Abstract: A secure data transmission system and method for targeting specific receiver locations. The secure data transmission system includes a time multiplexer, a time delay unit, a receiver tacker, and a plurality of transmitters. Additionally, the secure data transmission system may include a multiplexing sequence, a digital switch, a plurality of empty vectors, a range calculator, a delay estimator, and a plurality of stream time delays. The method for targeting specific receiver location includes receiving an input data stream, multiplexing the input data steam, receiving at least one instantaneous receiver locations, calculating a plurality of transmission ranges for each of the plurality of output data streams, calculating a plurality of time delays for each of the plurality of output data streams, delaying each of the plurality of output data streams according its calculated time delay, and transmitting each of the plurality of output data streams.

Abstract: An apparatus for passive coherent location includes a forecaster, an evaluator, a receiver, and a correlator. The forecaster generates a prediction of a radio-frequency signal transmitted from an antenna of a broadcasting service. The evaluator generates an effectiveness metric from the prediction of the radio-frequency signal. The receiver receives the radio-frequency signal that an object reflects from the antenna to the receiver. The correlator determines, from the radio-frequency signal reflected from the object as received at the receiver, an ambiguity function having a maximum at a temporal offset and a Doppler shift. The temporal offset and the Doppler shift at the maximum partially determine at least a position of the object. The apparatus optionally includes a selector for tuning the receiver to the radio-frequency signal in response to the effectiveness metric.