Highly accurate RE-ID positioning system

Abstract

A balanced receive antenna circuit configuration determines an accurate position of a transponder within the antenna field pattern of the reader antenna. The balanced receive antenna configuration consists of two antennas physically rotated 90 degrees relative to one another, disposed concentrically on top of one another. Furthermore, each receive antenna consists of two coils located a predetermined distance apart. The optimum distance separating the coils is determined by trading off zero position detection with the transponder detection range. The transmitter antenna surrounds the receiver coilset. In operation, initially the transmitter antenna sends a power burst signal for a predetermined duration to charge up the transponder to the maximum charge possible. Then for a very brief duration, the transmitter antenna is damped to permit the receive antennas to better receive the transponder response telegram. Then simultaneously, one receive antenna receives the `X` position component and the other receiver antenna receives the `Y` position component in the form of voltages. Depending upon which quadrant of the antenna pattern the transponder is disposed, the sign and value of the X component and the Y component of voltage is detected. These voltages are then narrow band filtered around a center frequency and gated for a small portion of the length of the entire response telegram, and those outputs are combined in a signal processor which outputs the exact position data information.

Dependencies are inferred from the claim text.