Based on the theory of the Software radio, a Digital Auto Gain Control system in the Digital IF Receiver(DIFR) is proposed in this paper, which can improve the dynamic range by the external AGC and the internal AGC. Then, The theory of the external AGC and three kinds of internal DAGC is introduced, and the simulation and the analyse result is proposed. Finally, Based on the FPGA, a low complexity implementation method of the external AGC and the internal AGC is proposed.
A novel dual-band filter of 2.8-3.6GHz and 5.0-5.8GHz is presented, based on the structure of microstrip stubs. A five-pole Chebyshev lowpass prototype with 0.1dB passband ripple is chosen to design the2.8-5.8GHz 1/4 wavelength short-circuited stubs bandpass filter. Coupling with 1/4 wavelength open-circuited stubs, the wide passband is split into two passbands. The microstrip dual-band bandpass filter is fabricated according to the simulation of ADS and HFSS, and the parameters measured match well with the simulated results.The minimum insertion loss in the first and second passbands is 1.08 dB and 1.58dB; VSWR is lower than 1.4 and1.53 in the two passbands, respectively; and the out-of-band rejection is better than 30 dB. Moreover, the proposed filter is low-cost, easy to design and realize, applicable for the radio frequency front-ends.
The main demands and real cases for space application of commercial-off the shelf(COTS) parts are reviewed. Main failure modes of electronic parts in space applications are reviewed. In addition, the differences between a typical COTS part and the corresponding high-quality-level part are analyzed. Afterwards, the main risks of space application of COTS parts are identified. For the risks, the risk mitigation measures are reviewed, and an integrated theoretical framework for risk mitigation is proposed. Some real cases of risk mitigation measures are provided as well.
In this paper, the basic theory of 2-D(azimuth and elevation) correlation interferometer is explained.And it analyzes the processing of 2-D DOA searching as an example of the 7-element array.A new methodology for 2-D parabola fitting which is based on 1-D parabola fitting is present. The simulation results show that this algorithm is effective at improving direction finding(DF) precision. It also compares the DF error with different angle steps in DF table. At last, this algorithm is applied to an actual project, and the DF precision is improved.
This paper first introduces the problem that the simultaneous communication of multiple FH nets can not be follow-on jammed by the present tactical communication countermeasures system and the reasons are analyzed, then presents the guiding method of follow-on jamming the multiple nets FH signals and the method of fast generation of multiple-frequency jamming signals which enable the tactical communication countermeasures system to simultaneously follow-on jam multiple FH nets.
Location on Time Difference of Arrival(TDOA) with four satellites had high-precision without any other constraint. This paper discussed the TDOA theory with four geosynchronous satellites, deduced its error model, emulated the influence of location accuracy for different factors, compared the location efficiency with four low-orbit satellites. The conclusions can be a reference for high-precision location technology.
The installation of glass bead in RF coaxial connectors on a microstrip line(ML) has an important effecton thevoltagestandingwaveratio(VSWR). Inthispaper,VSWRperformanceofdirectinstallation,connecting bysolders,andribbonbondingoverthefrequencybandof1-30GHzisdiscussedusingHFSSSoftware.Indesign,by changing the length and impedance of hard coaxial line, thickness of solders, width of ribbon, space between ribbonandcavitywall,andinnerradiusofribbon, the best installation for 2.0 mm×1.6 mm×0.3mm glass bead isachieved. Using ribbon bonding with 0.7mmwidth and 20μmthickness, when thelength of 50 Ω hard coaxiallineare0.5mm, and thespacebetween ribbon and cavitywallis0.6mm, VSWR is the lowest, 1.1848.
The direction-finding of phase interferometers has a conflict between no ambiguity view angle and baseline length about antenna. This paper uses the idea of genetic algorithm to improve the calculation course of phase interferometers. And this idea can solve a part of phase ambiguity problem. In the end, the paper gives the analysis of emulational experiment.
The methods of array signal processing for dual-satellite emitter localization system in the complex electromagnetic environment are put forward. Some Monte-Carlo experiments for the estimation of TDOA/FDOA as well as DOA based on beamforming and blind source separation are given, which shows the capability in the case of weak signal and the time-frequency overlap signals. The technique of emitter localization based on is presented and the higher performance is analyzed.
