Fig. 1. Time-domain signal and corresponding spectra of (a) scattering clutters in the echo and (b) target-reflected signal light when attenuation length is 9

Fig. 2. SCR versus modulation frequency under AL=11 and AL=12

Fig. 3. Experimental setup with plate (a) or plate (b)

Fig. 4. Time-domain signal and corresponding spectra of (a) scattering clutters in the echo and (b) target-reflected signal light when AL=10

Fig. 5. In the spectrum of the (a) scattering clutters in the echo and (b) target-reflected signal light, amplitude of modulation frequency versus the modulation frequency at different ALs

Fig. 6. SCR versus modulation frequency under AL=11 and 12

Fig. 7. Ranging experimental setup

Fig. 8. Ranging results for different modulation frequencies in clean water

Fig. 9. Ranging results for different modulation frequencies in different ALs