Binary array beam forming with simulated annealing methodLi, Shikang; Xu, Xianzhe; Tao, Rentuo; Chen, Yawei
doi: 10.1117/12.2691253pmid: N/A
Binary weighted beamforming aims to achieve the optimal radiation pattern with only part of the array elements. The corresponding applications include sparse synthesis, management of aperture resources and targets allocation. However, due to the discrete weighting values as well as the corresponding non-deterministic polynomial computational complexity, most existing adaptive beamforming approaches are not suitable. Here, an algorithm based on simulated annealing optimization is proposed and the performances of binary weighted beamforming with one-dimensional and two-dimensional random arrays are numerically evaluated. According to the results with number of array elements ranging from 17 to 151, the side lobes can be reduced by 4.43 dB in average utilizing only around 66.7% of the total array elements while the width of the main lobe has increased by about 30%. For adaptive beamforming circumstances, an extra depth of up to 20 dB is achieved in presence of a preset jammer. Furthermore, a proof-of-principle optical experiment employing the spatial light modulator device is designed and studied through Huygens-Fresnel simulation.
Design of monitoring thickness and speed of cylindrical part based on laser self-mixing interference in a single-channel system during external grindingSun, Wu; Yang, Zhuo; Feng, Guo; Guo, Zeqing
doi: 10.1117/12.2691325pmid: N/A
We design a simultaneous measurement of the thickness and speed to monitor mechanical cylindrical parts during external grinding based on a laser self-mixing interference in a single-channel system. If the wavelength is modulated via the laser-injecting-current to generate a frequency shifting corresponding to the rising- and falling- edge of the triangular modulated function. The Doppler frequency caused by the cylindrical part is split into rising- and falling- edge frequencies by the frequency shifting due to wavelength variations. The expressions of the measurement are derived via the derivative of the phase’s polynomial based on the emission-intensity expressions. The frequency shifting is related to the modulation function and the thickness of the cylindrical part. The rising- and falling- edge frequencies of the laser self-mixing interference obtained from the spectrum are used for calculating the Doppler frequency and the frequency shifting for estimating the thickness and the rotation speed of a cylindrical part during external grinding and the results show a good standard derivation less than 10−3 .
Study on complex ground echo characteristics of IR-UWB fuzeLiang, Yanbin; Hao, Shijun; Liu, Chunhua; Hou, Jun; Tie, Li
doi: 10.1117/12.2691405pmid: N/A
Researching the effect of complex ground on the echo characteristics is important for impulse-radio ultra-wideband (IR-UWB) proximity fuze. In this paper, the mathematical model of mixed medium ground is established by Monte Carlo method to represent complex ground, and the time-domain signal scattering model is established based on the unit decomposition method. The correlation between echo signals of complex ground and single medium ground is studied by using this model, and the complex ground echo signal is analyzed by wavelet time-frequency transform. The simulation results show that, compared with the single medium ground, the complex ground mainly affects the peak amplitude of the echo signal, and has little influence on the peak position. The simulation and analysis provide a 1 theoretical basis for the ranging control of the IR-UWB fuze on the complex ground.
High-resolution spectral response measurement based on single sideband modulationYang, Dengcai; Feng, Lingge; Yang, Feng; Wang, Yunxin
doi: 10.1117/12.2691429pmid: N/A
The spectral response of passive optical devices reveals the important characteristics of their materials and functions and is an essential evaluation index in the development, production and application of optical devices. In this paper, a broadband and high-resolution spectral response measurement method is proposed based on single sideband modulation technology. The optical carrier emitted by the tunable light source is incident on the dual parallel Mach Zehnder modulator (DPMZM), and the Microwave signal emitted by the frequency source is loaded on the modulator. Combined with the bias voltage and the hybrid couple, carrier suppression single sideband (CS-SSB) modulation is realized. The modulated signal is received by the photodetector after passing through the passive optical device under test, and frequency of the single sideband modulated optical signal can be swept through the frequency source. This signal passes through the optical beam splitter, and the spectral response of the passive optical device is measured by the balance detection of two signals. A broadband high-resolution spectral response measurement system is constructed in the experiment. The experimental results show that the spectral measurement resolution of the system reaches at least 5 MHz, and the measurement range is 1528-1568 nm. This measurement method combines a tunable light source with a single sideband microwave photon scanning frequency. The system structure is simple, the measurement accuracy is high, and the measurement range is large. It can realize the spectrum response measurement of passive optical devices such as narrow linewidth filters and wavelength division multiplexers.
