US Patent 7676205 Active receiver detection and ranging

Method (500) and system (402) for actively detecting and determining a range of a remotely located radio receiver (100). The invention also provides a method and system to determine whether a remote receiver (100) is receiving a transmitted signal (418) and the minimum necessary transmitter power required to establish a communication link to the receiver (100). Finally, the invention also provides a method and system to resolve directional ambiguities due to multipath.