Radar clutter suppression and target discrimination using twin inverted pulses

Abstract

The proposition that the use of twin inverted pulses could enhance radar is tested. This twin inverted pulse radar (TWIPR) is applied to five targets. A representative target of interest (a dipole with a diode across its feedpoint) is typical of covert circuitry one might wish to detect (e.g. in devices associated with covert communications, espionage or explosives), and then distinguish from other metal (‘garbage’ or ‘clutter’), here represented by an aluminium plate and a rusty bench clamp. In addition, two models of mobile phones are tested to see whether TWIPR can distinguish whether each is off, on or whether it contains a valid SIM card. Given that a small, inexpensive, lightweight device requiring no batteries can produce a signal that is 50 dB above clutter in this test, the options are discussed for using such technology for animal tagging or to allow the location and identification of buried personnel who opt to carry them (rescue workers, skiers in avalanche areas, miners, etc.). The results offer the possibility that buried catastrophe victims not carrying such tags might still be located by TWIPR scattering from their mobile phones, even when the phones are turned off or the batteries have no charge remaining.

Detection and Location of Nonlinear Scatterers Using Dort Applied With Pulse Inversion

“…DORT (French acronym for decomposition of time-reversal operator) is a technique that utilizes multistatic scattered responses obtained with an array of antennas by means of the eigenvalue decomposition (EVD) to separate the detected targets in terms of the eigenvalues and their eigenvectors, which contain the information necessary to perform selective focusing (beamforming) towards a target of interest [8,9]. PI is a technique that allows either even-or odd-ordered harmonics to be extracted from the linear combination of the scattered responses due to excitation by two transmit pulses, with one an inverted version of the other but otherwise identical [10,11]. Our previous work in [7] has proposed PI-DORT for nonlinear devices by providing examples via a two-dimensional numerical simulation.…”

Radar Spectrum Engineering and Management: Technical and Regulatory Issues

“…Clearly bats leverage a very advanced form of waveform diversity that encompasses a form of simultaneous multimode emission coupled with very sophisticated and highly specialized receive signal processing [43], [44]. A bat can change the nature of this emission according to the particular information being sought (e.g., searching for available prey versus tracking specific prey) while dolphins exploit a form of pulse-to-pulse waveform diversity to distinguish linear scattering from nonlinear scattering [45], [46] (which proves useful in bubble-rich shallow waters). Likewise, bats may leverage echo location as a form of echoic flow for navigation [47], [48] in a manner similar to how other creatures use optic flow to navigate by vision.…”

Nonlinearity and the effect of detection on single-channel synthetic aperture radar imagery

“…The reasoning is that if a signal sampled from a population with an infinite variance is forced to be modeled, or more generally processed, using a linear technique, this process ignores valuable information which can only be exploited through utilizing nonlinear signal processing methods [2]. One of the interesting recent studies on the superiority of nonlinear signal processing for radar is provided in [14]. In that study, a new radar technique that relies on the excitation of nonlinearities in the imaged scene was presented.…”