Patent ID: 8340686
Filing Date: 2012-12-25
Classification: G01S

Abstract:
1. A method of determining a relative range, relative velocity of motion, clock frequency offset, clock phase offset or time reference of a first device with respect to a second device, the method comprising: sending a first reference signal from said first device to said second device at a first time, wherein said first reference signal has a frequency and phase determined by a first reference clock of said first device; receiving at said first device a second reference signal sent from said second device at a second time, wherein said second reference signal has a frequency and phase determined by a second reference clock of said second device; determining a phase of said second reference signal with respect to said first reference clock and determining a frequency of said second reference signal; receiving from said second device measurement data, said measurement data comprising data from a determination of a phase of said first reference signal with respect to said second reference clock and from a determination of a frequency of said second reference signal at said second device; determining at least one of said relative range, relative velocity of motion, clock frequency offset, clock phase offset or time reference of said first device with respect to said second device by determining a substantially self-consistent solution to at least one equation of a set of equations of the form: where wherein said first and second reference clocks are unsynchronised with one another, and wherein said determining of said substantially constant solution comprises compensating for a said phase and frequency offset between said first and second reference clocks such that a frequency offset and changing phase one of said unsynchronised reference clocks is characterised with respect to the other of said reference clocks by said parameters θ(t