Stepped frequency synthetic preprocessing algorithm for inverse synthetic aperture radar imaging in fast moving target echo model

Abstract

This paper first introduces an accurate inverse synthetic aperture radar echo model for the fast moving targets. In this model, the target's motion during the time periods of the pulse transmitting, propagating and receiving have been taken into account, and some problems, which have been ignored in the 'stop-go' model, may occur, for example, the varied ambiguity numbers and the drifted frequency centre. These problems will cause many difficulties in obtaining a high resolution range profile (HRRP) synthesis. To deal with these problems, a stepped frequency synthetic preprocessing (SFSP) algorithm is presented. The key of the proposed algorithm is synthetic preprocessing, including Doppler ambiguity suppression, echo coherence restoration and frequency centre correction, respectively. By completing the preprocessing, the HRRP can be achieved by a bandwidth synthesis and a well-focused image can be obtained by a keystone transform and an azimuth process, respectively. The simulation results validate the proposed SFSP algorithm by comparing it with the algorithm in the existing extended 'stop-go' model.

Inverse second‐order polynomial time–frequency transform‐based detection of moving targets in the stepped‐frequency radars

“…At first, the aim is to investigate the condition in which the movement is radial with the constant velocity. So, by substituting a R = 0 in (14), the received signal phase is rewritten as…”

“…In this section, it is attempted to investigate the second moving scenario. In this scenario, the moving target has both radial velocity and acceleration which are formulated in (14). Using IS-PTFT to reconstruct HRRP results in having a peak in the right location corresponding to the real place of the target if 2 f 0 v R /cPRF is an integer value.…”

“…This technique is still utilised [11] and its applications are not limited to GPR. Phased array radars with active beam forming [12], synthetic aperture radars (SARs) and inverse SAR [13,14] are some of the applications of this waveform.…”

Wideband distributed coherent aperture radar based on stepped frequency signal: theory and experimental results

“…To improve the system robustness to time synchronisation error, the SF signal, whose characteristic of narrowband of subpulse [26] will reduce the effect of time synchronisation error to coherent performance, is introduced to realise the full coherence technology. The two transmit SF signals of DCAR are, respectively, expressed as and where , u 2 ( t ) = u 1 ( t − Δ τ ) are complex envelopes of two SF signals.…”

Unitary PUMA Algorithm for Estimating the Frequency of a Complex Sinusoid

“…In many applications, such as wireless communications [1], synthetic aperture radar imaging [2]- [3], source localization in radar and sonar systems [4]- [6], and software radio receivers [7], fast and accurate frequency estimation is crucial for proper system operation.…”