This is a book review of 'The Micro-Doppler Effect in Radar' by V. C. Chen. Artech House, 16 Sussex Street, London, SW1V 4RW, UK. 2011. 290pp + diskette. Illustrated. £90. ISBN 978-1-60807-057-2.

'The Micro-Doppler Effect in Radar' by V.C. Chen

IEEE Antennas and Wireless Propagation Letters

Interrupted-sampling repeater jamming (ISRJ) provides a novel coherent-jamming mode against wideband radar. ISRJ allows the single-antenna jammer to periodically sample and repeat a fraction of the intercepted signal, which reduces the sampling rate and achieves transmit-receive isolation. The coherent-jamming signal generated by ISRJ can form multiple verisimilar false targets when received and processed by the victim radar receiver. Moreover, some false targets can precede the real target. This paper surveys the use of ISRJ in linear frequency modulated (LFM) radar jamming. The theory and application of ISRJ has been researched for more than one decade, but what is missing is a completed summary for the framework of this technique. In this paper, mathematic principles of ISRJ against LFM radars, which utilize matched-filter processing, stretch processing, and range-Doppler processing, are developed. The unique jamming effects in radar systems are focused on when the interrupted sampling frequency of the jammer is smaller than the bandwidth of the radar signal. Specifically, the false-target characteristics, including amplitude, space distribution, and phase, are discussed, respectively. On this basis, the key jamming elements, which determine these false-target characteristics, are pointed out and analyzed in detail. At last, simulation and real data are used to verify the correctness of the analyses. Experimental results highlight the potential application of the proposed jamming mode.

Jamming Wideband Radar Using Interrupted-Sampling Repeater

Bistatic inverse synthetic aperture radar (ISAR) operates with spatially separated transmitting and receiving antennas. This study presents a method capable of generating deceptive images from a series of intercepted bistatic ISAR chirp pulses. It is demonstrated that deceptive false-target images will be induced by the under-sampled pulses which are retransmitted to a moving target and scattered by it under the principles of bistatic ISAR configuration. Additionally, the jamming idea is proved to be applicable based on the characteristics of the false-target images and the requirement of jamming power. A scattering model of Yak-42 plane with 330 point scatterers is adopted to verify the effectiveness of the jamming idea.

On deception jamming for countering bistatic ISAR based on sub-Nyquist sampling

This paper addresses the issue of deceptive jamming against synthetic aperture radar (SAR) by using 1-bit sampling and time-varying threshold (TVT). With 1-bit intercepted SAR signal, the multipliers involved in a convolution is replaced by xnor gates, which considerably simplify the jamming signal generation. Moreover, the TVT is used for 1-bit quantization before retransmission to retain the relative amplitude information of the jamming signal. As a result, the proposed deceptive jamming schemes are superior to their conventional counterpart in terms of realization. Effects of harmonics and oversampling are analyzed to evaluate the performance degradations caused by the 1-bit sampling and TVT. Simulation results are provided to confirm the validity of the proposed schemes.

Deceptive SAR Jamming Based on 1-bit Sampling and Time-Varying Thresholds

Shannon-Nyquist theorem indicates that under-sampling at low rates will lead to aliasing in the frequency domain of signal and can be utilized in electronic warfare. However, the question is whether it still works when the compressive sensing (CS) algorithm is applied into reconstruction of target. This paper concerns sub-Nyquist sampled jamming signals and its corresponding influence on inverse synthetic aperture radar (ISAR) imaging via CS. Results show that multiple deceptive false-target images with finer resolution will be induced after the sub-Nyquist sampled jamming signals dealed with CS-based reconstruction algorithm; hence, the sub-Nyquist sampling can be adopted in the generation of decoys against ISAR with CS. Experimental results of the scattering model of the Yak-42 plane and real data are used to verify the correctness of the analyses.

Sub-Nyquist Sampling Jamming Against ISAR With Compressive Sensing

Efficient generation of jamming signal is an important but intractable issue in active deception jamming against synthetic aperture radar. Considerations must be given to both the computational complexity and the focus depth of the false scatterers of a deception template. However, existing methods cannot meet both demands mentioned above when generating jamming signal of an extended false scene or scattered false targets. In this study, a frequency-domain three-stage algorithm (FDTSA) is proposed. In theory, the jammer system is deliberately reformatted in the two-dimensional frequency domain. Accordingly, the implementation of the FDTSA can be effectively accelerated by fast Fourier transform and by separating the modulation process of a repeat jammer into three stages: the offline stage, the initialisation stage and the real-time modulation stage. Theoretical analyses and simulation results indicate that the FDTSA can get rid of severe focus deterioration of the false scatterers and reasonable computational load is required.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-rsn.2013.0222

A frequency-domain three-stage algorithm for active deception jamming against synthetic aperture radar

Deceptive jamming against synthetic aperture radar (SAR) receives intensive interests during the past decade. However, it is still a challenging task to design a jamming method that is competent both in focus capability and in computational efficiency, especially in the case where jammer is confronted with SAR with significant squint angle and long synthetic aperture. In this paper, we propose an inverse omega-K algorithm and present an accurate and an approximate implementation scheme of the algorithm. The accurate scheme can achieve full focus with no regard to the squint angle and synthetic aperture of radar. Its computations include fast Fourier transform (FFT), Stolt interpolation, and complex multiply. Advantage of computational efficiency can be achieved under assumption that the support region of radar can be crudely evaluated a priori so that the most time-consuming Stolt interpolation can be done offline. The support region is determined by carrier frequency and bandwidth of radar signal, pointing direction, and azimuth beam width of radar antenna. For the case in which the support region of radar is not available to jammer beforehand, the approximate scheme is a remedy. By substituting the Stolt interpolation with Chirp-Z transform (CZT), the approximate scheme is readily fit for parallel computation and hence appealing for its high efficiency. However, the focus criterion exerts a limitation on range scale of electromagnetic deception when the squint angle of SAR is large. Both implementation schemes are verified by simulation results.

Xiaoyi Pan

Papers

Jamming Wideband Radar Using Interrupted-Sampling Repeater

On deception jamming for countering bistatic ISAR based on sub-Nyquist sampling

Sub-Nyquist Sampling Jamming Against ISAR With Compressive Sensing

A frequency-domain three-stage algorithm for active deception jamming against synthetic aperture radar

Inverse Omega-K Algorithm for the Electromagnetic Deception of Synthetic Aperture Radar