Precision geolocation of moving or fixed transmitters using multiple observers

A method for estimating the location of a transmitter transmitting a signal having a wavelength λ, the method comprising:

• receiving a signal from the transmitter at a first receiver;
• receiving a signal from the transmitter at a second receiver;
• moving the second receiver with respect to the first receiver;
• comparing the signal received by the second receiver and the signal received by the first receiver;
• at a first time, determining a first phase difference between the signal received by the second receiver and the signal received by the first receiver;
• at a second time, determining a second phase difference between the signal received by the second receiver and the signal received by the first receiver;
• scaling the first phase difference and the second phase difference by λ resulting in a first and a second wavelength scaled phase difference measurement;
• subtracting the first wavelength scaled phase difference measurement from the second wavelength scaled phase difference measurement, resulting in a differenced wavelength scaled phase difference measurement, and
• determining, from the differenced wavelength scaled phase difference measurement, that the transmitter lies on a hyperboloid having a first focus at the location of the second receiver at the first time, and a second focus at the location of the second receiver at the second time.