A method of operating a plasma arc torch system includes placing a work piece to be cut on a table of the plasma arc torch system, wherein at least a portion of the work piece has a planer surface facing away from the table. The multiuser receiver is compatible with ZF-BLE, MMSE, decorrelating detectors and the like using Cholesky decomposition to minimize numeric operations. An n-type photodiode region is formed in the p-type region connected to the connection region.