Systems and methods of using IQ modulation for calibration or measurement

A method for generating a signal to facilitate frequency analysis, comprising:

• generating a plurality of discrete tones according to a frequency spacing and a frequency offset to produce a comb spectrum, wherein the frequency offset is a fraction of the frequency spacing;
• modulating said plurality of discrete tones to generate a modulated signal, wherein said modulating generates a respective spectrally inverted spur for each of said plurality of discrete tones, and wherein said frequency spacing and said frequency offset cause said spectrally inverted spurs to occur at frequencies other than frequencies of said modulated signal that are associated with said plurality of discrete tones;
• communicating said modulated signal through a channel;
• analyzing said modulated signal after communication through said channel to generate a frequency representation;
• and
• creating an estimated frequency response of said channel by excluding frequencies of said frequency representation that are associated with said spectrally inverted spurs;
• wherein said frequency spacing is ωp, said frequency offset is an integer multiple of ωp/N, and N is an integer;
• and
• wherein said analyzing said modulated signal utilizes a Discrete Fourier Transform (DFT) that possesses a frequency resolution of ωp/N.

A system comprising:

• a signal generator operable to generate a plurality of discrete tones having a frequency spacing and a frequency offset;
• an IQ modulator coupled to the signal generator, the IQ modulator being operable to provide a modulated signal;
• and
• a frequency analyzer coupled to a channel configured to receive the modulated signal and generate a demodulated signal, the frequency analyzer being operable to perform a Discrete Fourier Transform (DFT) operation on the demodulated signal, the DFT having a frequency resolution equal to the frequency offset.

A method comprising:

• generating a signal comprising a plurality of discrete tones having a frequency spacing and a frequency offset;
• modulating the signal;
• providing the modulated signal to a channel configured to demodulate the modulated signal;
• receiving the demodulated the signal;
• and
• performing a Discrete Fourier Transform (DFT) operation on the demodulated signal, the DFT having a frequency resolution equal to the frequency offset.