System and method for enhanced point-to-point direction finding

A method of determining a range between a first unit and a second unit using a chirp signal, the first unit including a first transmitter, a first receiver and a first processor and the second unit including a second transmitter, a second receiver and a second processor, the method comprising:

• transmitting a control signal and a first signal from a first unit to a second unit with the first transmitter, wherein there is a time base difference between the first unit and the second unit and the control signal time synchronizes the second unit to the first unit such that the time base difference is bounded;
• receiving the first signal at the second unit with the second receiver;
• converting the first signal to a second signal with the second receiver;
• determine with the second unit a first sum of a trip delay and the time base difference between the first and the second unit with the second processor based on a frequency ramp of the first signal, propagation speed of the first signal, the frequency of the second signal, and an intermediate frequency used by the second receiver;
• and
• transmit a third signal to the first unit with the second transmitter;
• receive and convert a second transmitted signal comprising at least the third signal to a fourth signal with the first receiver;
• determine a second sum of the trip delay and a negative value of the time base difference between the first and the second unit with the first processor based on a frequency ramp of the third signal, propagation speed of the third signal, the frequency of the fourth signal, and an intermediate frequency used by the first receiver;
• receive the value of the first sum with the first receiver from the second unit and determine the trip delay with the first processor based on the first sum and the second sum;
• and
• determine the range between the first unit and the second unit with the first processor based on the trip delay and the propagation speed of the first and third signals;
• wherein both the first signal and the third signal comprise at least one chirp signal that changes in frequency over the period of the chirp signal.

A method of overcoming multi-path effects, the method comprising:

• receiving a received signal at a second unit, wherein the received signal is the sum of a transmitted signal transmitted from a first unit and one or more reflections of the transmitted signal;
• converting the received signal to a converted signal with a receiver of the second unit;
• determining the lowest frequency component or lowest phase component of the converted signal;
• and
• determining the distance between the first unit and the second unit based on the lowest frequency component or the lowest phase component of the converted signal.

A method of determining a bearing between two or more units in a reflective or non-reflective environment, the method comprising:

• receiving a first signal from a first unit at three or more antennas of a second unit such that the second unit inputs a received signal for each of the antennas;
• determining the lowest frequency component of each of the received signals;
• calculating the phase of the lowest frequency component of each of the received signals;
• and
• determining the bearing between the first unit and the second unit based on two or more different pairs of the phases calculated.