Detection of objects by synthetic aperture FM‐CW radar
01 Jan 1992-Electronics and Communications in Japan Part I-communications (Wiley Subscription Services, Inc., A Wiley Company)-Vol. 75, Iss: 3, pp 85-94
TL;DR: In this paper, the principle of the synthetic aperture technique for the conventional FM-CW radar was considered and the fundamental detection results of objects placed in the free space were presented. But the results were limited to an anechoic chamber using an explored radar system.
Abstract: The frequency-modulated continuous-wave (FM-CW) radar is suitable for detecting objects placed in the near range compared to the pulse radars. This paper considers the principle of the synthetic aperture technique for the conventional FM-CW radar and presents the fundamental detection results of objects placed in the free space. A laboratory measurement is carried out to detect a metallic plate and a pipe in an anechoic chamber using an explored radar system operative in the microwave X-band. This demonstrates the high resolution detection in azimuth direction in the Fresnel region. It is shown that the radar has a potential ability in imaging objects placed in the near range.
Citations
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TL;DR: In this paper, a multi-beam and multi-range (MBMR) radar with frequency modulated continuous wave (FMCW) waveform and digital beam forming (DBF) algorithm is proposed to cover a detection area of long range and narrow angle (150m, §10 - ) as well as short range and wide angle (60m, 30 - ), as a single 24GHz sensor.
Abstract: In this paper, we propose a multi-beam and multi-range (MBMR) radar with frequency modulated continuous wave (FMCW) waveform and digital beam forming (DBF) algorithm to cover a detection area of long range and narrow angle (150m, §10 - ) as well as short range and wide angle (60m, §30 - ) as a single 24GHz sensor. The developed radar is highly integrated with multiple phased-array antennas, a two-channel transmitter and a four-channel receiver using K-band GaAs RF ICs, and back-end processing board with subspace- based DBF algorithm. The proposed 24GHz MBMR radar can be used for an adaptive cruise control (ACC) stop-and-go system which typically consists of three radars, such as two 24GHz short-range radars for object detection in an adjacent lane and one 77GHz long- range radar for object detection in the center lane.
33 citations
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TL;DR: The synthetic aperture technique is explained with emphasis placed on showing that the Fourier transformed beat signal obtained by the FM-CW radar is equivalent to one kind of Fresnel hologram, which leads the authors to use the SAR technique.
Abstract: Presents the principle of synthetic aperture frequency modulated continuous wave (FM-CW) radar and demonstrates the detection results of several objects buried in natural snowpack using the radar system. First, the synthetic aperture technique is explained with emphasis placed on showing that the Fourier transformed beat signal obtained by the FM-CW radar is equivalent to one kind of Fresnel hologram, which leads the authors to use the SAR technique. Then a radar system operative in the microwave L-band is explored to detect objects buried in natural snowpack. Several detection results are presented demonstrating the potential capability of high resolution imaging in the azimuth direction, comparing with real aperture images. >
25 citations
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TL;DR: It is shown possible to extract the target range and angular position by analyzing the target echo in both time and frequency domains by adding a frequency scanning antenna to a conventional frequency modulated continuous wave radar.
Abstract: This paper proposes the addition of a frequency scanning antenna to a conventional frequency modulated continuous wave radar with possible application to an anti-collision system in a vehicle. It is shown possible to extract the target range and angular position by analyzing the target echo in both time and frequency domains. The proposed system is simple to implement, without requiring the sophisticated wide-band amplifiers and timing circuitry required in a conventional pulse radar. Initial measurements show the feasibility of the proposed system.
23 citations
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TL;DR: In this paper, a phase sensitive radio-echo sounder (pRES) is used to measure the orientation of dip internal reflectors and the potential deviation from nadir of their associated reflections, extending the capabilities of pRES beyond conventional depth sounding.
Abstract: The phase-sensitive radio-echo sounder (pRES) is a powerful new instrument that can measure the depth of internal layers and the glacier bed to millimetre accuracy. We use a stationary 16-antenna pRES array on Store Glacier in West Greenland to measure the three-dimensional orientation of dipping internal reflectors, extending the capabilities of pRES beyond conventional depth sounding. This novel technique portrays the effectiveness of pRES in deriving the orientation of dipping internal layers that may complement profiles obtained through other geophysical surveying methods. Deriving ice vertical strain rates from changes in layer depth as measured by a sequence of pRES observations assumes that the internal reflections come from vertically beneath the antenna. By revealing the orientation of internal reflectors and the potential deviation from nadir of their associated reflections, the use of an antenna array can correct this assumption. While the array configuration was able to resolve the geometry of englacial layers, the same configuration could not be used to accurately image the glacier bed. Here, we use simulations of the performance of different array geometries to identify configurations that can be tailored to study different types of basal geometry for future deployments.
19 citations
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13 Sep 1994
TL;DR: The first experiments conducted by GESMA are encouraging as mentioned in this paper, and the infrastructure of measurements, set up for the acquisition of data from a sonar with a synthetic aperture array, the motion of which is perfectly known, is described.
Abstract: The application of synthetic aperture for sonars is hindered by the major difference between the celerity of acoustic waves for sonars and the celerity of electromagnetic waves for radars. This difference entails a greater sensitivity of signal processing to phase instabilities due to the inhomogeous medium or due to the unsteadiness of the sonar carrier. Nevertheless, the constant progress achieved in computing power, in the precision of inertial stations and in signal processing, should lead to sonars with synthetic aperture arrays in a near future. In that respect the first experiments conducted by GESMA are encouraging. The characteristics of the synthetic aperture are described, as well as the problems related to its application to the sonar field. The infrastructure of measurements, set up for the acquisition of data from a sonar with a synthetic aperture array, the motion of which is perfectly known, is described. The experimental results and a number of images obtained with real targets from the measurements are shown. >
9 citations
References
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TL;DR: In this article, a 3D imaging reconstruction technique using multifrequency holography is proposed that is applied to recognize the shapes of the objects buried in snow using an experimental system using X-band microwaves.
Abstract: The three-dimensional (3-D) imaging of objects buried in snow using multifrequency holography is discussed. It is pointed out that the cross-sectional images obtained by radar used for target detection in soils, sand, and snow do not meet expectations in identifying the shapes of targets. A 3-D imaging reconstruction technique using multifrequency holography is proposed that is applied to recognize the shapes of the objects buried in snow. An experimental system using X-band microwaves was constructed and image reconstruction was accomplished mathematically by computer, with the image displayed on a CRT using a specially designed circuit. Field trials are reported in which it was possible to obtain 3-D images of metallic cylinders and a mannequin buried in snow. >
20 citations
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TL;DR: In this article, a subsurface radar system for imaging buried pipes was developed, which is capable of reconstructing clear pipe images under unfavorable conditions, such as large attenuation rate of the radio waves propagating in soil.
Abstract: A subsurface radar system for imaging buried pipes was developed. The system is capable of reconstructing clear pipe images under unfavorable conditions, such as large attenuation rate of the radio waves propagating in soil. The output power of a pulse generator, the amplifier gain, and average number are controlled by moving the observation depth to improve the detection capability. Fast image processing methods are also used. A 6.5-cm-diameter steel pipe, buried at a depth of 2.5 m, was clearly reconstructed as a color image averaged attenuation rate of 12.6 dB/m in the soil. A plastic pipe (6.5 cm in diameter), buried at a depth of 1 m, was also imaged by the system. >
20 citations
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