Nonlinear Radar via Intermodulation of Jointly Optimized FM Noise Waveform Pairs

Owen, Jonathan W.; Mohr, Charles A.; Blunt, Shannon D.; Gallagher, Kyle A.

doi:10.1109/radar.2019.8835590

Cited by 11 publications

(8 citation statements)

References 22 publications

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“…where 𝜂 𝑖 = ℎ d (𝑑 𝑖 ) 𝛽 √ 𝑘 out 𝑅 H 𝑅 rx /𝑅 F . For simplicity, in ( 23)- (25) we ignore the propagation delay in 𝜑(𝑡), on the grounds that 𝜏 𝑖+1 𝑇 s , but we revisit this point later. From (24), the partial sum 𝐴 p,𝑖 𝑒 𝚥 𝜃 p,𝑖 in adjustment slot 𝑖 reflects prior adjustments, so that helper 𝑖 + 1 should change its phase to equal that of the partial sum, 𝜃 p,𝑖 .…”

Section: A Two-mode Transmission With Phase Adjustmentmentioning

confidence: 99%

“…In the absence of error, this maximizes the amplitude of the next partial sum so that 𝐴 p,𝑖+1 = 𝐴 h,𝑖+1 + 𝐴 p,𝑖 . According to (25), the phase offset required to achieve this is…”

Section: A Two-mode Transmission With Phase Adjustmentmentioning

confidence: 99%

“…Consider (25) and note that the individual terms that constitute it are separable with respect to 𝜑(𝑡) via the following integrals…”

Section: B Phase Offset Estimationmentioning

confidence: 99%

“…The general concept of a multi-tone harmonic radar that uses the intermodulation product at the output of a non-linear target has been previously explored in [23]- [25]. However, to the best of our knowledge there has been no prior work on the use of the intermodulation products of multiple helper transmitters to increase the downlink power from a passive, non-linear tag.…”

Section: Introductionmentioning

confidence: 99%

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Harmonic Radar with Adaptively Phase-Coherent Auxiliary Transmitters

Lavrenko,

Cavers,

Woodward

2021

Preprint

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In harmonic radar (HR), the radio frequency transmitter illuminates a nonlinear target (the tag), causing the return signal to consist of harmonics at multiples of the transmitted carrier frequency. Of them, the second harmonic is usually the strongest and the one to which the receiver is tuned. This frequency difference distinguishes the tag reflection from environmental clutter, which remains at the uplink (transmitter to tag) frequency. However, the passive nature of HR tags severely limits the reflected power, and therefore the range of the downlink (tag to receiver) path. We propose to increase the range and/or signal to noise ratio (SNR) by novel restructuring at the physical and signal levels. For this, we accompany the original transmitter with auxiliary transmitters able to send simple tones that are synchronized to arrive at the tag in phase, and we design the receiver to detect an intermodulation component. The resulting range and SNR are much greater than those of the original, conventional HR system, and greater even than if the original system were to transmit with power equal to the aggregate power of our new system. Achieving mutually coherent, i.e., in phase, arrival of the tones at the tag is the focus of the present paper. We provide a system framework that models the tag and the uplink and downlink, then present the adaptive phase coherence algorithm and analyze the probabilistic growth of the output signal power. We also account for the effects of frequency shifts due to transmitter mobility and the frequency offset errors in the transmitter local oscillators.

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Section: A Two-mode Transmission With Phase Adjustmentmentioning

confidence: 99%

Section: A Two-mode Transmission With Phase Adjustmentmentioning

confidence: 99%

“…Consider (25) and note that the individual terms that constitute it are separable with respect to 𝜑(𝑡) via the following integrals…”

Section: B Phase Offset Estimationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Harmonic Radar with Adaptively Phase-Coherent Auxiliary Transmitters

Lavrenko,

Cavers,

Woodward

2021

Preprint

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“…For example, in [43] (with detailed derivation in [44]) gradient-descent optimisation was performed and subsequently demonstrated experimentally to realise waveforms that can reach a lower bound on sidelobe performance for discretised FM waveforms. This general approach was also employed to optimise coded FM waveforms based on Legendre polynomials [45] (and also account for receiver range straddling), to efficiently incorporate spectral notches into FM waveforms [46], to realise an intermodulation-based formulation for non-linear harmonic radar [47], and to design different sub-classes of random FM waveforms [36,37]. Here gradient descent is used to optimise subsets of complementary FM waveforms.…”

Section: Complementary Fm Waveformsmentioning

confidence: 99%

Complementary frequency modulated radar waveforms and optimised receive processing

Jones

Mohr

McCormick

et al. 2021

IET Radar Sonar & Navi

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Design methodologies are developed for complementary frequency modulated (FM) waveforms and for optimised complementary mismatched filtering (MMF) of arbitrary non-repeating waveforms. The former is a sub-class of random FM waveforms denoted as complementary FM (Comp-FM) while the latter extends a practical instantiation of least-squares mismatched filtering yielding the mismatched complementary-on-receive filtering (MiCRFt) scheme. Both of these approaches have an emphasis on the nonideal physical effects of the radar transmitter and receiver, thereby permitting highfidelity simulation analysis and subsequent experimental demonstration of their efficacy using open-air measurements.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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