Automatic IQ Phase Calibration Design in a 2.4GHz Direct Conversion Receiver

An automatic IQ phase calibration method implemented in a 2.4GHz direct conversion receiver is proposed. It uses a delay locked loop （DLL） with a proposed quadrature phase detector to greatly reduce the phase error. The receiver is fabricated in a 0.18μm CMOS process. Measurements show that the IQ phase error can be calibrated within 1°,which satisfies the system requirement.

Joint DOA Estimation and Phase Calibration for Synchronous CDMA with Decorrelator

A joint direction of arrival (DOA) estimation and phase calibration for synchronous CDMA system with decorrelator are presented. Through decorrelating processing DOAs of the desired users can be estimated independently and all other resolved signal interferences are eliminated. Emphasis is directed to applications in which sensor phases may be in error. It is shown that accurate phase calibration in conjunction with their use in high resolution DOA estimation can be achieved for the decoupled signals.

Automatic calibration for wobble errors in shallow water multibeam bathymetries

The wobble errors caused by the imperfect integration of motion sensors and transducers in multibeam echo-sounder systems(MBES)manifest as high-frequency wobbles in swaths and hinder the accurate expression of high-resolution seabed micro-topography under a dynamic marine environment.There are many types of wobble errors with certain coupling among them.However,those current calibration methods ignore the coupling and are mainly manual adjustments.Therefore,we proposed an automatic calibration method with the coupling.First,given the independence of the transmitter and the receiver,the traditional georeferenced model is modified to improve the accuracy of footprint reduction.Secondly,based on the improved georeferenced model,the calibration model associated with motion scale,time delay,yaw misalignment,lever arm errors,and soundings is constructed.Finally,the genetic algorithm(GA)is used to search dynamically for the optimal estimation of the corresponding error parameters to realize the automatic calibration of wobble errors.The simulated data show that the accuracy of the calibrated data can be controlled within 0.2%of the water depth.The measured data show that after calibration,the maximum standard deviation of the depth is reduced by about 5.9%,and the mean standard deviation of the depth is reduced by about 11.2%.The proposed method has significance in the precise calibration of dynamic errors in shallow water multibeam bathymetrie s.

Application of modified multiple subarrays detection method to multibeam bathymetry system

Either amplitude based methods or phase based methods are usually used in multibeam bathymetry system and chosen in practical measurement by ad hoc criteria. The errors of the detection are often caused by choosing wrong detection method. In this paper a modified multiple subarrays amplitude-phase united detection method is proposed , which uses both the amplitude and phase of echo from bottom.This new method not only realizes the super-wide swath coverage, but also improves the detection performance by using the phase differences among subarrays in place of phases of subarrays to estimate the phase slope image. Experimental results are also analyzed and discussed to demonstrate the effectivity of the proposed approach.

Method for array gain and phase uncertainties calibration based on ISM and ESPRIT

A new method for array calibration of array gain and phase uncertainties, which severely degrade the performance of spatial spectrum estimation, is presented. The method is based on the idea of the instrumental sensors method （ISM）, two well-calibrated sensors are added into the original array. By applying the principle of estimation of signal parameters via rotational invariance techniques （ESPRIT）, the direction-of-arrivals （DOAs） and uncertainties can be estimated simultaneously through eigen-decomposition. Compared with the conventional ones, this new method has less computational complexity while has higher estimation precision, what＇s more, it can overcome the problem of ambiguity. Both theoretical analysis and computer simulations show the effectiveness of the proposed method.

Impact of Phase Noise on TDMS Based Calibration for Spaceborne Multi-Beam Antennas

For spaceborne multi-beam antennas(MBAs), time division multiplexed switching(TDMS) based calibration receiver can reduce implementation costs effectively and is very suitable for large-scale applications. However, in practice, random phase noise imposed by noisy local oscillators can cause significant performance degradation in TDMS-based calibration systems. Characterization of phase noise effects is therefore crucial for practical applications. In this paper, we analyze the impact of phase noise on the calibration performance for a MBA system. Specifically, we derive the relationship between the probability of correct amplitude/phase estimation and various practical factors involving the signal-to-noise ratio(SNR), the standard deviation of phase noise, the given tolerance region, and the length of the spreading code. The results provide high efficiency for evaluating the calibration performance of the MBAs based on TDMS, especially for precisely anticipating the impact of phase noise. Finally, the accuracy of the derived results is assessed by simulations in different scenarios.

