Enhancing the Bit Density and Capacity in Hybrid Time/Phase Domain Electromagnetic Encoders

This paper presents an electromagnetic encoder exhibiting 8 bits per encoder position (or row) that can be read by means of a simple reader, i.e., a pair of independent and aligned one-port transmission lines terminated with a matched load and fed with a single-tone (harmonic) signal. Encoder positions (identified by a unique ID code) are read sequentially by displacing it over the reader, and phase encoding is the considered approach. Thus, the encoders consist of two chains of inclusions (electric-LC –ELC– resonators) located at the same axial (periodic) positions in the chains, but at different transverse positions. When the chains cross the reader lines, the ELCs generate different phases in the reflection coefficients of the lines, depending on their transverse position. Thus, the number of different states per encoder position is dictated by the square of the number of different phases (or transverse positions) per chain. In the reported prototype, 16 transverse positions per chain are considered, corresponding to a total of 256 states and 8 bits per encoder row. This data capacity per encoder position is very competitive and can be useful for the implementation of absolute electromagnetic encoders, where a unique ID code is assigned to each encoder position.