Adaptive Cancellation of Nonlinear Intersymbol Interference for Voiceband Data Transmission

Two related cancellation techniques based on "tentative" decisions are proposed for removing intersymbol interference, due to channel nonlinearities, for voiceband data transmission. Cancellation of intersymbol interference avoids the need for equalizing or "inverting" analog nonlinear operations as in the decision-feedback method previously proposed by Falconer. The nonlinear cancellation approach removes nonlinear interference terms without excessive noise enhancement and allows effective implementation with ROM's to generate the needed nonlinear signal variables that are to be weighted and summed. The first technique can be incorporated as an "add-on" unit to a present-day modem; the second technique requires a different receiver architecture but offers somewhat enhanced improvement. Simulation results for 9.6 kbit/s data transmission over nonlinear channel models show that both techniques can offer substantial performance improvements for 16-point QAM systems.     

A Hardware Efficient Passband Equalizer Structure for Data Transmission

A passband digital equalizer is proposed which combines the functions of bandpass filtering and phase splitting with that of adaptive equalization. The new equalizer also provides the in-phase and quadrature outputs required for demodulation. Although input sampling is required at several times the symbol rate (for voice-grade channel applications), outputs need be computed only once per baud. This structure economizes either on front-end analog (phase splitter) filtering or on the number of multiplications required in a digital implementation of a phase splitter and an equalizer. The performance of a receiver incorporating the new equalizer is compared, experimentally, with a receiver using a conventional fractionally spaced (T/2) equalizer.     

Rapid Training of a Voiceband Data-Modem Receiver Employing an Equalizer with Fractional-T Spaced Coefficients

Fast initial training of a voiceband data-modem receiver which employs an equalizer with fractionl-Tspaced coefficients is presented. The modem receiver performs rapid gain acquisition, and monitors the equalizer delay line for the presence of a periodic training signal whose period is equal to the length of the equalizer delay line. Testing for periodicity is combined with estimating carrier-frequency offset. Once a full period of the training signal has been obtained, the equalizer coefficients are computed by spectral division, and coefficient centering is performed. The receiver then proceeds in a reference-directed mode until the end of the training signal is detected. In the paper, algorithms for rapid gain acquisition and the detection of a cyclic training signal in the presence of noise and carrier-frequency offset are presented. Cyclic training of an equalizer with fractional-Tspaced coefficients is derived. It is shown that the equalizer coefficients can be computed efficiently by spectral division. Coefficient centering, carrier-phase and symbol synchronization, reference-directed training, and the transition to data mode are described. Finally, measurement results for an experimental 2400 baud modem using an equalizer with 64T/2-spaced coefficients are given. The modem achieves a startup time of 20 ms on a Bell 3002 unconditioned leased line.     

A Battery-Powered Digital Modem for Telephone Transmission of ECG Data

We present the design of a battery-powered digital modem for transmitting ECG signals. It operates from a 5-V battery supply, uses a coil or acoustic coupler for a telephone interface, and consumes only 30 mW during transmission. We show error rates comparable to regular stand-alone modems, well within the acceptable limit of 1 bit per 100 kbits transmitted at a transmission speed of 300 Bd.     

A Performance Study of Delta Modulation Systems for Voiceband Data Signals

In this paper the performance of delta modulation (DM) systems have been studied by computer simulation when the input signal to the DM coder is a voiceband data signal. First, the parameter values of three DM systems, linear DM (LDM), constant factor DM (CFDM), and continuously variable slope DM (CVSD) has been optimized for 4800 bits/s differential phase shift keying (DPSK) signal. Then, the performance of the three DM systems have been studied for ideal and noisy channels. It has been found that the peak signal-to-quantization-noise ratio (SQNR) is nearly the same regardless of coding scheme used, but CFDM yields the widest dynamic range. In a noisy channel, however, CFDM is very sensitive to channel bit errors. Considering the overall performance, CVSD appears to be the best among the three DM systems studied. Also, the performances of DM's have been compared with those of PCM and DPCM systems. In addition, we have studied the effect of DM quantization noise on modem bit error rate by the Monte Carlo simulation method. It is possible to transmit a 4800 bits/s DPSK signal at a bit error rate below 10^-5by CVSD with the rate of 32 kbits/s.     

