Linear step frequency waveforms can achieve large time-bandwidth product by uniformly inter-pulse stepping, but have limited anti-jamming ability. Hopped-frequency overcome the limitation introducing irregularly or randomly stepped frequency. However, a challenge in hopped-frequency waveform design is that, given fixed pulse number and product, distribution of its autocorrelation sidelobe varies significantly under different combinations. In this study, authors propose an adaptive gradient...

Abstract Interrupted sampling repeater jamming (ISRJ) with flexible modulation parameters and coherent processing gain seriously threatens the radar detection system. The suppression target performance of existing anti‐jamming methods are limited by strong noise signals. An ISRJ method combining multiple extended complex‐valued convolutional auto‐encoders (CVCAEs) compressed sensing (CS) reconstruction is proposed. For different tasks parameter estimation signal denoising, CVCAEs including a...

A constant false alarm rate (CFAR) target detector in non-homogenous backgrounds is proposed. Based on K-sample Anderson-Darling (AD) tests, the method re-arranges reference cells by merging homogenous sub-blocks surrounding cell under test (CUT) into a new window to estimate background statistics. Double partition test, clutter edge refinement and outlier elimination are used as an anti-clutter processor proposed Modified AD (MAD) detector. Simulation results show that MAD based outperforms...

Conventional stepped‐frequency (SF) waveform utilises the frequency step between pulses to span a wide bandwidth. However, size is limited by width of pulse prevent grating lobes, and first lobe about −13 dB due uniformly sampling in frequency. Modulating [e.g. phase‐coded (PC) modulation or linear modulation] can increase improve performance sidelobes, but sidelobes modulated SF are still not best. In this study, PC frequency‐hopping (PCFH) achieve optimal extend‐range correlation...

By properly transmitting pulses through the clear frequency bands, hopped-frequency (HopF) waveform can achieve a large synthetic bandwidth while avoiding complexity of wideband hardware as well mutual interference to/ from adjacent RF users.To optimally design HopF with low range sidelobes under given spectral constraints, we propose two-step-based approach in this paper.In first step, deterministic is presented to produce rough approximation optimum solution address non-convexity design.In...

This study considers the unimodular sequence train design with low central and recurrent autocorrelation sidelobes. The authors attain goal by minimising integrated energy in autocorrelations user‐supplied weights. They devise a way to employ fast Fourier transform calculating both objective function its gradient, such that considered problem can be efficiently solved using general gradient method. Numeric results indicate proposed method effectively suppress range sidelobes concerned it of...

Performance bounds on range resolution and sidelobe level are built for waveforms with spectral notches. In this study, the authors use integrated mainlobe energy (IME) (ISE) of autocorrelation function to assess performance level, respectively. By considering minimisation weighted sum IME ISE under given constraints, they derive optimal power spectrum density condition subsequently calculate best achievable ISE. With radar system can (i) analyse trade-off relationship between thus better...

The design of unimodular sequence train with low central and recurrent autocorrelation sidelobes is considered. problem formulated as a minimisation the integrated energy in autocorrelations user‐supplied weights an iterative method proposed for it. computationally efficient, its main computation can be implemented using FFT. Numeric results are reported to validate method.

The performance of high‐frequency hybrid sky‐surface wave radar (HFSSWR) is known to suffer from the spread Doppler clutter (SDC). As a major source SDC, ionospheric generally possesses high directivity within main detection range. Classical coherent sidelobe cancellation method provides an efficient way suppress highly directional clutter. However, it performs poorly when directions target and are both in lobe. To address this problem, novel suppression using oblique projection proposed,...

Conventional stepped-frequency (SF) waveform achieves wideband via inter-pulse frequency diversity, however its step is limited below the reciprocal of pulse duration to avoid grating lobes. Applying modulated pulse, e.g. phase coded modulation (PCM) or linear (LFM), overcome above limitation and makes it possible obtain a wider band with same number pulses. But SF still not optimal in sense range correlation sidelobes for two reasons. First, as equally spaced, autocorrelation inside...

Coherent train of pulses can obtain high Doppler resolution, but leads to range and ambiguity. Thus, the staggered pulse repetition frequencies are presented extend unambiguous or coverage. However, there various disadvantages either in pulse-to-pulse stagger block-to-block stagger. In this study, inspired by compensation processing, a modified (RD) processing method is proposed. Correspondingly, waveform design scheme matching also presented. The RD associated with designed effectively...

Coherent pulse train can obtain high Doppler resolution, but leads to range and ambiguity. Thus, the staggered repetition frequencies (PRFs) is proposed extend unambiguous or coverage. However, there are various disadvantages in pulse-to-pulse stagger block-to-block stagger. In this paper, inspired by compensation processing, we propose a modified range-Doppler (RD) processing method. Moreover, waveform design scheme matching method also presented. The RD associated with designed effectively...

For conventional pulse-Doppler radars, the frequency of radar must remain constant over whole coherent integration time. high-frequency surface-wave radar, time can be as long several minutes. This means that permitted to transmit in a particular channel for presents problem when there is requirement switch another whenever are other users band. In this paper, robust and effective algorithm adopted maintain gain while operating frequency-agility mode. (6 pages)

It has been shown in traditional single antenna radar that designing transmit waveform with an ambiguity function exhibits low values specific range-Doppler bins can enhance target detection performance the clutter from these bins. This letter extends this idea to case of multiple-input multiple-output (MIMO) radars and deals design a unimodular set desired MIMO function. The phase-coded sequences are generated by minimizing unified metric represent weighted integrated sidelobe level (WISL)...

Abstract The existence of ionosphere clutter, the target limits performance high frequency surface wave radar (HFSWR). It is more desirable to solve problem clutter mitigation. Existing methods suffer difficulty when nonstationary. To overcome this issue, a novel ionospheric mitigation algorithm based on Time‐Frequency‐Ridgelet Filtering (TFRF) proposed in paper. Our study shows that time‐frequency ridgelet coefficients are nonstationary, whereas targets' stationary. Therefore, can be...

In this paper, we consider the synthesis of planar array with arbitrary aperture shape. The objective is to optimally fix elements' locations reduce peak sidelobe level (PSL) factor (AF) under interelement spacing constraints. problem formulated as a minimax optimization and it then solved by our previously proposed adaptive gradient search (AGS). Key issues are discussed achieve constraints shape control. As degrees freedom (DoFs) elements fully exploited, global searching enabled involving...

We deal with the unimodular waveform design for cognitive radar in signal-dependent interference (clutter). In addition to signal-to-clutter-plus-noise ratio (SCNR), we also consider filtered integrated sidelobe level (ISL) and optimize these two metrics simultaneously. It is assumed that can obtain environment information based on database prior return. relate SCNR ISL signal power spectrum density (PSD) compare optimal PSDs optimizing solely. found are coupled a conflicting way. So,...

In this paper, we suggest the hopper-frequency (HopF) waveform for cognitive probing in spectral congested environment. Similar with stepped-frequency (SF) waveform, HopF is very easy implementation and processing. Besides, it also has necessary degree of freedom (DOF) to achieve high spectrum efficiency suppress range sidelobes, thanks its flexible carriers. echo analyzed associated signal-to-noise ratio (SNR) gain correlation output under different filtering schemes are deduced assumption...