A method for locating and tracking communication units in a synchronous wireless communication system allows for system synchronization and communication unit location when usable GPS signals are not available or are being jammed. Communication units communicate within frames that are synchronized with a timing-reference signal. The timing-reference signal may be generated from GPS signals when available or generated from TOA and trajectory extrapolations when the GPS signals are not available. A disciplined oscillator may be used to maintain substantial synchronization over a few seconds of a frame. In one embodiment, propagation delays of received signals within the frame are determined and provided to other communication units allowing one or more communication units to calculate locations of the communication units. The location information may be reported to the other communication units for use in the self-synchronization.

 
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> Methods to support process quality and maintenance during control of an industrial process such as welding

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