A Precise Calibration Method on Phase Center of Uplink Antenna Array Considering Its Actual Pointing

With regard to the inferior techniques and low accuracy of phase center calibration of an antenna array, this paper proposes a new calibration method considering the actual antenna pointing by introducing a precise engineering surveying technique to measure the real state of antennas. First, an industrial photogrammetric system is utilized to obtain the coordinates of points on antenna panels in different postures, and the actual pointing of the mechanical axis is obtained via least-squares fitting. Then, based on this, the coordinates of antenna rotation center are obtained by seeking the intersection of mechanical axes via using the matrix method. Finally, the mechanical axis in arbitrary postures is estimated based on the inverse-angle weighting interpolation method, and the reliable phase center is obtained by moving a fixed length from the projective center along the mechanical axis. An uplink antenna array including three ? 3 m antennas is taken as experimental object, and all photogrammetric coordinate systems are unified by the engineering control network, with each antenna phase center precisely calibrated via the proposed method. The results of electrical signal synthesis indicate that this method can effectively overcome the influence of gravity deformation and mechanical installation error, and enhance the synthetic signal magnitude of the uplink antenna array.

Experimental demonstration of a fast calibration method for integrated photonic circuits with cascaded phase shifters

With the development of research on integrated photonic quantum information processing,the integration level of the integrated quantum photonic circuits has been increasing continuously,which makes the calibration of the phase shifters on the chip increasingly difficult.For the calibration of multiple cascaded phase shifters that is not easy to be decoupled,the resources consumed by conventional brute force methods increase exponentially with the number of phase shifters,making it impossible to calibrate a relatively large number of cascaded phase shifters.In this work,we experimentally validate an efficient method for calibrating cascaded phase shifters that achieves an exponential increase in calibration efficiency compared to the conventional method,thus solving the calibration problem for multiple cascaded phase shifters.Specifically,we experimentally calibrate an integrated quantum photonic circuit with nine cascaded phase shifters and achieve a high-precision calibration with an average fidelity of 99.26%.

A High Phase Accuracy and Low Amplitude Mismatch Quadrature LO Driver

A 1.1 - 1.2GHz CMOS high phase accuracy,low amplitude mismatch quadrature LO driver is presented,which consists of a high frequency amplifier,an integrated poly phase filter, and an I/Q phase and magnitude calibration circuit（PMCC）. The proposed PMCC uses a feed-forward calibration technique. It improves the phase accuracy and reduces the amplitude mismatch with low power consumption. Simulation results show that phase error with PMCC is reduced to about one half and the amplitude mismatch is reduced to about one tenth, when compared to the LO driver without PMCC. Moreover,the calibration circuit also functions as a buffer to drive mixers, thus no additional buffer is needed in this design. The LO driver is implemented in a TSMC 0.25μm CMOS process. Experimental results show that the LO driver achieves high quadrature accuracy （〈2°） and low amplitude mismatch （0. 1%）. It has about 5.25dB gain and dissipates 6mA from the 2.5V power supply. The size of the die area is only 1.0mm×1.0mm.

A pressure calibration method for a portable wide-access “panoramic” cell

A simple and convenient pressure calibration method is developed for a newly designed portable wide-access ＇panoramic＇ cell. This cell is adapted to angle-dispersive-mode high-pressure in situ neutron diffraction of reactor neutron sources. This pressure calibration method has established a relationship between the cell pressure and the anvil displace- ment （gasket compression） based on the fixed-point calibration technique. By employing TiZr gasket with a thickness of 3 mm and WC anvil with a culet of 4 mm diameter, the average anvil displacements are 1.31 mm and 2.22 mm for Bi phase transitions （2.55 GPa and 7.7 GPa）, and 1.85 mm for Ba phase transitions （5.5 GPa）, respectively. In this pressure range, the pressure increases quickly with decreasing gasket thickness, and undergoes a linear increase with the anvil displacement. By extrapolating the calibration curve, the cell pressure will achieve 10 GPa when the anvil displacement is around 2.5 ram.

