Patent ID: 8027590

Claim:
A system comprising: a transmitter and receiver, the transmitter being configured to transmit an electromagnetic signal to the receiver at each of one or more selectable frequencies, the receiver being configured to receive the electromagnetic signal and another electromagnetic signal for mixing therewith, system including a first propagation path of the electromagnetic signal to the transmitter, and a second propagation path of the other electromagnetic signal to the receiver; an arrangement located along either of the first or second propagation paths, or along each of the first and second propagation paths, the arrangement configured to alter the length of a respective propagation path such that the difference of the lengths of the first and second propagation paths is altered at a pre-selected rate during transmission of the electromagnetic signal from the transmitter to the receiver, and receipt of the electromagnetic signal and the other electromagnetic signal at the receiver; and a processor configured to recover an amplitude and phase of the transmitted electromagnetic signal, including being configured to receive a sequence of samples of the received electromagnetic signal, and Discrete Fourier Transformation process the sequence of samples.