A method for generating reconfigurable photonic arbitrary phase-coded microwave signals with fundamental/double/triple carrier frequenciesYin, Jing; Zhao, Yan; Yang, Feng; Yang, Dengcai; Wang, Yunxin
doi: 10.1117/12.2691672pmid: N/A
A method for generating reconfigurable photonic arbitrary phase-coded microwave signal with fundamental/double/triple carrier frequencies is proposed and demonstrated. A dual-parallel dual-polarization Mach‒Zehnder modulator (DP-DPMZM) and an optical bandpass filter (OBPF) are cascaded to generate orthogonally polarized optical carrier signals and 1st/2nd/3rd -order sideband signals, which are sent into a polarization-dependent phase modulator (PD-PM), which can realize phase modulation with different polarization state optical signals. The phase modulated signal after PD-PM will be projected into the polarization direction with a polarizer (Pol) and the phase shifting microwave signal will be obtained with a photodetector (PD). This method enables the frequency multiplication factor to be changed by tuning the bias voltage of the modulator alone, which makes the system can work in a wide bandwidth, and it also reduces the frequency requirements of the local oscillator (LO) signal. In the simulation, binary phase-coded signals with center frequencies of 6 GHz, 12 GHz, and 18 GHz are generated, and their performance is verified.
A new spaceborne wide swath sliding spotlight mode with a high squint angleLu, Xuhang; Xu, Wei; Huang, Pingping; Tan, Weixian; Qi, Yaolong
doi: 10.1117/12.2691285pmid: N/A
The spaceborne squint sliding spotlight mode provides the capacity to observe the Earth in high resolution with different angles. However, with the increased squint angle, the imaged swath is obviously reduced due to the large range cell migration. To extend the reduced swath, a new spaceborne wide swath sliding spotlight mode with a high squint angle is proposed in this paper. Besides azimuth beam steering to improve the azimuth resolution, antenna beam is also steered in elevation to improve the swath width. The imaging principle of the proposed imaging mode is described in detail, while its corresponding flowcharts of SAR system design and imaging processing are given. Furthermore, the beam steering law of the designed system example with azimuth resolution of 0.5m and swath width of 20km is given, while the imaging result of the designed scene with three targets is given. Both simulation results validate the proposed imaging mode in the high squint case.
Sidelobe suppression in frequency diversity arc array with logarithmic frequency offsetTian, Ying; Xu, Wei; Huang, Pingping; Tan, Weixian; Gao, Zhiqi; Dong, Yifan
doi: 10.1117/12.2691333pmid: N/A
The beam scanning range of frequency diversity arc array (FDAA) has all-round advantages. When it is equivalent to a linear array, it exhibits the characteristics of "The middle spacing is large, and the spacing between the two sides is gradually reduced", and there is an inverse density weighting phenomenon, which will lead to a high sidelobe of the FDAA beam. In order to further reduce the influence of sidelobe level and inverse density weighting, the amplitude weighting is carried out on the basis of the nonlinear frequency offset of the array element, but the amplitude weighting is realized by the attenuator in each channel, which will lead to the decrease of the antenna gain, which is generally used when the radar receives the signal. For the transmitter of antenna radar, this paper proposes a phase weighting method for nonlinear frequency offset. The effectiveness of this method for sidelobe suppression is proved by simulation.
Illumination analysis and optimization for a fast detection device of lube oil wear debrisXiao, Hong; Fan, Xu; Feng, Song; Tan, Jun
doi: 10.1117/12.2691280pmid: N/A
With the development of large-scale wear debris, the demand for condition monitoring of mechanical devices increases accordingly. The fast detection device of lube oil wear debris is intended for the mechanical equipment lubricated with grease, collecting information on the abrasive particles in the equipment lubricating grease, and consequently monitor the status of the equipment. The rapid detection device needs a fitting lighting environment to collect the abrasive particle information; therefore, it is necessary to research into the lighting system of the fast detection device.
Study on influence of component parameter deviation on output signal of IR-UWB fuze receiverLiang, Yanbin; Shi, Xiaoshan; Li, Tie; Liu, Chunhua; Wu, Kaiwei; Huang, Zhonghua
doi: 10.1117/12.2691411pmid: N/A
In the actual design of the sampling integral differential circuit of the IR-UWB proximity fuze receiver, it is impossible to guarantee the complete symmetry of the circuit due to the deviation of the component parameters, which leads to the inability of the receiver to filter out the noise completely. In order to study the effect of the scattering of component parameters in the circuit on the output of noise, this paper investigates the effect of noise in the circuit on the output signal waveform of the circuit under two cases of complete symmetry and asymmetry of the circuit, based on the model of ultra-wideband fuze receiver, respectively, to provide a theoretical basis for the selection and design of ultra-wideband fuze detector devices in the future.