GMSK调制方式的研究与应用

本文介绍了ＧＭＳＫ调制方式的特点，给出了高斯滤波器ＢＴ值与ＧＭＳＫ调制方式的性能的关系。提出了一种利用ＦＸ４８９实现ＧＭＳＫ调制解调的方法，分析了其性能。给出了ＧＭＳＫ信号的功率谱曲线，传输眼图与误比特性率性能。     

CDMA无线用户环路基站接收机的设计与实现

本文讨论了基于多进制正交调制的CDMA无线用户环路基站接收机的实现方法，给出了非相干接收的一个实现方案，进而以FPGA和DSP为载体，完成了复杂的解扩频调制和多进制调制双重调制的电路设计。实测表明，解调性能接近理论值，该成果具有重要的实用价值。     

数字滤波器组在多载波调制中的应用

介绍了用数字滤波器组实现多载波调制的原理、性能以及可能的研究方向,重点比较了用数字滤波器组实现多载波调制与用DFT实现多载波调制的性能,并给出了仿真结果。     

π/4-QPSK调制方式及其与GSMK调制方式的比较

简略介绍了QPSK，π／4－QPSK调制方式及其于此的π／4－QPSK调制方法，就π／4－QPSK的调制电路原理与实现作了概述，并针对π／4－QPSK调制方法的优点及其性能与GMSK技术进行了比较。     

CDMA针线用户环路基站接收机的设计与实现

本文讨论了基于多进制正交调制的ＣＤＭＡ无线用户环路基站接收机的实现方法，给出了非相干接收一个实现方案，进而以ＦＰＧＡ和ＤＳＰ为载体完成了复杂的解扩频调制和多进制调制双重调制的电路设计。实测表明，解调性能接近理论值，该成果具有重要的实用价值。     

用CPLD实现数字调制

分析了DDS用于调制的原理，给出了实现GMSD、π／4DQPSK和QAM等调制的多种方案，同时对其性能进行初步分析。在硬件实现上，用超大规模集成电路进行设计，从而提高了系统的可靠性、集成度和系统速度。     

离散多频音调制系统中符号间干扰的消除

介绍了用于高速率数字用户线中性能较优的数字调制技术－离散多频音调制，分析了调制原理及其实现方法，提出了加循环前缀与时域均衡器相结合的方法解决符号间干扰问题。     

一种应用于HFC网络的截短栅格编码调制

提出了一种新的截短栅格编码调制方法，用于和RS码级联以克服汇聚噪声的影响。仿真表明，与一般的栅格编码调制相比，这种截短栅格编码调制纠错性能相差不多，但后者的编译码要简单许多，易于用硬件来实现。     

基于支撑矢量机的调制制式识别算法

调制制式识别是信号自适应传输系统中的一项重要技术。研究表明，传统调制制式识别在训练样本有限情况下性能不佳。而基于支撑矢量机的调制分类器采用结构风险最小化原则，在样本有限情况下仍能达到较好性能。通过分析和研究，首次提出结合高阶累积量和多尺度小波分解两种特征的调制制式识别算法。该算法结合高阶累积量对调相信号以及小波特征量对多载波信号识别的突出优点，实现了多种信号的一步识别。通过对该算法在多种常见信号上的应用进行分析和仿真，证明其性能优于传统调制制式识别算法。     

基于AD9856的多模式通信信号的设计

通过对数字中频正交调制原理的介绍，具体分析了正交数字上变频芯片AD9856的性能特点和多模式信号的算法研究，从而方便容易地实现基于软件无线电技术的全数字调制的各种调制信号。     

用DDS实现MSK信号的调制

MSK调制是数字信号进行频带传输的一种调制方式,在应用中有多种实现方法,讨论一种基于DSP系统,利用FPGA设计接口通过DDS芯片产生MSK调制的方法,使用该方案的硬件电路简洁且易于实现调制器的小型化。     

Enhanced multiple-bit differential detection of DOQPSK

In this paper, we consider multiple-bit differential detection (MBDD) of differential offset quadrature phase-shift keying (DOQPSK) with conventional bit-wise differential encoding (DE). We propose two novel MBDD schemes that outperform Simon's MBDD and approach the performance of coherent detection (CD) as the observation window size N increases. The first scheme uses the full available detection window spanning N-1 bit intervals, and is referred to as F-MBDD. A careful bit-error rate (BER) analysis shows that a significant performance improvement can be realized by reducing the detection window size to N-3 bit intervals. The resulting improved MBDD (I-MBDD) of DOQPSK with bit-wise DE achieves a similar performance as Phoel's MBDD of DOQPSK with more complex symbol-wise DE. For both F-MBDD and I-MBDD, tight upper bounds and accurate BER approximations are derived. In addition, since the complexity per bit decision of brute-force decoding of MBDD of DOQPSK grows exponentially with N, we develop optimum and suboptimum fast decoding algorithms with complexities per bit decision of orders log(N+1) and N, respectively.     

