Beijing Key Laboratory of Embedded Real Time Information Processing Technology

Beijing, China

Beijing Key Laboratory of Embedded Real Time Information Processing Technology

Beijing, China
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Hu C.,Beijing Institute of Technology | Hu C.,Beijing Key Laboratory of Embedded Real time Information Processing Technology | Li Y.,Beijing Institute of Technology | Dong X.,Beijing Institute of Technology | Ao D.,Beijing Institute of Technology
IEEE Geoscience and Remote Sensing Letters | Year: 2016

L-band geosynchronous synthetic aperture radar (GEO SAR) images will most likely deteriorate in the presence of ionosphere scintillation interference due to the low carrier frequency of GEO SAR. Meanwhile, because of the high orbit and the long working time above the region with the active ionosphere, GEO SAR will experience ionospheric scintillation with a higher probability. To make the GEO SAR avoid being interfered by ionospheric scintillation, we propose an orbit-optimization strategy by utilizing the diurnal and geographical pattern of the ionospheric scintillation occurrence in this letter. As the equatorial region is likely to experience ionospheric scintillation during the specified time window from the early evening after sunset to midnight, the orbit can be optimized by tuning the GEO SAR orbit parameters (e.g., a proper time past perigee) to avoid imaging over the equatorial region during the specified time window. Finally, simulation is conducted to verify the effectiveness of the method under the proposed three types of GEO SAR orbits, and the corresponding effective sets of time past perigee are obtained. © 2004-2012 IEEE.


Hu C.,Beijing Institute of Technology | Hu C.,Beijing Key Laboratory of Embedded Real time Information Processing Technology | Li Y.,Beijing Institute of Technology | Dong X.,Beijing Institute of Technology | And 2 more authors.
IEEE Transactions on Geoscience and Remote Sensing | Year: 2016

An L-band geosynchronous synthetic aperture radar (GEO SAR) will be inevitably affected by ionosphere scintillation because of its low carrier frequency. Meanwhile, compared with the low Earth orbit (LEO) SAR, a higher orbit of GEO SAR makes it to have a longer integration time and a longer operation time within the susceptible regions of ionospheric scintillation. Thus, its imaging is more sensitive to ionospheric scintillation, and the corresponding degradation will have a different pattern. However, few works are focused on the quantitative analysis of the ionospheric scintillation impacts on L-band SAR. Moreover, the parameters of ionospheric irregularities utilized in the analyses are hard to be determined. In this paper, we first deduced the azimuth point-spread function with the consideration of both the amplitude and phase scintillation. Then, based on the measurable statistical parameters of ionospheric scintillation, performance specifications, including azimuth resolution, azimuth peak-to-sidelobe ratio (PSLR), and azimuth integrated sidelobe ratio (ISLR) are obtained to fully evaluate the impacts. The analysis suggests that in GEO SAR imaging, the azimuth ISLR severely deteriorates, whereas degradations of the azimuth resolution and PSLR are negligible. Finally, the simulations and a real ionospheric scintillation monitoring experiment by employing Global Positioning System satellites receivers were conducted, verifying the conclusions that the serious degraded contrast and focus quality of the images are brought by the raised azimuth ISLR. © 2016 IEEE.


Xin Z.,Beijing Institute of Technology | Xin Z.,Beijing Key Laboratory of Embedded Real Time Information Processing Technology | Tang L.-B.,Beijing Institute of Technology | Tang L.-B.,Beijing Key Laboratory of Embedded Real Time Information Processing Technology | And 2 more authors.
IET Conference Publications | Year: 2015

As the common method using JTAG to update the programs of DSP and FPGA is limited by the environment and equipment, there is a need for remote updating. This paper proposes a method based on RS-422 serial communication and HDLC protocol. Comparing with other remote updating methods, it is fast, stable and easy to be implemented. Apart from this, we design a system to verify the method. At last, we do an experiment to show the full process.


Zhao J.,Beijing Key Laboratory of Embedded Real Time Information Processing Technology | Yuan Y.,CAS Institute of Computing Technology | Wang J.,China Academy of Space Technology | Jin Y.,Beijing Key Laboratory of Embedded Real Time Information Processing Technology
IET Conference Publications | Year: 2015

Compared to the traditional SAR imaging algorithm, Back Projection(BP) algorithm is an accurate point-by-point imaging radar algorithm based on time-domain, with simple principle and without any approximation error in the imaging process. However, because of intensive computation and low efficiency, it's a new challengetostorage to capacity, throughput and processing ability of DSPs, a single DSP is not enough to meet these demands. So a parallel implementation method of BP algorithm based on TMS320C6678 DSP is proposed in this paper.We put forward a large point FFT multi-core parallel processing method on 2/4/8 cores what is frequently used in BP algorithm, and a multi-core synchronization method based on distributed memory. Finally using the measured data, we verify the parallel method can greatly enhance the multi-core parallelism, and the real-time performance of BP algorithm has been significantly improved.


Cui L.,Beijing Institute of Technology | Gao J.,Beijing Institute of Technology | Wang Z.,Beijing Institute of Technology | Yao D.,Beijing Key Laboratory of Embedded Real Time Information Processing Technology
IET Conference Publications | Year: 2015

Multi-channel phased array radar has the following advantages: detection multiple target, far work distance, antiinterference capability, and sensitive response, etc. The squint SAR (Synthetic Aperture Radar) is an effective means of detection in complex background in all-weather and all-day. Multi-channel phased array radar needs the consistency of amplitude and phase. The design of the system parameter should focus on the problem of spatial variability properties of PRF and resolution design. This paper introduces the composition analysis of multi-channel phased array radar, consistency of amplitude and phase, and the design of radar system parameters. The result of flight experimentation verifies the method of system design.


