Photonics-based simultaneous distance and velocity measurement of multiple targets utilizing dual-band symmetrical triangular linear frequency-modulated waveforms

Abstract

The distance and velocity measurement can be obtained by the round-trip time and Doppler effect on the down-chirp and the up-chirp of the linear frequency-modulated waveform (LFMW), but false targets will appear in a multi-target situation, resulting in erroneous detection. Here, we report a photonics-assisted approach to realize unambiguous simultaneous distance and velocity measurement in multi-target situations utilizing a dual-band symmetrical triangular LFMW. Dual-band observation invariance is proposed, to effectively resolve the false targets. The de-chirped signals can be obtained from parallel de-chirping processing to the dual-band echoes. By measuring and calculating the beat frequencies of the de-chirped signals in the two frequency bands, the actual parameter measurements can be acquired according to the authenticity criterion. In the experiments, detections to three targets are performed, and the distance and velocities are acquired without false targets. The absolute measurement errors of the distance and the velocity are less than 9 mm and 0.16 m/s, respectively. These results show the feasibility of the proposed approach.

Multi-Functional Microwave Photonic Radar System for Simultaneous Distance and Velocity Measurement and High-Resolution Microwave Imaging

“…To the best of our knowledge, the proposed distance and radial velocity measurement method using only a single-chirped LFM signal and a single-tone microwave signal has never been reported before in microwave photonic radar systems. Some methods based on photonic approaches have been reported in the last few years to measure the distance and radial velocity of a moving target [22]- [24],…”

“…In [22], the distance of a single stationary target is measured, while the distance and radial velocity measurement of the moving target has not been obtained in the experiment. In [23] and [24], the distance and radial velocity information of a moving target is obtained by utilizing the LFM signals with opposite chirps. However, in their experiments, the echo signal is not reflected by the moving target but is directly generated by the AWG.…”

“…especially the linearly frequency-modulated (LFM) signals [19]- [21]. Based on these technologies, some photonics-based distance and velocity measurement methods have been presented [22]- [24]. Generally, LFM signals with opposite chirps containing up-chirped and down-chirped segments are applied to implement the distance and velocity measurement of a moving target.…”

“…The measured relative errors for distance and velocity are less than 0.005% and 0.59%, respectively. To measure the distance and velocity of multiple targets simultaneously, a photonics-based approach was proposed utilizing dual-band symmetrical triangular LFM waveforms [24]. In their experiment, detection of three targets is performed.…”

“…To meet the increasing demand in military affairs and civilian activities, it is highly urgent to realize the integration of multiple functions into a single radar system [25], [26], such as simultaneously achieving target tracking and imaging. Although the above three methods can achieve distance and velocity measurement [22]- [24], they cannot obtain a clear target shape due to the use of a transmitted signal with opposite chirps. To the best of our knowledge, a multifunctional microwave photonic radar system that can simultaneously achieve distance and velocity measurement and high-resolution ISAR imaging has not yet been described.…”