脉冲功率放大器调制技术分析

介绍了微波固态脉冲功率放大器的工作原理、脉冲调制的实现方法,分析了栅极调制与漏极调制的实现方式和优缺点,应用GaN功率芯片设计制作出了采用漏极调制方案的脉冲功率放大器,在设计过程中介绍了高压脉冲调制的实现方案,并给出了详细的电路原理图,对如何进一步提升脉冲功放的上升/下降沿进行了分析。     

A Discretely Adaptive Delta Modulation Codec

A discretely variable slope delta modulation (DVSD) codec is described, which is suitable for integrated circuit realization. The step size is varied by a pulse number modulation method that does not require a precision digital-to-analog conversion circuit. An adaptation algorithm is discussed, taking into consideration the effect of transmission errors. The quantizer and integrator portion has been fabricated on a monolithic chip using MOS technology. Results obtained from an experimental 32 kbit/s codec demonstrate its excellent performance.     

一种双极性三元数字信号发生器的设计

双极性三元数字信号发生器应用于某通信系统中,它采用5开关H桥电路结构,通过5个开关的有序导通实现将信号传输中的普通串行数字信号转换成双极性三元数字信号的功能。采用双极性三元数字信号作为调制信号,大大提高了某通信系统的抗干扰能力,确保该通讯系统在特殊情况下的正常使用。减小双极性三元数字信号的上升沿和下降沿时间,有利于提高通信系统的通信质量。文章详细介绍了该电路的设计方法,同时对其主要性能参数——输出码的高、低电平,上升与下降时间的实现方法进行了阐述。并简述了其混合集成产品的技术性能和使用情况。     

一种基于包络检测的ASK调制解调电路设计

针对ASK数字调制方式,设计了一种基于包络检测调制解调电路。调制电路采用模拟调幅调制方法,用模拟乘法器AD734将被调制二进制数字信号和载波相乘产生调制信号实现调制。解调电路采用包络检测法,用运放LMH6658MA将正弦信号放大限幅转方波信号,用比较器整流电路对信号整流,然后用低通滤波器滤去载波,最后通过微分电路和比较器LM139对信号整形获得解调出的二进制数字信号,从而实现解调。通过Proteus对设计的电路进行仿真验证,结果证明,此电路结构简明,具有大的信号幅度、频率动态范围。     

A comparison of data modulation techniques for land mobile satellite channels

Several modulation schemes for transmitting data over land mobile satellite channels are compared using a Monte Carlo simulation. Schemes under consideration include differentially detected minimum shift keying (DMSK), differentially detected filtered offset quadrature phase shift keying (DOQPSK), and coherently detected binary phase shift keying with transparent tone-in-band processing (BPSK-TTIB). The transmission of data to and from a mobile radio, which is also capable of operating as an amplitude companded single sideband radio, is the application considered here. The nominal bit rate is 2400 bit/s, while the nominal channel spacing is 5 kHz. DOQPSK with nonredundant single-error correction (SEC) is shown to be a promising candidate. It is capable of outperforming DMSK with SEC by more than 1 dB. Techniques that send a reference signal along with a PSK signal and then perform coherent detection, such as BPSK-TTIB, are also shown to be inferior to DOQPSK with SEC for the class of channels considered here.     

A systematic realization of third-order quadrature oscillator with controllable amplitude

A systematic realization of third-order quadrature oscillator using a voltage-mode non-inverting lowpass filter and a voltage-mode inverting lossless feedback integrator is presented in this paper. The proposed circuit consists of two multiple-output differential voltage current conveyor transconductance amplifiers (MO-DVCCTAs), two grounded resistors and three grounded capacitors. The new circuit provides three quadrature voltage outputs, two high-impedance quadrature current outputs, and one high-impedance current output with controllable amplitude, simultaneously. When the input bias current of the first MO-DVCCTA is a modulating signal, the circuit can generate amplitude modulation or amplitude shift keying signals. The condition of oscillation and the frequency of oscillation can be controlled independently through grounded resistors. The proposed circuit only uses grounded capacitors and grounded resistors, which can be easily implemented as an integrated circuit. The experimental results and H-Spice simulation results are given to confirm the theoretical analysis.     

一种FM信号调制解调数字化实现方法研究

针对陆军某通信电台应用需求,本文提出了一种基于软件无线电设计思想的FM信号调制解调数字化实现方法,给出了数字化实现FM信号调制解调的原理架构及实现步骤,并与传统的模拟实现方式进行对比,最后对数字化实现过程进行了仿真验证.该方法已实际应用于项目,性能达到了军标要求.     

Amplitude Modulation by Means of Two-Dimensional Semirecursive Digital Filters

Modulation can be mathematically interpreted as a special case of two-dimensional convolution. Hence, it is possible to use two-dimensional sampled-data filter techniques for the realization of modulators in modern communication systems. The modulator structures consist of active elements and resistors only, and for that reason they are well adapted to large-scale integration (LSI) circuit design. It is shown that amplitude modulation (AM, OM, SSB, VSB) can be produced by nonrecursive, semirecursive or recursive twodimensional digital filters (also phase modulation for digital modulating signals). From the viewpoint of realization, the semirecursive modulator structures are of predominant interest. Some details are given of a simulated single-sideband data transmitter equipped with such a modulator structure.