A Wide-Band Passive Equalizer Design on PCB Based on Near-End Crosstalk and Reflections for 12.5 Gbps Serial Data Transmission

We propose a wide-band passive equalization method for high-speed serial chip-to-chip input/output channels using wave propagation, reflection, and coupling effects on a tightly coupled transmission line structure. This design offers precise control of wideband equalization and low-power consumption as compared to previous active and discrete passive equalizers. Significant improvements in timing jitter and voltage margin are successfully demonstrated for a data rate of 12.5 Gbps on a 40 cm long backplane printed circuit board.      

一种用于背板传输的6.25 Gbps均衡和预加重电路设计

利用0.35μm SiGe BICMOS工艺,设计了一种接收均衡和发送预加重电路。均衡部分采用2级级联的连续时间线性均衡器,补偿由于传输通道损耗带入的信号高频分量衰减。预加重部分采用了一种新型的开关电容式,电流注入结构进行比特位预加重,对高频信号进行预补偿,以降低由于信道衰减造成的ISI。测试结果显示该电路速率范围可达DC~6.25Gbps,均衡器最大可补偿-14dB@3.125GHz的信号衰减,驱动器输出预加重比例为6dB。     

一种简化的DES差分密码分析

本文简要地介绍了DES的由来和工作原理,同时给出了差分密码的分析方法,并在此基础上以6轮为例论述了如何利用差分分析方法实现DES的密码分析。     

战术数据链时隙分配协议综述

现代战场环境的复杂性决定了战术数据链时隙分配协议的多样性,而时隙分配算法对数据链系统的报文投递率、传输时延、吞吐量等性能指标有着较大的影响。针对国内外数据链网络中各种时隙分配协议进行了归纳与总结,对较为经典的固定式、争用式与动态式时隙分配协议进行了介绍,并分析了不同算法的优缺点。最后,给出了数据链网络管理系统下一步的研究方向。     

C-V2X下车载安全数据两阶段组播的中继选择与功耗分析

车载通信业务的需求加剧了基站功率消耗,降低了其数据传输的可靠性.本文提出了一种蜂窝网络下基于两阶段组播的车载安全数据传输中继选择策略,以节约系统总功耗为前提来确定中继选择范围,计算出基站功耗最小的最优组播半径x₀,并选择距最优组播半径x₀最近的车辆作为中继.基于中继的社会属性建立基站群体和中继群体间的非对称演化博弈模型,设计了不影响安全数据传输的中继娱乐数据发送功率动态再分配的奖惩机制.仿真结果表明：当车辆数目超过临界值K_min时,本文提出的中继选择策略和奖惩机制,可在保证安全数据两阶段组播可靠性的同时,使基站功耗相比直接组播的功耗至少降低25%.     

A New Architecture of a Two-Stage Lossless Data Compression and Decompression Algorithm

In this paper, we propose a new architecture for the two-level lossless data compression and decompression algorithm proposed in that combines the PDLZW algorithm and an approximated adaptive Huffman algorithm with dynamic-block exchange (AHDB). In the new architecture, we replace the CAM dictionary set used in the PDLZW algorithm with a CAM-tag-based dictionary set to reduce hardware cost and the CAM-based ordered list used in the AHDB algorithm with a memory inter-reference (MIR) stage realized by using two SRAMs. The resulting architecture is then implemented based on cell-based libraries with both 0.35- $mu$m 2P4M and 0.18- $mu$m 1P6M process technologies, respectively. With the same process technology, the prototyped chip demonstrates the new architecture not only has better performance, at least 33% improvement, but also occupies less area, only about 44%, and consumes less power, about 50%, in comparison with the architecture proposed in . In addition, the maximum data rate can achieve 2 Gbps when realizing in 0.35 $mu$ m 2P4M process technology and 4 Gbps when realizing in 0.18-$mu$m 1P6M process technology.      

IEEE 802.11 WLAN支持语音与数据业务的自适应传输方案研究

IEEE 802.11标准中的MAC协议当采用DCF和PCF时是一种随机竞争接入与轮询相结合的协议。该文通过仿真在分析研究此MAC协议对语音、数据业务综合传输性能的基础上,提出了一种支持语音与数据业务的自适应传输方案。仿真结果表明,在满足语音业务最大允许时延的前提下,自适应传输方案通过动态、合理地调整协议参数,可以提高数据业务的传输性能,从而增加网络容量。特别地,本方案不需要改动协议本身,易于实现。     

