Patent ID: 8265488

Claim:
An electromagnetic transmission and reception system, comprising, a transmitter section and a receiver section, wherein the transmitter section comprises: a first signal source; a second signal source at a significantly lower frequency than the first signal source; a comb generator for generating from the first and second signal sources a plurality of signals simultaneously with fixed frequency spacing between adjacent pairs of the comb line signals, wherein there is a plurality of adjacent pairs of comb line signals, and the fixed frequency spacing is derived from the second signal source frequency; means for selecting one or more pairs of the plurality of signals; and for the or each pair, means for combining the signals of the pair to derive an output signal having a frequency derived from the difference between the frequencies of the signals of the pair, and wherein the receiver section comprises: means for combining a received signal, which comprises a received version of the output signal, with a local oscillator signal for frequency down-conversion of the received signal, wherein the local oscillator signal is generated by the transmitter section.