Abstract: A method for determining a location of a wireless transmitting device transmitting a digitally modulated transmitted radio frequency signal. The method comprises, at spaced-apart receivers: generating a received radio frequency signal and including time tags therein responsive to the transmitted radio frequency signal, detecting a destination message signal responsive to the received radio frequency signal, comparing the destination message signal and the received radio frequency signal and determining a time of arrival of the destination message signal responsive to the step of comparing and responsive to the time tags. The method further comprises determining a pairwise time difference of arrival of the received radio frequency signal for two pairs of receivers and determining the location of the device responsive to the pairwise time difference of arrival.

Abstract: A method of detecting and correcting bit errors in a digitally encoded data stream includes correlating a received bit transition in the data stream with a multitude of possible bit transitions to generate corresponding correlated bit transition values. A bit transition decision corresponding to a greatest correlated bit transition value is then generated for the received bit transition. Consecutive bit transition decisions generated for the data stream are compared to identify bit transition decision errors. Respective bit transition decisions are examined to determine if each decision is consistent with a prior adjacent bit transition decision in the data stream. If a bit transition decision error is identified, then the next greatest correlated bit transition decision is substituted for the bit transition decision in error.

Abstract: A method for determining a location of a digital radio transmitter includes detecting, by at least three spatially separated receivers, a digitally encoded radio signal, having a known pattern of bit transitions, radiated from the transmitter. Once detected, a time of arrival of the bit transitions at each of the receivers is determined. Then, an indication of the time of arrival at each respective receiver for the bit transitions is transmitted from each of the receivers to a central processor. At the central processor, time of arrival differences of common bit transitions among the receivers are determined. Based on the time of arrival differences, the central processor may calculate the location of the transmitter.