Dual Mode Radar Research Articles

Moving target detection in range-ambiguous clutter scenario with PA-FDA dual-mode radar

Range-ambiguous clutter suppression is challenging for airborne radar in non-sidelooking geometry. The target detection performance might degrade severely due to range ambiguity and range dependence problems. It is proved that the frequency diverse array (FDA) is capable of resolving the range ambiguity and is beneficial for range ambiguous clutter suppression. However, FDA uses wide coverage transmit beampattern, which causes somewhat gain loss compared to the phased array (PA). In this paper, we establish a PA-FDA dual-mode radar to maximize the advantages of PA and FDA radars to improve target detection performance in range-ambiguous clutter scenario. Firstly, the range ambiguous resolvability of FDA is utilized, where range ambiguous clutters are separated by using pre-filtering before space-time adaptive processing. Therefore, the range dependence compensation algorithms can be performed independently to further address the range dependence problem of non-sidelooking array radar. In this case, the clutter covariance matrix (CCM) is reconstructed by using linear combination of distinguishable CCMs corresponding to different range regions, resulting in improved accuracy of CCM estimation. Secondly, the enhanced CCM is applied in PA counterpart, which maximizes the high beampattern gain of PA and range ambiguity resolvability of FDA. It is verified that the PA-FDA dual-mode radar outperforms the PA or FDA single-mode in simultaneously narrow-beam detection and wide-angle coverage. Thus, the proposed PA-FDA dual-mode radar can greatly contribute to searching and tracking tasks. Simulation examples demonstrate the effectiveness of the proposed method.

Cooperated Moving Target Detection Approach for PA-FDA Dual-Mode Radar in Range-Ambiguous Clutter

This paper proposes a cooperated range ambiguous clutter suppression method for moving target detection in the background of range-ambiguous clutter with a phased array (PA)–frequency diverse array (FDA) dual-mode radar. With the FDA mode, the range-ambiguous clutters are discriminated in the transmit spatial frequency domain, and thus the clutter covariance matrixes (CCMs) corresponding to unambiguous and ambiguous regions can be independently estimated. Therefore, the enhanced CCM can be reconstructed by using a linear combination of these distinguished CCMs from different range regions. With the PA mode, the enhanced CCM is applied, thus taking advantages of its high beampattern gain as well as alleviating the range ambiguous clutter suppression problem. Simulation results are presented to verify the effectiveness of the proposed method in range-ambiguous clutter scenarios.

Iterative multi-target detection for PA-FDA dual-mode radar

In this paper, the multi-target detection for joint phased array (PA) and frequency diverse array (FDA) radars, referred to as PA-FDA dual-mode radar, is investigated by exploiting the high transmit power efficiency of PA as well as wide spatial coverage of FDA. The PA-FDA dual-mode radar is formulated in a signal-level fusion manner by combining the PA and the FDA, which enables us to exploit the joint information in the PA-FDA dual-mode radar. In the sequel, an iterative multi-target detection method is devised with two main steps: i) the generalized likelihood ratio test (GLRT) is performed, which provides the knowledge of target parameters, and ii) the conditional-cancelation-before-detection GLRT (CCBD-GLRT) detector is carried out, which detects other targets based on the previous detection knowledge. At the analysis stage, the optimal detector is provided for the signal-level fusion of PA and FDA radars. Moreover, the corresponding analytical expressions of the probabilities of detection as well as the probabilities of false alarm with respect to both the developed GLRT and CCBD-GLRT detectors are derived for multi-target detection. Simulation results demonstrate that the proposed multi-target detection method is effective and the PA-FDA dual-mode radar outperforms the PA and the FDA radars.

Dual-Mode Radar Sensor for Indoor Environment Mapping.

In this paper, we introduce mapping results in an indoor environment based on our own developed dual-mode radar sensor. Our radar system uses a frequency-modulated continuous wave (FMCW) with a center frequency of 62 GHz and a multiple-input multiple-output antenna system. In addition, the FMCW radar sensor we designed is capable of dual-mode detection, which alternately transmits two waveforms using different bandwidths within one frame. The first waveform is for long-range detection, and the second waveform is for short-range detection. This radar system is mounted on a small robot that moves in indoor environments such as rooms or hallways, and the radar and the robot send and receive necessary information to each other. The radar estimates the distance, velocity, and angle information of targets around the radar-equipped robot. Then, the radar receives information about the robot’s motion from the robot, such as its speed and rotation angle. Finally, by combining the motion information and the detection results, the radar-equipped robot maps the indoor environment while finding its own position. Compared to the actual map data, the radar-based mapping is effectively achieved through the radar system we developed.

