Improvement and security analysis of multi-ring discrete modulation continuous variable quantum secret sharing scheme

In order to avoid the complexity of Gaussian modulation and the problem that the traditional point-to-point communication DM-CVQKD protocol cannot meet the demand for multi-user key sharing at the same time, we propose a multi-ring discrete modulation continuous variable quantum key sharing scheme(MR-DM-CVQSS). In this paper, we primarily compare single-ring and multi-ring M-symbol amplitude and phase-shift keying modulations. We analyze their asymptotic key rates against collective attacks and consider the security key rates under finite-size effects. Leveraging the characteristics of discrete modulation, we improve the quantum secret sharing scheme. Non-dealer participants only require simple phase shifters to complete quantum secret sharing. We also provide the general design of the MR-DM-CVQSS protocol.We conduct a comprehensive analysis of the improved protocol's performance, confirming that the enhancement through multi-ring M-PSK allows for longer-distance quantum key distribution. Additionally, it reduces the deployment complexity of the system, thereby increasing the practical value.

Deep learning algorithm featuring continuous learning for modulation classifications in wireless networks

Although modulation classification based on deep neural network can achieve high Modulation Classification(MC)accuracies,catastrophic forgetting will occur when the neural network model continues to learn new tasks.In this paper,we simulate the dynamic wireless communication environment and focus on breaking the learning paradigm of isolated automatic MC.We innovate a research algorithm for continuous automatic MC.Firstly,a memory for storing representative old task modulation signals is built,which is employed to limit the gradient update direction of new tasks in the continuous learning stage to ensure that the loss of old tasks is also in a downward trend.Secondly,in order to better simulate the dynamic wireless communication environment,we employ the mini-batch gradient algorithm which is more suitable for continuous learning.Finally,the signal in the memory can be replayed to further strengthen the characteristics of the old task signal in the model.Simulation results verify the effectiveness of the method.

Characterization of V-modules by Relative Quasi-continuity

We characterize V modules by relative (quasi )continuity of left R modules in this paper. It is shown that a left R module M is a V module if and only if every finitely cogenerated left R module in σ[M] is S ( quasi )continuous if and only if every left R module in σ[M] is S continuous, where S is the set of all simple left R modules. We also show that a left R module M is a locally noetherian V module if and only if every semisimple left R module (in σ[M]) is M injective if and only if every essential extension in σ[M] of every semisimple left R module in σ[M] is S ? 2 (quasi )continuous, where S ? 2 is the set of all semisimple left R modules.

Modified Omega-K algorithm for processing helicopter-borne frequency modulated continuous waveform rotating synthetic aperture radar data

With appropriate geometry configuration, helicopter- borne rotating synthetic aperture radar （ROSAR） can break through the limitations of monostatic synthetic aperture radar （SAR） on forward-looking imaging. With this capability, ROSAR has extensive potential applications, such as self-navigation and self-landing. Moreover, it has many advantages if combined with the frequency modulated continuous wave （FMCW） technology. A novel geometric configuration and an imaging algorithm for helicopter-borne FMCW-ROSAR are proposed. Firstly, by per- forming the equivalent phase center principle, the separated trans- mitting and receiving antenna system is equalized to the case of system configuration with antenna for both transmitting and receiving signals. Based on this, the accurate two-dimensional spectrum is obtained and the Doppler frequency shift effect in- duced by the continuous motion of the platform during the long pulse duration is compensated. Next, the impacts of the velocity approximation error on the imaging algorithm are analyzed in de- tail, and the system parameters selection and resolution analysis are presented. The well-focused SAR image is then obtained by using the improved Omega-K algorithm incorporating the accurate compensation method for the velocity approximation error. FJnally, correctness of the analysis and effectiveness of the proposed al- gorithm are demonstrated through simulation results.