Ren X.-Y.,Beijing Institute of Technology | Ren X.-Y.,Beijing Key Laboratory of Embedded Real Time Information Processing Technology | Liu H.-B.,Beijing Institute of Technology | Liu H.-B.,Beijing Key Laboratory of Embedded Real Time Information Processing Technology | And 2 more authors.
IET Conference Publications | Year: 2015

High resolution medium penetrating imaging radar is a kind of important equipment which can be widely used in military, security, construction and other fields. For the sake of imaging the target buried in the medium fast and in high resolution, this paper analyzes the theory of high resolution medium penetrating imaging, proposes two dimensional fast scan method which combine column staggered array antenna with lead rail, presents the process of near field synthetic aperture imaging and structure of the prototype. In the end, the result of imaging test of the prototype is given. The prototype can penetrate 2.5cm board and image the small target, the imaging resolution is better than 1cm.


Jiang D.,Beijing Key Laboratory of Embedded Real Time Information Processing Technology | Long J.,Renmin University of China | Yu W.,Beijing Key Laboratory of Embedded Real Time Information Processing Technology | Jin Y.,Beijing Key Laboratory of Embedded Real Time Information Processing Technology
IET Conference Publications | Year: 2015

The fast and steady feature extraction and key point matching are key factors to SAR (synthetic aperture radar) image automatic registration algorithm. The real-time processing of the algorithm in SAR is one of the challenges that need to be solved urgently. This paper aims at improving the efficiency of the description of key point in SIFT algorithm. We implemented the rapid calculation of the feature extraction section in SIFT (scale invariant feature transform) based on embedded NVIDIA GPU-Tegra K1 by fully taking the advantages of multi-cores of GPU in parallel computing, floating point calculation, memory management, etc. And the speed ratio of the accelerated calculation of the SIFT feature reaches 5.5.


Zhang N.,Beijing Institute of Technology | Yao D.,Beijing Institute of Technology | Yao D.,Beijing Key Laboratory of Embedded Real Time Information Processing Technology | Li C.,Beijing Institute of Technology | Jing K.,Key Laboratory of Electronic and Information Technology in Satellite Navigation
IET Conference Publications | Year: 2015

Aiming at the characteristics of the airborne forwardsquint SAR imaging, a high-performance SAR real-time processing system is established in this paper. Firstly, in order to realize range cell migration correction (RCMC) accurately and range-azimuth decoupling in forwardsquint SAR imaging, a high-precision SAR imaging algorithm is used in this system, namely nolinear chirp scaling(NCS) algorithm. Secondly, the motion of airborne platform is unstable, so the weighted phase gradient autofocus (WPGA) algorithm is used for motion compensation. Finally, a real-time signal processor is designed which is based on the TMS320C6678 multi-core DSPs issued by TI. The processor satisfied the demands of SAR real-time imaging because of its powerful processing performance and high-speed data transmission ability.


Mei M.,Beijing Institute of Technology | Tian W.,Beijing Institute of Technology | Tian W.,Beijing Key Laboratory of Embedded Real Time Information Processing Technology | Yin L.,Beijing Institute of Technology | And 2 more authors.
IET Conference Publications | Year: 2015

FMCW radar with deramping technique has many advantages comparing to traditional pulse radar. But the expressing of signal error becomes more complicated. The distortions on amplitude and phase are unavoidable for wide bandwidth and wide pulse signal, which have a serious impact on the imaging quality. Aiming at the problem of signal error correction, the echo signal model of FMCW radar with amplitude-phase error was established in this paper. The analysis of error estimation and correction were investigated in detail especially for non-linear phase error. And a practical solution was presented to reduce the effects from the distortions. The processing and results were proved through theoretical derivation and simulation analysis validation. And this method has significantly improved the range resolution and calibrated the position deviation. Additionally, this algorithm has a strong practicability, due to considering both the indicator and real-time imaging processing algorithm costs.


Zeng T.,Beijing Institute of Technology | Zeng T.,Beijing Key Laboratory of Embedded Real time Information Processing Technology | Yin P.,Beijing Institute of Technology | Yin P.,Beijing Key Laboratory of Embedded Real time Information Processing Technology | And 2 more authors.
IET Radar, Sonar and Navigation | Year: 2016

As the next generation radar, although the distributed coherent aperture radar (DCAR) has been proposed and some basic works have been developed in recent years, this new radar technology has not been researched systematically. In this study, the concept and closed-loop workflow of DCAR are described in detail first. Then, the coherent parameters (CPs), which play an important role to realise full coherence in DCAR, are estimated based on orthogonal signal and coherent signal. To investigate the limits of estimation accuracy of CPs, the Cramer-Rao lower bounds are derived. The estimation values of CPs are filtered using Kalman filter to improve the estimation accuracy. In the following, the wideband full coherence technology based on stepped frequency signal is proposed to improve system robustness to time synchronisation error, which makes the DCAR technology more realisable in engineering. Furthermore, a grating lobe suppression method based on modified genetic algorithm in synthetic array pattern of DCAR is presented. Ultimately, the experiments are carried out using test system to verify the theory of wideband DCAR. © The Institution of Engineering and Technology 2016.

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