Advanced Microwave Photonic Waveform Editing: Enabling the Evolution of Radar Systems Into Joint Radar and Spectrum-Sensing Systems

In response to the urgent demand for the development of future radar application platforms from single radar functionality toward integrated multifunctional systems, we show an advanced microwave photonic waveform editing method that enables the editing of arbitrary radar waveforms, equipping them with the capability to perform spectrum sensing. This, in turn, expands single-function radar systems into joint radar and spectrum-sensing systems. We theoretically define and calculate the accumulation function of an arbitrary waveform after passing through a specific dispersive medium and utilize this accumulation function to further design a corresponding binary sequence for editing the waveform. After editing, the accumulation function of the edited waveform approximates that of a linearly frequency-modulated (LFM) signal matching the specific dispersive medium. Thus, the edited waveform can be compressed into a narrow pulse after passing through the dispersive medium, realizing the frequency-to-time mapping (FTTM) for achieving frequency measurement or time–frequency analysis. The concept is verified through both simulation and experiment. Using a dispersion-compensating fiber (DCF) with a total dispersion of −6817 ps/nm, arbitrary waveforms, including a 7-bit Barker phase-coded waveform, an LFM waveform, a nonlinearly frequency-modulated (NLFM) waveform, and a waveform with an “E” time–frequency diagram, are edited and further used for microwave frequency measurement and time–frequency analysis in an ultra-wide bandwidth of 36.8 GHz. The temporal resolution and frequency resolution are 2 ns and 0.86 GHz, respectively.