| 摘要 |
PURPOSE: To provide an electric wave detecting system, which follows up a target in semiconductor manufacturing equipment, for a multipass environment. CONSTITUTION: Receiver arrays 20, each of which is connected to a system processor 40 via a LAN, are distributed in a follow up area. By means of a TAG transmitter 30 arranged in each target, a spectral diffusion TAG transmission containing a unique TAG at least is sent at a selected interval. For a high resolution embodiment a target is oriented on the basis of an arrival time (TOA) difference, and each receiver includes a TOA trigger circuit, which is triggered on an arrival of the TAG transmission, and a time base latching circuit, which latches a TOA count from a 800MHz time base counter. For a low resolution embodiment, a specific position area is allocated in each receiver in the array, and the TAG transmission is received solely from the TAG arranged in the area, so that an arrival time circuit is dispensable.
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