Li J.,Peking University |
Li C.,Peking University |
Zhao Y.,Beijing Research Institute of Telemetry |
Chu Y.,Peking University
Applied Optics | Year: 2016
A simple experimental method to determine the overlap profile of Raman lidar is presented in this paper. Based on Mie and Raman backscattering signals and a geometrically constrained condition, the overlap profile of a Raman lidar system can be determined. Our approach simultaneously retrieves the lidar ratio of aerosols, which is one of the most important sources of uncertainty in the overlap profile determination. The results indicate that the overlap factor is significantly influenced by the lidar ratio in experimental methods. A representative case study indicates that the correction of the overlap profile obtained by this method is practical and feasible. © 2016 Optical Society of America.
Han B.,Beihang University |
Ma J.,Beijing Research Institute of Telemetry |
Li H.,Beihang University
International Journal of Control, Automation and Systems | Year: 2016
The purpose of this paper is to present our results in overcoming the influence of the nonlinear friction afforded by harmonic drive to the gimbal servo-system of double-gimbal control momentum gyro (DGCMG). The existence of compliance and oscillation inherent in harmonic drive systems, and the lack of any technical information on the internal dynamics of the transmission, make the development of friction compensation in harmonic drive system extremely challenging. In this paper, the modeling of nonlinear friction in harmonic drive gear transmission in gimbal servo-system of the DGCMG is proposed. The relationship among the nonlinear friction, the angular velocity and the angular position with an improved Coulomb-Viscous model is derived, and the experiments to identify the various parameters of the improved model are given. At last a feed-forward compensation controller based on the improved model is designed to carry out the friction compensation study. © 2016, Institute of Control, Robotics and Systems and The Korean Institute of Electrical Engineers and Springer-Verlag Berlin Heidelberg.
Pan X.,Beijing Institute of Technology |
Li X.,Beijing Research Institute of Telemetry
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011
Demodulator is a vital part for deep space telemetry system. On the condition of low signal-to-noise ratio, lower bit rate and more sorts of modulation types are used in deep space communication. Comparing with the conventional telemetry demodulator, some improved technologies are added to satisfy the requirements of deep space telemetry. An overview of the demodulation technology is provided here and key technologies applied in deep space demodulation are analyzed. The testing results of demodulator show that the demodulation loss can be lower than 0.3dB, bit synchronization and the Es/N0 estimation can be achieved correctly at less than -5dB. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
Peng Y.,Beijing Research Institute of Telemetry |
Liou W.W.,Western Michigan University |
Parker P.P.,Western Michigan University
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2011
In this paper, the free surface flow passing through a multi-layer porous medium is analyzed. An analytical model to describe the flow in multi-layer porous media driven by surface tension and vacuum pressure is proposed. The structure of the medium studied is modeled after those found in Rigid-Capillary-Press (RCP) dewatering devices. The capillary phenomenon is used in RCP to improve the water removal efficiency and the energy consumption in a paper making process. The porous medium is composed of six layers with complex woven fabric structures and pore sizes that range from 5μm to 2. mm The dewatering performance predicted by the analytical model is compared to the pilot plant experiments with good agreements. The potential of the model to be applied as a parametric optimization tool for industrial RCP porous media design is discussed. © 2011 Elsevier B.V.
Pan X.,Beijing Institute of Technology |
Chen M.,Beijing Research Institute of Telemetry
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010
In deep space communication, due to the restricted transmitted power, sharply-attenuated of signals because of long distance and all the noise in space, the received signals from the deep space have low signal to noise ratio (SNR) and high carrier phase noise. The Ultra long point FFT algorithm and binary branch acquisition technique were studied and the modified binary branch FFT acquisition method was proposed. The more flexible method has faster acquisition ability and higher detection probability. Based on the software radio technology, the hardware platform of "FPGA + DSP" was built to implement the 216 FFT using modified two-arm acquisition technique, the carrier wave acquisition and tracking were implemented on the condition of extra-low SNR and the test result indicated the method in this paper can implement the quick detection under the 16dBHz SNR or below. © 2010 Copyright SPIE - The International Society for Optical Engineering.
Xi P.,Beijing Institute of Technology |
Ming C.,Beijing Research Institute of Telemetry
Advances in Intelligent and Soft Computing | Year: 2012
Formation flying of small satellite has become research hotspot in space field today. Tracking Telemetry and Command (TT&C) is the key technology to ensure the whole formation to cooperate and self-running normally. Therefore, the TT&C system is becoming the main hitting target in the electronic warfare. This paper is to improve anti-interference ability of formation flying of small satellite, the TT&C controlling system characteristics are discussed and interference forms are provided. The methods of interference rejection are mainly studied. © 2012 Springer-Verlag GmbH.
Pan X.,Beijing Institute of Technology |
Nie Y.-P.,Beijing Research Institute of Telemetry
Binggong Xuebao/Acta Armamentarii | Year: 2011
Aimed at the high dynamic problem of GPS receivers in precise attack weapons, a GPS receiver with high order phase-lock loop is studied. The high dynamic tracking performance of a third-order loop is analyzed and the problem in tracking high dynamic GPS signals is investigated. Then, some methods are put forward to solve this problem, such as the bandwidth and the loop gain changed continuously. Simulation results show that these methods are effective.
Peng Y.Q.,Beijing Research Institute of Telemetry |
Zhao H.Q.,Beijing Research Institute of Telemetry |
Zou J.B.,Beijing Research Institute of Telemetry
IET Conference Publications | Year: 2014
For launch vehicles using the liquid hydrogen and liquid oxygen propulsion system, the autogenous pressurization and thrust augmentation system is common used to provide high pressure propellant flow. However, it is very difficult to precisely measure the flow rate of the pressurized high-speed gaseous oxygen flow. A flowmeter for the oxygen flowrate measurement in the autogenous pressurization system is introduced and its design details are given in this paper. The integrated flowmeter consists of Venturi tube, pressure sensor, temperature sensor and signal conditioner. The proposed flowmeter is able to measure the oxygen flow of 0.2~1.5kg/s with the precision of 1.5% and the gaseous temperature range from 150K to 450K.The sturcture is specifically designed to improve the strength and reliability in the high shock environment up to 5000g. Series of simulation and experiment results are reported in detail. The simulation and experiment results reported in this paper show that the proposed flowmeter is reliable and safe for precisely measuring of the gaseous oxygen flows in autogenous pressurization systems.
Xingwen D.,Beijing Research Institute of Telemetry |
Jianyong S.,Beijing Research Institute of Telemetry |
Ming C.,Beijing Research Institute of Telemetry |
Manhong L.,Beijing Research Institute of Telemetry
Proceedings of the International Telemetering Conference | Year: 2014
SOQPSK-TG is a highly bandwidth-efficient constant-envelope modulation so that it has been applied in aeronautical telemetry widely. We develop a simple detection of SOQPSK-TG which is based on a modified OQPSK detection. The simple detection has the advantages of low complexity and good performance. And it's also suitable for other varieties of SOQPSK and FQPSK.
Zhao H.C.,Nanjing University of Science and Technology |
Xu R.R.,Beijing Research Institute of Telemetry |
Wu W.,Nanjing University of Science and Technology
Electronics Letters | Year: 2011
A new kind of wideband waveguide slot array for synthetic aperture radar (SAR) is presented. Elliptical slots are first used for designing the waveguide slot antenna. An eight-element waveguide slot array operating at X-band is designed and measured. Predicted results are compared with measured data and good agreement is reported. The measured bandwidth for VSWR≤1.5 has reached 19.6. © 2011 The Institution of Engineering and Technology.