Beidou receiver based on anti-jamming antenna arrays with self-calibration for precise relative positioning

Unmanned aerial vehicles(UAVs)may be subjected to unintentional radio frequency interference(RFI)or hostile jamming attack which will lead to fail to track global navigation satellite system(GNSS)signals.Therefore,the simultaneous realization of anti-jamming and high-precision carrier phase difference positioning becomes a dilemmatic problem.In this paper,a distortionless phase digital beamforming(DBF)algorithm with self-calibration antenna arrays is proposed,which enables to obtain distortionless carrier phase while suppressing jamming.Additionally,architecture of high precision Beidou receiver based on anti-jamming antenna arrays is proposed.Finally,the performance of the algorithm is evaluated,including antenna calibration accuracy,carrier phase distortionless accuracy,and carrier phase measurement accuracy without jamming.Meanwhile,the maximal jamming to signal ratio(JSR)and real time kinematic(RTK)positioning accuracy under wideband jamming are also investigated.The experimental results based on the real-life Beidou signals show that the proposed method has an excellent performance for precise relative positioning under jamming when compared with other anti-jamming methods.

Cognitive anti-jamming receiver under phase noise in high frequency bands

This paper investigates the jamming sensing performance of the simultaneous transmit and receive based cognitive anti-jamming(SCAJ) receiver impaired by phase noise in local oscillators(LO) over fading channels. Firstly, energy detection(ED)based on the jamming to noise ratio(JNR) of the high frequency bands SCAJ receiver with phase noise under different channels is analyzed. Then, the probabilities of jamming detection and false alarm in closed-form for the SCAJ receiver are derived. Finally,the modified Bayesian Cramer-Rao bound(BCRB) of jamming sensing for the SCAJ receiver is presented. Simulation results show that the performance degradation of the SCAJ system due to phase noise is more severe than that due to the channel fading in the circumstances where the signal bandwidth(BW) is kept a constant. Moreover, the signal BW has an effect on the phase noise in LO, and the jamming detection probability of the wideband SCAJ receiver with lower phase noise outperforms that of the narrowband receiver using the same center frequency. Furthermore,an accurate phase noise estimation and compensation scheme can improve the jamming detection capability of the SCAJ receiver in high frequency bands and approach to the upper bound.

TIME-VARYING AR MODELING AND ADAPTIVE IIR NOTCH FILTER FOR ANTI-JAMMING DSSS RECEIVER

Using Time-Varying AR (TVAR) model and adaptive notch filter is a new method for the non-stationary jammer suppression in Direct Sequence Spread Spectrum (DSSS). The performance of TVAR model for Instantaneous Frequency (IF) estimation will be affected by some factors such as basis functions. Focusing on this problem, the optimal basis function of TVAR model for the IF estimation of the LFM signal is obtained in this paper. Besides the depth and width of notching, the phase properties of notch filter affect the Signal-to-Interference plus-Noise Ratio (SINR) of correlation output to the narrowband jammer suppression in DSSS, in response to the problem the closed solution of correlation output SINR improvement has been derived when a single frequency jammer passes through direct IIR notch filter, and its performance has been compared with those of five coefficient FIR filters. Later, a novel method for LFM jammer suppression based on Fourier basis TVAR model and direct IIR notch filter is proposed. The simulation results show the effectiveness of the proposed method.

Jamming and spoofing interferences suppression technique for satellite navigation receiver

A satellite navigation receiver that can suppress jamming interference and spoofing interference simuhaneously is designed in this paper. An anti-jamming improved constrained spacial adaptive processing algorithm in signal processing and an anti-spoofing M-estimator based extended Kalman filter algorithm in information processing are proposed respectively. Simulations of the integral designed anti-interferences satellite navigation receiver demonstrate that the designed anti-interferences receiver can suppress jamming signals efficiently （ above 40 dB） and ensure the normal reception of satellite signals while satellite signals and jamming signals have the similar direction of arrival （ almost 10° ）. The designed anti-interference receiver can effectively eliminate the influence of spoofing signals on the navigation solution accuracy and maintain high accuracy of position and velocity estimation, which improves the anti-jamming and anti-spoofing capability of the satellite navigation receiver.

