Fig. 1. DLFM de-chirping principle. (a) Without Doppler shift; (b) add Doppler shift

Fig. 2. Schematic of terahertz signal generation

Fig. 3. Experimental setup (ECL: external cavity laser; AWG: arbitrary waveform generator; EA: electrical amplifier; PM-OC: polarizer coupler; PM-EDFA: polarization-maintaining erbium-doped fiber amplifier; PD: photodiode; HA: THz antenna; ELO: RF source; OSC: oscilloscope; mixer: multiplier; lens: polyethylene lens)

Fig. 4. Constellation point of PS64QAM signal. (a) Constellation point at V=0.06; (b) probability of constellation point at V=0.06

Fig. 5. Output of IQ modulator. (a) Time-frequency diagram of DLFM signal; (b) signal frequency spectrum after IQ modulator

Fig. 6. Terahertz wireless channel transmission characteristics

Fig. 7. DSP signal processing. (a) GSOP, clock recovery; (b) CMMA; (c) FOE; (d) BPS

Fig. 8. BER changed with PD power under different transmission distances. (a) 10 m; (b) 50 m

Fig. 9. SNR of echo signal obtained at different transmission distances

Fig. 10. Echo signal spectrograms. (a) Spectrum diagram of single target de-chirping signal; (b) spectrum diagram of dual-target de-chirping signal

Fig. 11. Echo signal spectrograms adding Doppler shift. (a) Spectrum diagram of single target de-chirping signal; (b) spectrum diagram of dual-target de-chirping signal

Fig. 12. Error graphs under different SNR. (a) Distance error; (b) velocity error

Fig. 13. Perception and communication performance at different time duration ratios