putting the encoder on his EME dish.

From left: A2T elevation, AD2-B serial interface, A2 azimuth.