Radio ranging using sequential time-difference-of-arrival estimation

An apparatus for determining a position of a target object, comprising the steps of:

• a first sensor configured to receive to a first signal of a pair of radio signals received from a target object;
• a second sensor configured to receive to a second signal of the pair of radio signals;
• means for applying repeatedly a window function while time shifting the window function during a correlation time interval to produce a first windowed signal and a second windowed signal for each application of the window function;
• means for cross-correlating each first windowed signal with each second windowed signal to determine a peak for each cross-correlation;
• means for comparing, sequentially in time, the peaks to a predetermined threshold to detect a first pulse in the first signal and a first pulse in the second signal, a delay between the first pulses indicative of a position of the target object;
• and
• means for outputting the position of the target.