K-Band Single-Path Dual-Mode CMOS Transmitter for FMCW/UWB Radar

A K-band dual-mode radar transmitter is implemented with 0.13- $\mu \text {m}$ CMOS technology, which supports both FMCW and UWB radar operations. A dual-functional block is proposed to achieve efficient dual-mode operation without additional paths and switches. It is switched between a pulse former and a differential amplifier for UWB and FMCW modes, respectively. As a result, the transmit signal can become either a linearly frequency-modulated signal or a time-slotted pulse signal according to the selected mode. It showed performance comparable to that of previously reported transmitters despite the fact that it operates in dual modes.

VELOCITY ERROR ANALYSIS OF A K-BAND DUAL MODE TRAFFIC RADAR

This paper is addressed to a design of K-band dual mode radar used in traffic information collection. The radar can work in both Frequency Modulate Continual Wave (FMCW) mode and Continual Wave (CW) mode. As VCO is seldom used as the oscillator in CW radar for velocity measurement, this paper studied the effect of phase noise and detecting distance on velocity error in CW mode in VCO design. The analysis shows that the effect of phase noise on velocity error can be reduced by shortening the detecting distance. There’s little difference in short-range velocity measurement between the dual mode radar with MMIC VCO and the CW radar with low phase noise oscillator.

AVTIS: A novel millimetre-wave ground based instrument for volcano remote sensing

During May and June 2004, we tested a novel, millimetre-wave ground based, dual-mode radar and radiometer on Soufrière Hills Volcano, Montserrat. AVTIS (All-weather Volcano Topography Imaging Sensor) has an active (radar) mode designed to image the distance to lava domes on volcanoes whose summits are commonly obscured by persistent cloud, such as Soufrière Hills Volcano. The passive (radiometer) mode can be employed to measure the surface temperature of the imaged topography. In its current form, AVTIS can be deployed by two people and takes 50 min to acquire a 20° × 5° scene at 0.1° increments. During the fieldwork period the lava dome was not growing and only the radar mode was used. The data recorded indicate that the maximum distance imaged was about 3800 m. Combining datasets acquired from different viewpoints can potentially provide a full 3D topographic model. The accuracy and completeness of this reconstruction are reduced by two factors. Firstly, relatively small grazing angles of the ground-based line-of-sight rendered incised valleys invisible. Secondly, methods currently used to orient the instrument limit the accuracy of the resulting topographic information. Nevertheless, valuable information on new topographic surfaces was obtained in an area north of the lava dome where a valley has been infilled by deposits and in the amphitheatre created by the giant collapse event of July 2003.

An X-Band Front-End Module Using HTS Technique for a Commercial Dual Mode Radar

A front end module of receiver has been designed to eliminate the interference between the tracking and searching radar used in commercial radar application. The module is located at the receiving path of the searching radar. The proposed module includes two parts, the HTS superconducting filter and cryogenic low noise amplifier. The bandwidth of the eight-resonator HTS hairpin filter is 2% at the X-band frequency. Low insertion loss (below1 dB) and good skirt rejection (down to 60 dB at 50 MHz from the pass-band edge) are obtained. The two-stage low noise amplifier is designed by commercial low noise HEMT devices, NE321000. Two Lange couplers are located at output and input port of each amplifier stage to improve the return loss and to make LNA easily match to optimal low noise impedence. The cryogenic amplifier shows 30 dB gain and 0.4 dB NF at 77 K in X-band. A very high rejection is necessary for the elimination of unwanted spurious signals. The acceptable specification is 110 dB down at 500 MHz away from the band-edge of the filter. In general, the skirt rejection of a hairpin HTS filter is pretty good near the pass-band edge, but may become worse far from the pass-band edge. To meet the requirement of this commercial radar application, a high rejection suspended stripline filter is put after the low noise amplifier. The whole module shows an maximal NF of 1.5 dB, a gain of 25 dB around pass-band frequencies, and a rejection of better than 110 dB at 500 MHz away from the band edge of the filter. It totally solves the interference problem in this dual mode radar.

Des systèmes radar dédiés à l'anticollision

This paper describes research which has been conducted at inrets and the Institut d'electronnique et de micro-électronique du Nord into road traffic applications of microwave detectors, which are known as collision warning systems. The main purpose of such systems is to improve driver safety by giving a danger warning. The paper begins with a description of the principles of the system and describes the various mock-ups which have been built inrets. These consisted initially pulsed radars at 10 and 60 GHz and then a 60 GHz linear frequency modulated continuous wave radar. Subsequently, frequency modulated and pulsed radars, which complement each other well, were combined in what we have termed a dual mode radar, which although it covers all the required distances is nevertheless costly. This led us to undertake a theoretical study of a last type of radar based on binary coding using pseudorandom sequences and a correlation receiver. Finally, a 10 GHz prototype based on a Digital Signal Processor ( dsp) has been able to solve the cost problem. It is accurate to within about two metres over all required distances. The system is able to discriminate between several obstacles and recognize them on the basis of their radar cross section.