Fig. 1. Multifrequency measurement system. (a) System principle; (b) spectra of the corresponding positions in Fig. (a)

Fig. 2. Channel power ratio at different c values. (a)c=0.3; (b)c=0.5; (c)c=0.7; (d)c=0.9

Fig. 3. Optical frequency comb at c=0.9

Fig. 4. Beat frequency of single-frequency signals. (a) 6.7 GHz; (b) 12.4 GHz; (c) 28.2 GHz; (d) 33.5 GHz

Fig. 5. Beat frequency of multi-frequency signal. (a) 2.4 GHz ,7.8 GHz; (b) 13.1 GHz,35.5 GHz; (c) 2.4 GHz,13.6 GHz, and 25.4 GHz; (d) 6.4 GHz,14.7 GHz,28.2 GHz, and 30.5 GHz

Fig. 6. Frequency measurement results. (a) Variation curve of measurement results with input RF; (b) measurement error curves

Fig. 7. IMFM system with free ambiguity.

Fig. 8. Comparison of frequency spectra before and after frequency ambiguity

Fig. 9. Beat frequency power ratio of RF signal at different powers. (a) -14 dBm; (b) -12 dBm; (c) -10 dBm; (d) -8 dBm

Fig. 10. Power curves and errors under different input signal powers. (a) Estimated power and corresponding power ratio; (b) frequency estimated error

Fig. 11. Beat frequency results of multi-frequency signals at different powers

Fig. 12. Power curves and errors of MZM under different biases. (a) Estimated power and corresponding power ratios; (b) frequency estimated error

Fig. 13. Beat frequency results of multi-frequency signals at different power levels with MZM bias drift of ± 0.2%