Identification of linear continuous-time system using wavelet modulating filters

An approach to identification of linear continuous-time system is studied with modulating functions. Based on wavelet analysis theory, the multi-resolution modulating functions are designed, and the corresponding filters have been analyzed. Using linear modulating filters, we can obtain an identification model that is parameterized directly in continuous-time model parameters. By applying the results from discrete-time model identification to the obtained identification model, a continuous-time estimation method is developed. Considering the accuracy of parameter estimates, an instrumental variable (Ⅳ) method is proposed, and the design of modulating integral filter is discussed. The relationship between the accuracy of identification and the parameter of modulating filter is investigated, and some points about designing Gaussian wavelet modulating function are outlined. Finally, a simulation study is also included to verify the theoretical results.

SERIALLY CONCATENATED CONTINUOUS PHASE MODULATION WITH REDUCED ITERATIVE DEMODULATION AND DETECTION

A reduced state Soft Input Soft Output (SISO) a posteriori probability algorithm for Seri-ally Concatenated Continuous Phase Modulation (SCCPM) is proposed in this paper. Based on the Reduced State Sequence Detection (RSSD),it has more general form compared with other reduced state SISO algorithms. The proposed algorithm can greatly reduce the state number,thus leads to the computation complexity reduction. It also minimizes the degradation in Euclidean distance with decision feedback in the reduced state trellis. Analysis and simulation results show that the perform-ance degradation is little with proper reduction scheme.

Equalization for continuous phase modulation over frequency-selective fading channels

This paper presents an equalization algorithm for continuous phase modulation (CPM) over frequency-selective channels. A specific training sequence is first embedded in each data packet. By recursive least-squares (RLS) estimation, the channel information parameters can be acquired, and a fractionally spaced equalizer performs joint decoding and equalization. Simulation results show that the proposed algorithm can acquire the channel information parameters rapidly and accurately, and that the fractionally spaced equalizer can eliminate the intersymbol interference (ISI) effectively, and is not sensitive to timing inaccuracy, so this algorithm can be exploited for demodulation system in burst mode.

Improved dichotomous search frequency offset estimator for burst-mode continuous phase modulation

A data-aided technique for cartier frequency offset estimation with continuous phase modulation （CPM） in burst- mode transmission is presented. The proposed technique first exploits a special pilot sequence, or training sequence, to form a sinusoidal waveform. Then, an improved dichotomous search frequency offset estimator is introduced to determine the frequency offset using the sinusoid. Theoretical analysis and simulation results indicate that our estimator is noteworthy in the following aspects. First, the estimator can operate independently of timing recovery. Second, it has relatively low outlier, i.e., the minimum signal-to-noise ratio （SNR） required to guarantee estimation accuracy. Finally, the most important property is that our estimator is complexity-reduced compared to the existing dichotomous search methods： it eliminates the need for fast Fourier transform （FFT） and modulation removal, and exhibits faster convergence rate without accuracy degradation.

Multi-Branch Fractional Multi-Bit Differential Detection of Continuous Phase Modulation with Decision Feedback

Differential detection of continuous phase modulation suffers from significant intersymbol interference. To reduce bit error rate, multi-branch fractional multi-bit differential detection (MFMDD) with decision feed-back is proposed. By introducing decision feedback in multi-bit differential detected signals, severe inter-symbol interference can be removed. Simulation results show that the proposed structure can greatly im-proves the performance compared with MFMDD without decision feedback, and the performance of 9 FMDD is very near to the performance of the coherent detection.

Unbiased parameter estimation of continuous-time system based on modulating functions with input and output white noises

An efficient unbiased estimation method is proposed for the direct identification of linear continuous-time system with noisy input and output measurements.Using the Gaussian modulating filters,by numerical integration,an equivalent discrete identification model which is parameterized with continuous-time model parameters is developed,and the parameters can be estimated by the least-squares (LS) algorithm.Even with white noises in input and output measurement data,the LS estimate is biased,and the bias is determined by the variances of noises.According to the asymptotic analysis,the relationship between bias and noise variances is derived.One equation relating to the measurement noise variances is derived through the analysis of the LS errors.Increasing the degree of denominator of the system transfer function by one,an extended model is constructed.By comparing the true value and LS estimates of the parameters between original and extended model,another equation with input and output noise variances is formulated.So,the noise variances are resolved by the set of equations,the LS bias is eliminated and the unbiased estimates of system parameters are obtained.A simulation example by comparing the standard LS with bias eliminating LS algorithm indicates that the proposed algorithm is an efficient method with noisy input and output measurements.

