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Cognitive radar is a new paradigm to conceive the next radar generation characterized by unique and amazing features inspired to mental abilities and processes related to knowledge. It goes beyond the usual extraction of information from the measurements and requires the radar to get intelligence. Introduced by Haykin [1] and Guerci [2], it is attracting huge attention within the radar community during...
In this paper, a double V-chirp waveform scheme is employed to suppress the false targets present in the delay-Doppler maps, which are caused by the use of traditional V-chirp transmitted signal in multiple targets environment. Then a family of nonlinear processing methods are applied and the delay-Doppler resolutions of these two waveform schemes are also compared, proving that the proposed waveform...
Global Navigation Satellite Systems - Reflectometry (GNSSR) is an innovative and promising tool for remote sensing purposes. Several applications have been developed to extract geophysical information of the reflected scene from the measured delay waveforms and Delay-Doppler Maps (DDMs). Recently, techniques have been presented to deconvolve the DDMs to reconstruct the Normalize Radar Cross Section...
This paper concerns the on-board data volume reduction for a single-platform multichannel Synthetic Aperture Radar (SAR) system. In such a system, the unambiguous Doppler spectrum reconstructed on-ground is enlarged at the cost of an increased amount of acquired data. Since the signals received by a multichannel SAR instrument are intrinsically correlated, such correlation can be exploited to represent...
This paper describes methods for velocity determination in high dynamic flight using a stand-alone single-frequency GPS receiver. The work is of interest, and the proposed scheme is valuable for practice. Simulations are developed with a GPS signal simulator and a GPS receiver,where the aircraft velocity is up to 7000 m/s, and the acceleration is up to 7 g (9.8m/s2). The performance of the receiver...
Previous channel measurement campaigns in millimetre wave bands were mostly focussing on time invariant channels of static environments. Highly directive antennas were swept in azimuth and elevation angle to extract the angular profile of the double-directional radio channel. This angular profile is also visual in the Doppler domain. Therefore, contrary to common Doppler modelling, close scattering...
Accomplish of reliability and high data rate over the time-varying multipath acoustic channel is very challenging. In this paper, we propose Multiple-Input and Multiple-Output (MIMO) system using Hyperbolic Frequency Modulation (HFM) waveform. Our system combines the advantages of both system, the spatial multiplexing of MIMO and Doppler-tolerance of HFM. To increase spectral efficiency, we use M-ray...
The acquisition of reflected GPS signals on the ocean requires a high sensitivity receiver, high receiving antenna gain and averaging over a long period of time because of their low power. Typically, the receiver integrates 1 ms of signal coherently and averages 1000 of these results non-coherently, using a total signal time of 1 second to generate 1 delay-Doppler map, which is used to retrieve information...
This paper presents a new time-effective GPS acquisition algorithm that improves the Time to First Fix (TTFF) of hardware GPS receivers under power consumption or hardware constraints. Based on a modified Serial Search Acquisition Algorithm (SA), this enhanced alternative, called Reduced Two Steps Acquisition (RTSA), provides an average gain of 64.18% in number of SA calculations. In terms of speed-up...
In this paper, two-thread based signal tracking and acquisition process was designed. In general, the signal acquisition process is performed slower than the tracking process. For the reasons menthoned above, the results of acquisition from a few seconds later can be provide to tracking loop. To solve the problem, we proposed a correction method that the past of code phase can be corrected as currently...
Civilian GNSS signals are highly vulnerable to structural interference due to publicly known signal structure and lack of encryption. This type of interference includes counterfeit GNSS like signals that are designed to deceive target GNSS receivers without being detected. A synchronized structural interference signal can mislead the tracking process of a receiver which may lead to the generation...
In a recent paper, we have proposed a filter bank multicarrier spread spectrum (FB-MC-SS) waveform as a new method for wideband spread spectrum communications in HF bands. We have noted that FB-MC-SS is well suited for this application because of its robustness against narrow and partial band interference and because it has good performance over a wide range of delay and Doppler spreads. In this paper,...
In this paper three-dimensional channel estimation for passive radar using Orthogonal Frequency Division Multi-plexing(OFDM) waveforms is proposed. The passive radar has gained plenty of interests for the covert operations while the detection of the target signal is one of its issues. In modern communication systems, Single Frequency Network (SFN) has been used. This leads to the difficulty to determine...
This research focuses on improving GNSS carrier phase tracking performance in multipath fading environments. A new approach based on frequency diversity combining at correlator level is proposed to enhance carrier phase estimation robustness. The proposed method works on the fact that in a multipath environment the fading observed in different frequency bands is independent of each other. The uncorrelated...
Previously unreported phenomena of distributed target multipath observed with passive radar systems are presented and discussed. Trail-like signatures in the range-Doppler surface are shown from UHF Digital Television passive experimental trials with commercial airliner targets. Simulated results for distributed ground multi-bounce paths demonstrate a high degree of similarity to the empirical observations,...
Geo-locating moving targets using sequential imaging while exploiting their spatio-temporal proximity is addressed in this paper for bistatic Linear Frequency Modulation (LFM) and Orthogonal Frequency-Division Multiplexing (OFDM) scenes. The approach consists of three major steps (i) Synthetic Aperture Radar/Along-Track Interferometry (SAR/ATI) imaging for moving target detection; (ii) target velocity...
Cognitive radar (CR) has recently been considered as a natural next step for traditional radar. The cognitive property assumes both transmitter and receiver to be able to dynamically adapt to environment changes. In this work, we propose to exploit sub-Nyquist sampling methods that have been originally proposed to reduce the sampling rate bottleneck at the receiver. For CR, we extend this approach...
The widespread availability of consumer grade drones in the recent time has lead to new security and surveillance challenges. The detection and localization of these unmanned aerial vehicles (UAV) mark an essential step to identify possible risks at an early stage before taking appropriate countermeasures. This paper describes the results of an experimental trial conducted to examine the detectability...
There are high range sidelobes for Pseudo-random Code Phase Modulation Continuous Wave (PRC-CW) radar due to the characteristics of the code waveform. In order to suppress the range sidelobes and improve the detection performance, we present a method on the basis of Gold sequence. Given a bunch of Gold coded waveforms, a randomly selected waveform is transmitted. The receiver has the knowledge of...
This paper focuses on the signal modeling and character analysis in the passive radar system using global navigation satellite system (GNSS) satellites as illuminators of opportunity. The signal model derived from the GNSS tracking loop shows that it contains information of both the scatter coefficient and the signal Doppler. An experiment using metal board as target was carried out and the results...
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