Patent ID: 8891639

Claim:
A system for determining a representation of a multi-tone signal, said system comprising: an input for applying said multi-tone signal that includes a plurality of phase-coherent tones, at least two of said plurality of phase-coherent tones being modulated according to respective modulation signals; phase-coherent mixing means for demodulation in connection with data acquisition means for digitization, wherein said mixing means and data acquisition means are arranged to be fed with said multi-tone signal and with a reference signal that includes said plurality of phase-coherent tones, each pair of phase-coherent tones having a fixed phase difference, wherein said data acquisition means is arranged to be triggered by a trigger signal yielding a representation of said modulation signals with fixed delay; and processing means arranged to receive digital signals output from said data acquisition means and to compare phase information of a downconverted tone of said multi-tone signal after demodulation with phase information derived from the corresponding tone of said reference signal after demodulation, and further arranged to control said phase-coherent mixing means for sequential downconversion, thereby enabling representation of said multi-tone signal, wherein said comparing includes a phase normalization.