卡托普利抑制试验在原发性醛固酮增多症诊断和分型以及临床转归中的应用

背景 原发性醛固酮增多症(PA)作为继发性高血压中发病率最高、心脑血管危害大但手术后治愈率高的疾病,已被各大高血压指南推荐扩大筛查、早期诊断和治疗。但该类患者的确诊、分型和治疗后临床转归判定方式繁多且存在较多争议。卡托普利抑制试验(CCT)因其便捷、安全可直接用于社区、门诊,期望CCT能对PA患者进行全程管理以改善预后。目的 探究CCT对PA的诊断、分型以及临床转归的判断能力。方法 选取2020-10-01—2022-12-30在四川大学华西医院内分泌代谢科接受内分泌性高血压病因筛查并登记的824例患者为研究对象。经筛选后最终370例患者纳入研究,其中123例原发性高血压(EH)患者纳入EH组,247例PA患者分别纳入单侧醛固酮瘤(APA)组81例、特发性醛固酮增多症(IHA)组55例和未分型PA(u-PA)组111例。比较4组间差异并绘制CCT后各指标及联合诊断PA的受试者工作特征(ROC)曲线,确定最佳截断值。其次绘制CCT后各指标诊断APA和IHA亚型的ROC曲线,计算ROC曲线下面积(AUC)评估CCT对APA和IHA的分型判断能力。最后根据术后临床结局将单侧肾上腺切除患者分为3组:未缓解组11例、临床改善组27例和临床缓解组54例,比较3组间差异并判断CCT对APA患者术后临床转归的判断能力。结果 CCT后血浆醛固酮浓度(PAC)对PA的诊断效能最高(AUC=0.921,95%CI=0.893~0.950),最佳截断值为11.7 ng/dL,灵敏度、特异度分别为84.6%和86.0%;CCT后醛固酮/肾素比值(ARR)对PA也有较好的诊断效能(AUC=0.868,95%CI=0.823~0.923),最佳截断值为2.8(ng/dL)/(mU/L),灵敏度、特异度分别为82.2%和81.0%。CCT后PAC>17.0 ng/dL可协助诊断APA亚型,CCT后PAC<11.7 ng/dL同时ARR<2.8(ng/dL)/(mU/L)的患者可排除APA亚型。在接受手术治疗的患者中,有87.2%患者经CCT后PAC<11.7 ng/dL,89.7%患者CCT后ARR<2.8(ng/dL)/(mU/L)均接近术后临床缓解水平(88.0%)。结论 CCT可全程用于PA患者的诊断、分型和临床转归评价,CCT后PAC及CCT后ARR诊断PA的最佳截断值分别为11.7 ng/dL和2.8(ng/dL)/(mU/L),也可用于APA的分型判断以及术后生化缓解的判断。CCT前采血检验临床意义小,可适当简化流程。

缓蚀剂对雷达T/R组件腐蚀行为的影响

T/R组件作为雷达系统的重要组成部分,在严酷海洋大气环境的侵蚀作用下,容易发生腐蚀,从而导致雷达系统性能下降,甚至引发故障。基于实测的某型机雷达舱环境数据,编制加速腐蚀试验环境谱,针对喷涂和未喷涂TFHS-20缓蚀剂的T/R组件开展当量加速腐蚀对比试验,并以收发通道芯片的微观腐蚀形貌、铝合金外壳蚀坑深度、T/R组件收发性能和输出功率等为指标参数,表征缓蚀剂对T/R组件腐蚀行为的影响。结果表明,TFHS-20缓蚀剂仅使T/R组件的输出功率降低0.59%~0.78%、接收增益降低0.11 dB~0.21 dB,缓蚀剂对T/R组件收发性能影响非常小。未喷涂缓蚀剂的T/R组件,在加速腐蚀试验的第4周期时,发射通道性能和接收通道功能失效;喷涂缓蚀剂的T/R组件,在加速腐蚀试验的8个周期时,接收通道功能失效。所以,TFHS-20缓蚀剂能够有效地提高T/R组件的使用寿命。

超声显微测量系统的信号激励接收方法研究

超声显微测量技术是一种广泛应用于工业、航空航天、医疗等领域的无损检测方法。为了减小对100 MHz以上高频超声激励接收仪的进口依赖,研究高频信号激励接收方法。本文超声激励电路利用三级管雪崩击穿特性,以及MARX拓扑电路的电压倍增原理,通过减小激励脉冲脉宽时间,提升带宽覆盖范围。研究了高频超声信号接收电路,并集成超声激励接收仪。研究实现了设备的国产化替代,填补国内超声领域100~500 MHz高频脉冲收发仪的空白。实验结果表明,设计产生的高频激励信号峰峰值不小于128 V、上升沿时间小于0.47 ns、脉宽小于3.5 ns,系统工作带宽覆盖500 MHz,满足高频超声测量系统的需求。

