Photonic joint radar and communication system using a chirp-polarity coded LFM waveform

A photonic joint radar and communication system using a frequency improved, bandwidth doubled, chirp-polarity coded linear frequency modulation (LFM) waveform is proposed and demonstrated. In the scheme, a dual-polarization modulator is driven by a repetitive LFM waveform and an RF signal to generate different optical sidebands in two orthogonal polarization directions. Then, the orthogonally polarized optical sidebands are filtered and polarization modulated to achieve chirp-polarity coding. The generated signal is employed to simultaneously perform dual functions. Both the radar echo and the communication reception are processed based on optical de-chirping. The approach is demonstrated by simulation. A chirp-polarity coded LFM waveform with central frequency of 24 GHz, bandwidth of 8 GHz, bit rate of 10 Mbit/s is generated and processed for dual functions. The radar range resolution, unambiguous range, and range-Doppler resolution are investigated. The optical demodulation of the communication is verified, and the speed improvement of communication is discussed.