Patent ID: 8319680

Claim:
A method for accurately determining a level of a liquid, the method comprising: emitting radar signals towards the liquid, the emitted radar signals having multiple frequencies and multiple first phases; receiving radar signals reflected from the liquid, the reflected radar signals having the multiple frequencies and multiple second phases; determining multiple phase differences between the emitted radar signals and the reflected radar signals; and deriving the level of the liquid based on an actual phase difference between the emitted radar signal having a first frequency and the reflected radar signal having the first frequency; wherein the actual phase difference is determined based on a measured phase difference between the emitted radar signal having the first frequency and the reflected radar signal having the first frequency; and wherein the measured phase difference is adjusted using a wrapping factor determined by: deriving a second level value based on a phase shift between phase differences associated with successively emitted and received radar signals having different frequencies; and deriving a value of the wrapping factor based on the second level value.