IMAGING ANALYSIS OF FREQUENCY MODULATION CONTINUOUS WAVE SYNTHETIC APERTURE RADAR IN NEAR RANGE MODE

Frequency-Modulation Continuous-Wave Synthetic Aperture Radar(FMCW SAR)has shown great potential in the applications of civil and military fields because of its easy deployment and low cost.However,most of these work and analysis are concentrated on airborne FMCW SAR,where the characteristics of the imaging geometry and signal are much similar to that of traditional pulsed-SAR.As a result,a series of test campaigns of automobile-based FMCW SAR were sponsored by Institute of Electronics,Chinese Academy of Sciences(IECAS)in the autumn of 2012.In this paper,we analyze the imaging issues of FMCW SAR in automobile mode(named as near range mode),where a vehicle is used as moving platform and a large looking angle is configured.The imaging geometry and signal properties are analyzed in detail.We emphasize the difference of the near range mode from the traditional airborne SAR mode.Based on the analysis,a focusing approach is proposed in the paper to handle the data focusing in the case.Simulation experiment and real data of automobile FMCW SAR are used to validate the analysis.

Picosecond supercontinuum generation seeded by a weak continuous wave

We experimentally investigate the spectral details of a picosecond supercontinuum pumped at 1064 nm and seeded by a weak continuous wave （～20000 times weaker than the pulse peak power） at several power levels in photonic crystal fibers. Seeding at different wavelengths leads to different spectral details and the effects to the bandwidth of supercontinuum are also distinct. Spectra can be widened when seeded by a continuous wave at 1070 nm and narrowed by ～100 nm when seeded at 1080 nm. The influence is enhanced by increasing the average seeded power.

基于多项式Chirplet变换的线性调频引信干扰波形设计方法

针对现代战场环境下线性调频引信干扰技术的迫切需求,提出多项式Chirplet变换的方法实现低信噪比下对调频连续波无线电引信的信号参数估计,并针对调频连续波引信重构了干扰信号。基于线性小波变换原理,选取适当的核函数,将无线电引信信号经过旋转与平移操作后进行短时傅里叶变换,再利用遗传算法求得变换核的最优参数,实现对调频连续波信号的参数估计,并重构干扰信号。仿真对比结果表明,该方法可以在较低信噪比下实现对调频连续波无线电引信信号载波频率、调制周期、最大频偏等参数进行精准估计,相较于周期调制类干扰,重构干扰信号能够以更低功率对调频引信产生较好的干扰效果。

AA3连续流动分析仪驱动马达带动转轴旋转模块设计及土壤中总氮测试

针对连续流动分析仪检测土壤中总氮时遇到的问题,研制了驱动马达带动转轴旋转模块.该模块可使混合的样品、试剂和空气保持在合适的温度区间进行中和反应,以利于后期利用连续流动分析仪在最优化条件下对样品进行检测分析,可将总氮的检出限从16.4µg/L降低至10.0µg/L,从而提高连续流动分析仪对样品的分析精度.