G-test在肝细胞癌筛查中的诊断价值

目的提高肝细胞癌(hepatocellular carcinoma,HCC)患者的诊断对其生存率具有重要的意义。甲胎蛋白(alpha-fetoprotein,AFP)普遍应用于HCC的筛查与诊断,但是其敏感度和特异度存在不足,因此有必要进一步筛选相关标记物提高HCC的诊断率。方法对临床诊断为HCC患者及考虑存在HCC高危因素的慢性肝病患者中,对比分析荧光毛细血管法寡糖链检测(G-test)和AFP单独或联合应用于HCC的诊断率。结果本研究共纳入73名HCC及考虑存在HCC高危因素的非HCC慢性肝病患者。经病理学或影像学联合AFP确诊HCC患者30人。受试者操作特征曲线(ROC)下面积(AUC)分析得到:单独检测G-test(AUC:0.701)和AFP(AUC:0.680)二者的敏感性无显著差异(P=0.7648)。进一步研究发现G-test联合AFP(AUC:0.698)检测的灵敏度(90.0%)和特异度(93.0%)显著高于单独AFP的检测(AUC:0.671)。结论G-test联合AFP能够提高HCC的诊断率。

不依赖位置坐标的室内Wi-Fi网络覆盖度量方法

3GPP在版本16(R16,Release 16)中升级了最小化路测(MDT,minimization of drive test)技术,提出移动终端可利用4G/5G网络自主上报Wi-Fi信号的接收信号强度指示(RSSI,received signal strength indicator),为运营商度量Wi-Fi网络的覆盖率带来了可能性。然而,现有基于MDT技术的网络覆盖度量方法严重依赖GPS提供的位置坐标,但全球定位系统(GPS,global positioning system)不能提供室内精准定位,无法用于室内Wi-Fi网络的覆盖度量。为此,提出了一种不依赖位置坐标的RSSI聚类方法,充分利用室内相近位置RSSI的统计相似性,区分不同位置的RSSI测量差异,在无位置坐标条件下准确估计出室内Wi-Fi网络的覆盖率。实验结果表明,所提方法估计的覆盖率与基于真实位置坐标测量的覆盖率相近,度量准确度明显优于现有的其他方法。

高精度导航接收机自动测试系统设计

针对现有的导航接收机测试方案误差较大、可重复性差、自动化程度低等问题,设计了高精度导航接收机自动测试系统。首先,由多体制导航信号源、高性能工控机、程控电源、网络交换机、串口服务器等组成接收机测试系统的硬件平台。其次,利用信号源仿真控制软件控制多体制导航信号源模拟产生特定的导航信号,为高精度导航接收机的测试提供仿真环境;再采用Visual Studio开发了导航终端自动测试与评估软件,提出以排序评定法和均方根评定法作为接收机定位精度的评估准则。最后,通过实验验证了测试系统工作的可靠性和稳定性,且该测试系统能够准确快速地完成对高精度导航接收机性能指标的测试。

航管应答机测试仪接收特性校准方法研究

本文介绍了航管应答机的工作原理,航管应答机测试仪作用和指标梳理。利用函数发生器、任意波发生器外触发功能模拟航管应答机测试仪的询问、应答机制,实现用通用测量仪器完成航管应答机测试仪接收指标的校准,从而解决了以往只能使用专用测试设备进行接收指标校准的问题。

Comparison and Evaluation of Several Dermatophagoides Pteronyssinus Allergen Extracts for Skin Prick Test