2.7-4.0 GHz PLL with dual-mode auto frequency calibration for navigation system on chip

A 2.7-4.0 GHz dual-mode auto frequency calibration(AFC) fast locking PLL was designed for navigation system on chip(SoC). The SoC was composed of one radio frequency(RF) receiver, one baseband and several system control parts. In the proposed AFC block, both analog and digital modes were designed to complete the AFC process. In analog mode, the analog part sampled and detected the charge pump output tuning voltage, which would give the indicator to digital part to adjust the voltage control oscillator(VCO) capacitor bank. In digital mode, the digital part counted the phase lock loop(PLL) divided clock to judge whether VCO frequency was fast or slow. The analog and digital modes completed the auto frequency calibration function independently by internal switch. By designing a special switching algorithm, the switch of the digital and analog mode could be realized anytime during the lock and unlock detecting process for faster and more stable locking. This chip is fabricated in 0.13 μm RF complementary metal oxide semiconductor(CMOS) process, and the VCO supports the frequency range from 2.7 to 4.0 GHz. Tested 3.96 GHz frequency phase noise is -90 d Bc/Hz@100 k Hz frequency offset and -120 d Bc/Hz@1 MHz frequency offset. By using the analog mode in lock detection and digital mode in unlock detection, tested AFC time is less than 9 μs and the total PLL lock time is less than 19 μs. The SoC acquisition and tracking sensitivity are about-142 d Bm and-155 d Bm, respectively. The area of the proposed PLL is 0.35 mm^2 and the total SoC area is about 9.6 mm^2.

Study on phase retardation characteristic of LCVR using dispersion analysis and SVM

To calibrate the phase retardance of a Liquid crystal variable retarder(LCVR),its birefringence dispersion characteristic was analyzed,and the Support vector machines(SVM) algorithm was adopted to establish the prediction model.The obtained SVM decision function was used as a part of LCVR phase retardance,which was generated by the driving voltage.The experimental verification was carried out with a 568 nm laser.The results show that the deviation of the experimental value and the theoretical value is about 0.0061λ.SVM method could be used as an effective method for LCVR phase retardance characteristic calibration.

An Improved Calibration Method of Grating Projection Measurement System

In the traditional fringe projection profilometry system,the projector and the camera light center are both spatially virtual points.The spatial position relationships specified in the model are not easy to obtain,leading to inaccurate system parameters and affectingmeasurement accuracy.This paper proposes a method for solving the system parameters of the fringe projection profilometry system,and the spatial position of the camera and projector can be adjusted in accordance with the obtained calibration parameters.The steps are as follows:First,in accordance with the conversion relationship of the coordinate system in the calibration process,the calculation formula of the vertical distance from the camera light center to the reference plane and the calculation formula of the distance between the projector and the camera light center are given respectively.Secondly,according to the projector calibration principle,the position of the projector light axis perpendicular to the reference plane is gained by comparing the parallel relationship between the reference plane coordinate system and the projector coordinate system’s Z-axis.Then,in order to fulfill the position restriction that the line between the projector light center and the camera light center must be parallel to the reference plane,the camera’s spatial location is adjusted so that the vertical distance between it and the reference plane tends to that between the projector light center and the reference plane.And finally,the three-dimensional(3D)reconstruction of the target object can be finished using the phase height model’s system parameters once the aforementioned position limitations are put into practice.Experimental results demonstrate that the method improves the measurement accuracy,and verifies that it is effective and available in 3D shape measurement.

Calibration and Validation of the GR2M Hydrologic Model in the Kouilou-Niari Basin in Southwestern Congo-Brazzaville

The hydrologic simulation of a catchment area, described as the transformation of rainfall into runoff, generally uses hydrologic model. This work opts for the global conceptual hydrologic model GR2M, a monthly time step model, to study the Kouilou-Niari basin, the second most important ones of the Republic of Congo. This includes two parameters to model the hydrologic behavior of a catchment area. The choice of the conceptual model GR2M is justified by the reduced number of parameters and the monthly time scale. The objective of this study is to determine the characteristic parameters of the GR2M model, by a calibrating and a validating procedure. The use of these parameters enables to follow the evolution of the water resources from the climatic variables. It has been first carried out a characterization of some physical, geological and climatic factors governing the flow, by dealing with the main climatic variables which constitute the inputs of the hydrologic model. Then, a hydrologic rainfall-runoff modeling allows to calibrate and validate the model at monthly time scale. Taking into account the number of parameters involved in hydrologic processes and the complexity of the cathment area, this model gives acceptable results throughout the Kouilou-Niari basin. The values of the Nash-Sutcliffe criterion and those of the correlation coefficient obtained are greater than 80% in validation, which explains the performance and robustness of the GR2M model on this basin.