强信号全覆盖下反射式强度型传感器信号调制设计

反射式强度型传感器在强信号全覆盖环境下常常受到干扰和影响,导致传感器信号的质量下降甚至失真,给后续的信号处理和数据分析带来了困难。对此,提出强信号全覆盖下反射式强度型传感器信号调制方法。首先,判断强信号全覆盖环境下传感器信号的稀疏性,并根据环境的干扰因素建立信号的观测矩阵,通过优化算法计算出稀疏向量的估计值,使用稀疏向量的估计值对观测信号进行补偿,得到补偿后的信号;然后,应用正交锁相放大技术,将补偿后的信号与严格正交的两路参考信号相乘,提高信噪比,获得增强后的信号;最后,利用连续相位多支路调制方法,对增强后的传感器信号展开比特信息分离、二维信号映射与载波相位调制操作,完成信号调制。实验结果表明,所提方法可扩展性强、稳定性高且抗干扰能力强。

基于可解释网络解耦表征的低成本雷达定位解算方法

为降低调频连续波(FMCW)雷达成本,同时提高定位精度,设计可解释解耦表征模型。该模型由网络解算器、虚假信号生成器以及可解释潜变量三部分组成。首先处理雷达信号获得中频频谱;然后输入到网络解算器中生成位置潜变量;再通过物理机制对潜变量进行转换,生成虚假中频信号频谱;最后,设计局部光滑损失函数对模型进行自监督训练,实现潜变量的解耦物理表征。实验结果表明:所提算法能对雷达系统频谱信号的粗粒度进行超分辨率细化,其机理能有效应对雷达系统的硬件公差、环境噪声、安装误差等问题,并可自动地训练出雷达的解算网络,从而具有大规模室内、机载联网定位的应用潜力。

基于时频域分析的车载毫米波雷达干扰抑制方法

文中针对车载调频连续波雷达之间相互干扰导致虚警和漏警的问题,提出一种在时频域基于改进经验模式分解和自回归模型相结合的干扰抑制方法。该方法首先使用经验模式分解区分出拍频信号中干扰分量主导的低阶本征模态函数,将其转换到短时傅里叶变换域后通过全局阈值方法进行干扰分量定位;其次,在时频域根据定位信息将拍频信号包含干扰的数据置零;最后,使用自回归模型对拍频信号中缺失的有用信号进行估计并插值。通过仿真和实测结果显示,该方法在精确地去除干扰分量的同时可以减少有用信号的功率损失,干扰抑制后的信号与参考信号的相关系数达到0.9697。与现有干扰抑制技术相比文中方法也体现出更优的干扰抑制性能。

基于线性调频连续波的合作式通信辐射源测距

针对加速运动目标参数估计中,离散多项式变换方法无法进行非整数估计的问题,本文提出基于瑞夫算法的离散多项式变换法和基于Chirp-Z变换的离散多项式变换法2种新型离散多项式变换算法,对加速运动目标速度和加速度进行估计,并对2种算法的估计误差和计算量进行了分析比较。结果表明:2种算法在信噪比-20 dB时均方误差开始接近克拉美罗界。基于瑞夫算法的离散多项式变换法与3次迭代基于Chirp-Z变换的离散多项式变换法均可在较低信噪比下可实现任意频率的有效估计且性能接近,二者均可实现低信噪比下速度、加速度的有效估计,但基于瑞夫算法的离散多项式变换法计算量远小于3次迭代基于Chirp-Z变换的离散多项式变换法。

调频连续波激光多路并行相干精密长度测量方法

面向航空航天等大型复杂机电系统,长度测量的需求从单独的一维位移测量发展到多目标、灵活便于拓展的多路并行测量。调频连续波激光雷达长度测量技术具备抗干扰、精度高、无合作等优势。本文基于调频连续波激光雷达技术开展多路并行相干精密长度测量方法研究,针对传统长度测量系统存在光纤色散、辅助路光纤漂移导致长度测量精度降低问题,提出一种含有氰化氢气体吸收池的三光路马赫-曾德尔干涉测量系统,在此基础上,基于光开关结构实现精密长度多路并行测量。通过精密导轨长度测量实验结果表明,提出的方法在3.6 m长度范围内标准差不超过25μm,实现了四路并行长度测量。与商用激光干涉仪测量结果比较,多路测量结果的绝对误差不超过30μm。