Asthedevelopmentofmodern radar, communication systems, satelliteand othertechnologies, thespeed and accuracyofthedataacquisitionsystemareofever-increasingdemands.However,duetotheimpactoftheexistingdevicemanufacturingtechnology,thetraditionalstructureoftheADCislimitedinhighspeedandhighprecision.TheTime-interleavedparallelsampling(TIPS)hasprovidedavalidmethodtosolvetheproblem.Inthisarticle,the basic principles and knowledge of Time-interleaved parallel sampling are studied. Based on the theory, a ultra-high-speed acquisition card which can obtain twochannelsofspecificationsof5 GSpsand 10bit is designed.
A property evaluation method for angle tracking receivers is proposed. Based on the working principle of angle measurement receivers, the proposed method can directly evaluate the angle measurement accuracy, and simplify the index allocation process of a tracking system. Based on a practical parameter combination,a simulation evaluation study of a single-channel angle tracking receiver demonstrates the application process of the proposed method, and reveals the relationship between of the angle measurement accuracy and the signal adding and averaging time.
To solve the problem of low precision geolocation in nadir point by dual-satellites using time difference of arrival(TDOA) and frequency difference of arrival(FDOA)information, a high precision method using different orbit altitudes is presented in this paper, and emulated the influence of location accuracy for three instances. The analysis reviewed that when the two satellites located in different orbit altitudes, and their velocites met certain requirements, the precision increased in nadir point of dual-satellites.
This paper studies SpaceWire bus and designs a SpaceWire bus node applying in space systems. Simulations and prototype testing results show that the designed SpaceWire bus node can meet the required data rate.The designed SpaceWire bus node is generic in nature and the ideas herein can be used in other applications.
A crossed dipole antenna is proposed in this paper with broad beam and circularly polarized performance. The circularly polarized radiation is obtained by the orthometric dipoles with 90° phase differences,which have a self-phase shifting structure with a suitable proportion of the dipole length. The antenna's impedance is matched in a broadband by both slot coaxial line Balun and microstrip line impedance transformation. The dipoles tail end is bended to ground plane for broaden the beamwidth. For the marine satellite communication, the designed antenna operates at 1.525GHz~1.665GHz with vswr less than 1.5, AR less than 3dB and 3dB beamwidth larger than 130°.
In this paper, through to the analysis of the circuit principle of a wideband 4-way in-phase power combiner getting high balance, and analyses the design of high power combiner selection of main device, again to high power equipment is mainlypayattention tothethermal design of simulation, finally gives the power combiner design completed realphotosand testresults. Design ofphysicalobjectsthrough an airborne system VHF band 2.5kWpowercapacityverification and application in the system.
A modified differential evolution strategy(MDES) algorithm based on DES and continuous ant colony optimization(CACO) algorithm is proposed in this paper. The possibility of premature can be reduced and the convergence rate is improved. The loading location, loading resistance and reactance values of wideband omnidirectional antenna are optimized by the MDES algorithm. The optimization result shows that the antenna's gain radiation patterns are not cupped in the 20:1 frequency bandwidth, and the VSWR of antenna is less than 3.0.
Base on the multi-beam reflector antenna which equiped on the GEO satellite, The research of the technology with beamforming is implemented in this paper。Fisrtly, the model of beamforming is given, then the factors which influence beamforming are analyzed. Combinate with 25m reflector and 7 feeds antenna, this paper simulates the efficiency of beamforming. The result shows that multi-beam forming can improves the gain of multi-beam reflector antenna evidently.
Manycast is a novel network communication model integrating anycast and multicast.Manycast can be used in many application fields and has good application prospects but lots of technical problems must be solved.In this paper,basic concept and functions of manycast are introduced.Then,technical traits and problems of manycast are analyzed.Based on above explanation,various implementation methods and applications of manycast are discussed especially in wireless self-organized network.
In this paper,a kind of ultra-wideband antenna is designed which used Achimedean antenna as a radiator.The antenna impedance matched with a tapered impedance,broadband radiation pattern is achieved by optimize the reflector cavity.The operating band of the antenna for 200MHz to 1200MHz,bandwidth is 6:1, achieved the emphases band's integrated design,the antenna in the band VSWR≤2,the average gain is more than 6.6dB cover the entire frequency range,axial ratio less than 3dB,beam width is greater than 70 degress, front-to-back ratio greater than 13dB,cross-section of only 100mm.
分析了Link16数据链飞行目标节点的存量位置估计“雨图”信息特点,提出了一种基于k-Means构造最小张树的类数测算方法,并根据飞行目标节点位置估计“雨图”的不同情况,通过仿真分析给出了针对不同情况的解决办法,最后讨论了算法的使用限制条件.
