The present invention provides methods for a high-resolution active RTLS tag location determination system that provides for <1 ns TOA accuracy and resolution and significantly reduces the channel effects of multipath interference, even in low SNR applications. To accomplish these objectives, the present invention provides for an iterative and adaptive windowing function in each of the receivers of a receiver grid that captures multiple reflections of multiple transmissions from each of the associated target RTLS tags. The adaptive windowing function is used in conjunction with an asynchronous transmit and receive clock function that effectively increases resolution of TOA detection to levels less than the minimum detection window width associated with each of the receivers in the receiver grid.