Objective To evaluate the significance of several Dermatophagoides pteronyssinus allergen extracts for skin prick test(SPT) in patients allergic to Dermatophagoides pteronyssinus.Methods Two hundred and nineteen patients enrolled in Peking Union Medical College Hospital underwent SPT and serum specific IgE assay to detect the Dermatophagoides pteronyssinus allergen.Three kinds of house dust mite allergen extracts were used for SPT,including the Dermatophagoides pteronyssinus extract prepared by our laboratory(group A),standardized Dermatophagoides pteronyssinus extract(group B),and mixed extracts of Dermatophagoides pteronyssinus and Dermatophagoides farinae(group C).Human serum specific IgE result was regarded as the reference standard for diagnosis of Dermatophagoides pteronyssinus allergy.The receiver operating characteristic(ROC) curve was used to evaluate the diagnostic performance of SPT with the extracts of three groups.Results SPT results showed that the median wheal diameter of group A,group B,and group C was 0.43,0.35,and 0.28 cm,respectively,with significant difference among three groups(P<0.05).The difference was significant between group A and B(P<0.01) as well as group A and C(P<0.01),but not between group B and C(P>0.05).There was no local urticaria or systemic allergic reactions following the procedure of SPT.Local reaction was observed in 5 patients and delayed reaction was in 2 patients of group A.As for group B and C,local reaction occurred in 3 cases and delayed reaction in 2 cases in each group.The area under ROC curve of SPT with extract in group A,group B,and group C was 0.765,0.801,and 0.782,respectively.Based on the detection results of serum specific IgE,the sensitivity of SPT in diagnosis of Dermato-phagoides pteronyssinus allergy with extract of group A,group B,and group C was 92.4%,87.0%,and 81.5%,and the specificity was 60.6%,73.2%,and 74.8%,respectively.Conclusion The Dermatophagoides pteronyssinus extract for SPT prepared by our laboratory offers good sensitivity and specificity comparable to commercially available allergen extracts,and it may be an appropriate candidate for clinical screening and diagnosis of Dermatophagoides pteronyssinus allergy.

多站时差定位数字接收机设计

针对多站时差定位接收系统探测精度和动态要求,文中设计一种基于确定性延迟的宽带接收机。硬件系统由基于GPS授时的确定性相位关系的时钟系统和宽带高速采集系统组成,实现300 MHz~18 GHz频段宽带信号的中频数字化接收和处理。同时,给出FPGA软件处理流程,采用信道化技术和数字视频检测技术实现对射频脉冲信号的截获和通道时间的测量。样机测试结果表明,接收机的最大瞬时带宽为200 MHz,瞬时动态超过66 dBc,综合动态大于78 dBc,延时随机误差小于100 ps,可满足多站时差定位接收系统的应用需求。

十项网络游戏障碍测验简体中文版的修订及其诊断能力评估

网络游戏障碍的诊断标准问题一直受到广泛关注。十项网络游戏障碍测验(IGDT-10)在多个国家具有较高的使用率,并且表现出良好的跨文化适用性。然而IGDT-10中文版在我国的使用率较低,其适用性也有待商榷。本研究对IGDT-10简体中文版量表的信效度进行评估,并采用潜在类别分析和受试者工作特征曲线确定了IGDT-10简体中文版的截断分数及诊断能力。结果发现,IGDT-10简体中文版具有良好的信效度及诊断能力,并且支持了DSM-5关于IGD截断分数的建议(认可五个或更多标准)。此外,本研究样本中的网络游戏障碍流行率为13.4%,且存在性别差异(男性高于女性),但不存在年龄差异。结果表明,IGDT-10简体中文版可作为评估网络游戏障碍的有效工具。

一种高动态范围自动增益控制电路设计

为使接收机在保证高灵敏度的情况下,适应接收端信号在很大范围内变化的需求,文中提出一种射频AGC和中频AGC相结合的四组AGC级联的完全反馈式AGC结构。首先阐述其设计思想并介绍关键电路与器件;其次,设计以国产集成芯片为核心器件的用于射频接收机的自动增益控制电路实现方案,通过对信道链路合理的增益分配、合理的器件选型,实现高于120 dB大动态范围的自动增益控制。采用该方案的实制品测试结果表明,其性能指标完全达到设计要求,在不同的频点都具有良好的电参数指标。文中方法能够解决大动态范围与高灵敏度、增益精确度、线性度等方面的矛盾,并克服早期接收机温度性能差、低温下易自激的问题,接收机稳定性得到显著增强;同时通过引入数字AGC思想,可应用于通信设备常规、跳频等多种工作方式。

单星测频无源定位测试评估系统设计

为测试评估单星测频无源定位星载接收机的功能与性能指标,采用实物试验与仿真技术相结合的方式设计了一款单星测频无源定位测试评估系统,该系统包括高动态信号模拟收发分系统和仿真评估分系统。高动态信号模拟收发分系统基于ADI公司AD9364 RF捷变收发器和XILINX公司Zyqn7000系列芯片研制,完成上行信号的产生与发送和上行信号的接收与信号处理;仿真评估分系统采用Visual Studio软件开发,用于实现信道数学仿真和单星测频无源定位算法测试评估。测试结果表明,该测试评估设备能够测试评估单星测频无源定位星载接收机性能指标,且可灵活配置卫星参数和信号参数,适应性强。