Optimization of Multi-Level Cooperative Remote Sensing Using Carriers Flying on Counter-Phase Trajectories

The criterion for effectiveness of remote sensing system forming the image by the aim: a) further processing;b) detection of temporal changes or differences in spectral bands;accumulation and registration in GIS system is formulated. The optimal point in trajectory, where the maximum effectiveness of system’s operation of maximum information entropy at the system output is calculated. The regime limit value of parameters are calculated, upon surpassing of which the maximal effectiveness of the system may be reached.

考虑相态的垮落体材料细观参数标定方法研究——以平行黏结模型为例

基于散体力学和散体的实验室常规试验,在考虑垮落体开挖过程中煤岩颗粒呈现的多相态特征的基础上,提出结合剪切试验和颗粒柱坍塌试验的宏细观参数关系标定试验和标定方法,以颗粒流程序(particleflowcode,简称PFC)线性接触模型为例对标定试验中的各类宏细观参数关系进行了分析,并结合垮落体中救援通道开挖的相似模拟和数值模拟试验对标定方法进行了验证。结果表明:(1)剪切试验和颗粒柱坍塌试验能分别有效地反映垮落体结构在准静态流状态下的剪切破坏和垮落体在快速流状态下碰撞时的能量演变;(2)物理参数和力学参数中,摩擦系数和局部阻尼分别对处于准静态流的剪切试验和处于快速流的颗粒柱坍塌试验起主要影响作用,颗粒形态对两者的影响作用则相近且不能忽略;(3)在结合各细观参数对标定试验宏观参数的影响上,提出结合相态分析和权重分析,在确定各相态主导细观参数的基础上快速实现且满足各相态的细观参数标定;(4)采用剪切试验和颗粒柱坍塌试验标定的垮落体中救援通道开挖的数值模拟结果与相似模拟试验结果具有较高的一致性,验证了考虑相态的标定方法在垮落体研究上的可行性。

数字示波器相频特性的计量评价

针对数字示波器相频特性校准中,响应波形与激励信号之间相位差获取的难点问题,提出一种借助于脉冲沿幅度触发功能特性的方法,通过设定触发参量与激励信号幅度关系,固定与响应信号波形相对应的激励信号的相位点,从而精确获取被测数字示波器的相移特性,并统一了不同频率下相移特性的参考相位点,顺利获得数字示波器相频响应特性曲线。在一组实验中,验证了所述方法的有效性和可行性,可用于数字示波器相频响应特性的测量评价。

无线电参数综合测试平台机动伴随校准装置的测量不确定度分析

本文结合无线电参数综合测试平台机动伴随校准装置在实际应用中的情况及经验,对其本身的典型测量不确定度来源进行分析,包括频率测量、功率电平测量、相位噪声测量、衰减测量、低频信号输出频率、低频信号输出电压幅度等参数的不确定度进行了分析。

数模混合二维相控阵雷达远场收发校准方法研究

本文提出了一种基于最小系统设计准则的数模混合二维相控阵雷达远场收发校准方法,给出了实现流程、数据分析过程和实测结果。方向图的实测结果显示本文提出的校准方法得到的收发方向图主要技术指标良好且均满足使用要求,在实际工程中具有较好的操作性和推广性。

线性剪切空间调制快拍成像偏振仪动态定标数据处理技术

基于动态定标的线性剪切空间调制快拍成像测偏技术能够在动态环境(如温度变化)下对目标偏振信息进行更精确的实时测量,但实验噪声会引起反演图像的条状畸变。针对这一问题,系统分析了快拍成像偏振仪动态定标技术原理和目标相位的定量求解过程,提出了结合相位差分与双线性插值算法的噪声识别与相位修正方法。实验和计算结果表明,经过相位求解和修正计算,条带状失真得到去除,反演成像质量提升。为高相位变化和低信噪比环境下空间调制快拍成像测偏技术的实时应用提供支持,推动其在动态环境下的工程实际应用进程。