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Radar, navigation and tracking systems
Published in Geoff Lewis, Communications Technology Handbook, 2013
Azimuth information about the arrival of an electromagnetic wave at a receiving antenna can be obtained by both amplitude and phase measurements. Direction finding therefore involves either evaluating the voltage developed on a very directional rotatable antenna or by taking time/phase difference measurements. Although both methods have much in common, most modern systems adopt the latter technique. Operation in the VHF or UHF bands is often adopted to ensure that DF systems can operate with small but highly directional antennas.
A New Generation of Intrusion Detection Networks
Published in Fei Hu, Qi Hao, Intelligent Sensor Networks, 2012
Jerry Krill, Michael O’Driscoll
From a distance, a directional receiver tuned to the frequency band(s) or tone(s) of the pebble nodes scans the sensor field to monitor activity. The directional antenna may, for example, determine pebble signal activity above normal at a particular direction. The strength of the received signal would be proportional to the strength of pebble detection activity, implying a firm indication of detecting an intruder. The angle of reception, for example, from a direction-finding antenna, indicates the approximate location of the intruder. Multiple remote directional receivers could be operated for triangulation to further localize the swarm activity. A similar localization approach would be to have pebbles at different locations radiating at different tonal frequencies. The remote receiver would be able to link the sensor net activity to a command and control (C2) node for action, if indicated. For example, a swarm activity indicating a high confidence of detection could result in a decision to intercept the detected intruder. The remote receiver could be manned and the C2 decision made at that location, or it could be unmanned and operated remotely via a communications link to a security office. Additional options with this type of operation include cueing of video cameras and tripping an audible or silent alarm if activity of the nodes exceeds a threshold, enabling a response by security forces.
A Cauchy score DOA estimator for monostatic MIMO radar in impulsive noise environment
Published in International Journal of Electronics, 2021
Letao Xu, Shuman Wang, Xiaoyi Pan
Direction of arrival (DOA) estimation plays an important role in radar, sonar and mobile communications (H. Chen et al., 2016; W. Zhang et al., 2018). One kind of unprecedented array configuration with transmitting orthogonal waveform, known as multiple input multiple output (MIMO) radar, has attracted significant attention due to its ability to extend the array aperture by virtual sensors, leading to higher spatial resolution, better parameter identifiability, greater flexibility in the beampattern design and more degrees of freedom (DOFs) compared with conventional phased-array radars. The configurations of MIMO radar can be divided into two categories, one is named as statistical MIMO radar (Haimovich et al., 2008) and the other is collocated MIMO radar (Li & Stoica, 2007). Furthermore, collocated MIMO radar includes bistatic and monostatic MIMO radar. For bistatic MIMO radar, the direction of departure (DOD) and DOA need to be estimated due to the separated transmit and receive arrays. While for the monostatic MIMO radar, DOD and DOA are the same due to its closely located arrays. In this paper, the direction finding problem of monostatic MIMO radar in impulsive noise environment is investigated.
A year-long assessment of wave measurements retrieved from an HF radar network in the Gulf of Naples (Tyrrhenian Sea, Western Mediterranean Sea)
Published in Journal of Operational Oceanography, 2019
Simona Saviano, Alkiviadis Kalampokis, Enrico Zambianchi, Marco Uttieri
The performance of the HF radar system operating in the GoN supports the idea that HF radars can qualify for wave field operational applications (Wyatt et al. 1999), though still needing standardised QA/QC procedures for both post-processing and real-time uses (Wyatt et al. 2011). In addition, direction-finding systems like SeaSonde require the validation of the assumption of spatial homogeneity along each annulus, while phased array ones do not (Graber et al. 1997; Wyatt et al. 2006). The accuracy of wave measurement must also be considered in relation to the inversion method adopted and to the operating frequency of the system. The major shortcoming of radar technology is the lack of continuity in measurements, due to inherent limitations in the physics of the phenomenon (Wyatt et al. 1999). Improvement in background theory and signal filtering (Wyatt et al. 2011), as well as the implementation of more refined algorithms for the retrieval of wave parameters (Lopez et al. 2016), are necessary actions to be taken in light of operational uses.
Simulation and Synchronous Generation of Radar Signals at Geographically Distributed Sensors for Testing Emitter Location Systems
Published in IETE Journal of Research, 2023
Sudha Rani Suram, Niranjan Prasad, Sasibhushana Rao Gottapu
Emitter Location Systems (ELS) track on-board RF signal transmissions and thereby Airborne Emitters using multiple passive Electronic Support Measures (ESM) Systems distributed geographically over a few tens of kilometres. Emitters of interest include on-board Radars, Secondary Surveillance Radars like ADS-B, Mode-S, IFF, DME, etc. The ELS implementation methods include Triangulation from Multiple (minimum two) Direction Finding ESM Systems [1], Emitter Location by a Direction Finding System on the move [2]. Received Signal Strength based Emitter Location [3], Time of Arrival based Hyperbolic Multilateration, [4], Scanning Emitter Localization using a scan rate of the Emitter [5], Hybrid approaches [6,7], etc.