高频超声诊断儿童肘关节隐匿骨折的临床价值

目的 探讨高频超声诊断儿童肘关节隐匿骨折的临床价值。方法 选取2020年1月—2022年4月收治的疑似肘关节隐匿骨折患儿112例的临床资料,统计疑似肘关节隐匿骨折患儿高频超声及病理诊断结果,分析高频超声诊断儿童肘关节隐匿骨折价值,探讨高频超声和病理诊断儿童肘关节隐匿骨折部位一致性,比较肘关节隐匿骨折和无骨折患儿高频超声征象及肘前脂肪垫厚度,分析高频超声征象及肘前脂肪垫厚度诊断儿童肘关节隐匿骨折的价值。结果 以病理诊断结果为金标准,高频超声诊断儿童肘关节隐匿骨折的敏感度为87.10%(54/62),特异度为96.00%(48/50),准确度为91.07%(102/112);高频超声和病理诊断儿童肘关节隐匿骨折部位一致性的Kappa值0.961,符合率98.15%。肘关节隐匿骨折患儿高频超声检查肌肉损伤或血肿征、关节积液征、骨皮质连续性中断征、脂肪垫征阳性率及肘前脂肪垫厚度均高于或厚于无骨折患儿(P<0.01)。高频超声肌肉损伤或血肿征、骨皮质连续性中断征及肘前脂肪垫厚度诊断儿童肘关节隐匿骨折的曲线下面积均在0.7以上,具有一定诊断价值(P<0.01)。结论 高频超声诊断儿童肘关节隐匿骨折与病理诊断一致性较高,具有一定诊断价值。

大型LNG薄膜罐建设与运行关键技术

LNG接收站储罐建造目前趋于大型化,且已有正在进行新型储罐——薄膜罐的建设项目,对于薄膜罐建设与运行关键技术的研究具有重要的意义。通过对薄膜罐结构和施工工艺的分析,对比传统9%镍钢储罐,认为混凝土平整度控制(承台3 m以内,平整度≤5 mm)、正五十六边形角度控制(通过模板控制173.6°)、恒温恒湿环境要求(环境温度20~30℃,相对湿度<60%)、防潮层施工(混凝土表面粗糙度预处理75~150μm)、绝热板安装(精度控制±1.5 mm)、波纹板焊接(采用热熔焊,点焊—间断焊—连续焊)、气密测试(氨氮显影测试)等方面是薄膜罐建造过程中的关键控制点,对施工控制参数和关键技术提出参考标准。同时,通过对薄膜罐运行特有的氮气工艺系统的结构进行研究,并对氮气系统的呼吸模式和扫气模式进行了工艺流程分析,为薄膜罐氮气系统的运行提供了参考。

一种多通道相控阵接收组件自动测试系统的设计与实现

开发了一套适用于多通道相控阵接收组件测试的自动测试系统。该系统能够快速完成多通道相控阵接收组件的指标测试,并可对测试数据进行实时处理和存储,大大提高了测试效率,同时为多通道相控阵接收组件的筛选提供了重要参考。实际应用表明,该测试系统能够快速完成多通道相控阵接收组件的测试,对于提高测试效率、减少后期组件维修时间发挥了重要作用。

基于奇异值分解的接收机自主完好性监测算法

基于最小二乘法残差的接收机自主完好性监测(receiver autonomous integrity monitoring,RAIM)算法本质是一种基于伪距残差矢量的一致性监测算法,但由于残差矢量中各分量具有一定的关联性,掩饰了某些重要的不一致性信息。为了消除这种关联性,提出了一种基于奇异值分解的接收机自主完好性监测方法。在方法中利用奇异值分解对伪距观测矩阵中的观测系数矩阵进行分解,获得奇异值空间矢量和奇异值空间矩阵。基于奇异值空间矢量构造能够直接反映故障卫星偏差信息的检验统计量,从而可以简便地进行粗差监测,更好地满足完好性监测需求。鉴于实际中完好性故障包含运控系统故障、导航系统故障、信号传播异常以及地面接收处理故障等多类因素,以脉冲型和阶跃型两种故障方式进行基于奇异值分解的RAIM故障检测与识别,并开展仿真分析研究。结果表明,提出的方法能够正确检测、识别故障卫星,在特定参数下能够达到很好的故障识别率,即当误警概率设置为1×10^(-5)/h、引入阶跃故障误差为25 m时,算法能够实现98.8%的故障识别率。