The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
This paper presents a diode-based two-branch predistortion circuit. The predistortion circuit contains two nonlinear branches, including the main branch and the auxiliary branch. The main branch is a diode based nonlinear generator. The auxiliary branch consists of variable attenuator and nonlinear generator. By adjusting the voltage bias of nonlinear generator and variable attenuator, different combinations...
We consider the problem of SAR imaging with frequency band gaps. Frequency gaps in the phase history data can cause severe degradation of image quality. In this paper, we apply sparse regularization methods to reconstruct SAR images from frequency-gapped data. Two regularization methods are evaluated, i.e., the li regularization method and the sparse maximum a posteriori (SMAP) estimation method....
Clutter map constant false alarm rate (CFAR) detectors have been utilized in radar systems, which usually uses local threshold estimates from background observations to maintain CFAR level. However, when the local observations contain irrelevant information and/or heavy clutter, its detection performance would be severely degraded. To solve the problem in that clutter-dominated environment, a biparametric...
Safe landing of the plane on time is of notable importance for airport, while the current landing system of civil airplanes mainly rely on the pilot's observation of runway and aviation skills, which is disturbed by the weather. This paper presents a Landing-Aid Radar sys-tem with dual-GPU processor to use different methods to process different types of data, providing an ameliorative method for improving...
Inverse synthetic aperture radar (ISAR) images are frequently used in target classification and recognition applications. If we keep observing the target and consecutively generate multiple ISAR images, the target image varies considerably due to the motion of the target. In this paper, we propose a new ISAR system with three receivers. The phases measured from two orthogonal baselines are used to...
The background ionosphere has a great influence on the phase of echoes in geosynchronous synthetic aperture radar (GEO SAR) due to the long integration time. This paper presents a new method to correct background ionospheric phase distortion in GEO SAR, which directly estimates of background ionosphere from optimize the coherent addition value along the range equation using the range compressed data...
This paper will address issues related to Precise Point Positioning (PPP) and perform raw observation data analysis to evaluate the specific performance of PPP based its all solutions processed by CSRS-PPP using final precise orbit and clock products from IGS. For this purpose, daily sessions of observations, at 30 seconds intervals, of five different IGS stations are processed using aforementioned...
In this paper, the radiation problem of circular waveguide is analyzed using higher-order Method of Moments (MoM). The difficulty of the problem is the lack of matched excitations and loads. The method of mode matching is used to construct ideal waveports, which can provide not only excitations as sources but also perfectly matched loads. The involvement of Bessel functions makes the circular wave...
The operational value of aircraft target information obtained from HF skywave (over-the-horizon) radar is substantially reduced when the altitude of the target is undetermined. A number of techniques for estimating altitude have been proposed, relying in each case on the interference between direct and specularly ground-reflected rays, and the resulting echo amplitude distribution in delay-Doppler...
In this paper angle measurement method of Monopulse SAR is discussed. And the processing algorithm of the angle information extraction was proposed for Monopulse SAR. The simulation results verified the theoretical analysis of the proposed algorithm. With the study in the paper theoretical basis of angle estimation in Monopulse SAR was built and could be applied widely in both civil and military fields.
In this paper, a distributed targets detection method in partially homogeneous disturbance environment is proposed. Range walking is considered in the detector based on the Rao test in the range frequency domain. The proposed distributed targets detector has constant false alarm rate (CFAR) property with respect to both the covariance matrix of the clutter and the power level. Finally, the simulation...
For long range surveillance radars, space-time coding allows to increase the time on target (for improved Doppler resolution and classification capability), while still keeping a high resolution and accuracy in angle. The key performance for such systems is the sidelobe level of the ambiguity function, for which typical requirements are below 45dB. A new approach for optimizing the sidelobes level...
Because the performance of traditional Gaussian cognitive radar(CR) system for target response varying from Gaussian will be degraded, this paper extended the Gaussian target response to arbitrary non-Gaussian target distribution. In this paper, the CR multiple hypothesis classification algorithm was used for non-Gaussian targets, and the sparse spectrum of correlated narrowband target responses was...
UHF band radar can be influenced by the electromagnetic (EM) waves radiated from the communication base stations. Polarimetric measurements and analysis of the EM waves will be helpful to grasp the multi-dimension character of the EM environment which the UHF band radar confronts. In this study, polarization statistical characterization models of the base-station signals received by UHF band radar...
Random target number, heavy clutter, and heavy target density make difficult for multiple targets tracking. Gaussian mixture Cardinalized probability hypothesis density (GM-CPHD) filter based on theory of finite set statistics can perform this tracking task while with complex computation. It is well known that the computation of square-root Kalman filter based on LDL decomposition is about the half...
It is a difficult task for an unmanned ground vehicle using regular sensor to sense obstacles in unstructured environments or out fields, especially on negative obstacle sensing. In this paper, we present an approach for negative obstacle sensing, based on ultra-wideband synthetic aperture radar (SAR) image characteristic of negative obstacle sensing. And real data on negative obstacle sensing is...
In view of the defects that low data transmission rate in integrated radar-communication system based on Linear Frequency Modulation (LFM), and integrated radar-communication system based on Orthogonal Frequency Division Multiplexing (OFDM) is sensitive to frequency shift, its orthogonality of subcarriers is also easily broken. For those problems, this paper presents a novel integrated radar-communication...
This paper presents a novel multi-resolution composite array (MRCA) based Radar for high resolution digital beamforming (DBF) with much less elements than conventional uniform linear array. An adaptive beamforming based multi-targets distinguish scheme is proposed to improve multi-targets detection ability of MRCA based radar in a wide direction region. Adaptive MRCA examples were investigated with...
This paper proposes a passive bistatic radar (PBR) configuration using digital broadcasting as an illuminator for micro-Doppler effect experiments. First, the problems caused by a typical PBR usage scenario are introduced and the corresponding signal processing techniques are presented. Then, passive radar demonstrator and the experiments are described. Last, typical experimental results are illustrated...
GPS L1C navigation signal is a representative of new system signals, whose navigation message in the IS-GPS-800 protocol is not fixed frame header structure. Because of the data has no constant frame header, traditional algorithms of frame synchronization unable to be used. Based on the characteristics of L1C signal, a common algorithm is correlation function algorithm of the overlay code. The following...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.