利用空闲伴音信道传输6路载波电话

本文介绍了利用一路空闲伴音信道传输６路载波电话的新方法。根据我区目前微波传输线路的传输潜力，介绍和讨论了窄带话音信号的概念和传输意义。通过运用通信系统原理，分析讨论了６路窄带话音信号的通信机理，并相应提出了伴音信道的技术要求。最后，根据实践经验介绍了调测方法。     

基于强化学习的多自由度智能超声机器人系统

超声机器人作为一种典型的医疗机器人,在辅助诊断与外科引导中可以有效提高超声成像效率并降低人工长时间操作导致的疲劳.为了提升超声机器人在复杂动态环境中的成像效率与稳定性,该文提出一种基于深度强化学习的超声机器人多自由度成像控制方法与系统.首先基于近端策略梯度优化的成像动作决策方法,实时生成超声探头空间动作和姿态运动决策,...     

非平稳信道下的鲁棒数据链优化设计综述——带限环境下的混沌传输系统

近年来,以物联网(IoT)为基础的6G的相关技术研究引起了研究单位、高校和工业界的广泛关注,其中还有一些重要的问题亟待解决。如何以较低的成本保证带限非平稳环境下数据传输的鲁棒性是一个非常重要的问题。该文介绍了一种低复杂度、低功耗的调制解调传输技术,即差分混沌键控(DCSK)调制。该文将分别描述和分析该系统在标准和非标准传输环境下的特性、优势及其改进方法。同时将提供一些基于多元DCSK(MDCSK)的新型编码调制方案来提高系统在带限环境下的传输质量,这将有助于在低功耗、低成本的网络上,特别是在非平稳信道上提升系统的鲁棒性。结果表明这些优化工作显著地改善了系统性能。之后针对非平稳信道特性系统参数的优化与自适应传输机制将成为未来研究的热点。     

一种无线数传系统设计

通过对目前几种近距离无线技术的分析比较,选用Nordic公司的nRF2401无线收发芯片和Atmel公司低功耗、高性能的8位CMOSMCUAT89C51RB2完成了近距离无线通信系统的硬件设计。该系统控制方便、工作稳定,能实现可靠的无线数据传输,可应用于无线鼠标、无线键盘、无线操纵杆、无缝接入、无线数据传输、汽车应用等...     

A New Type of Digital Filter for Data Transmission

A digital filter is introduced consisting of a transversal part and a simple recursive network. The coefficients of the transversal part are equal to integer powers of two or zero; thus complicated multipliers are avoided and instead a simple routing circuit is used. Use of several types of the recursive network makes the filter applicable in different frequency ranges. The coefficients of the transversal part can be interpreted as differences of successive values of the impulse response of the filter. It is shown that this difference routing digital filter (DRDF) is especially suited for application in data transmission.     

Fast On-Line Speech/Voiceband--Data Discrimination for Statistical Multiplexing of Data with Telephone Conversations

This paper concerns the design of a speech/data discriminator with the speed and accuracy required for statistical multiplexing of speech and high-speed baseband data on a single telephone line. The structure proposed for the discriminator combines the information from two parallel processes. The first process, even though slow, accurately recognizes the speech/data nature of the signal. This nature is determined by statistical pattern classification applied to simple zero-crossing-type parameters extracted from the signal filtered in a PCM representation. The second process has temporal accuracy in detecting transition events, from speech to data and vice versa. This detection is provided by special parameters which supply tentative transition markers. This paper applies these processes to the case of 9600 bit/s modems and describes a complete discrimination algorithm which is fit for microprocessor technology. The simulation results provided indicate a very low error rate and demonstrate that transitions are detected exactly or within one or two sampling intervals.     

一种用于海洋环境立体监测的数据传输系统

介绍了一种用于海洋环境立体监测的数据传输系统,主要从系统总体设计思路以及各部分实现方案两个方面进行了详述,该系统数据传输实时性较现有系统有所提升且使用方便,同时可对海事部门布放的原有浮标系统进行升级改造,成本相对较低,应用前景广泛。     

一种用于轨道监测系统的远距离数据传输模块设计

近年来,轨道交通监测技术更新换代的速度越来越快。为了满足各式轨道检测设施、轨道监测设备的数据处理与后续上传的客观需要,文中设计了一种远距离数据传输模块,可满足相应轨道检测与轨道监测的需要。实验表明,该模块数据传输准确,上传数据合理,可以满足在相应场景下的轨道功能需要,具有较高的实用价值。