连续相位调制技术研究

介绍了连续相位调制(CPM)的基本原理,分析了CPM信号Laurent分解的具体过程,给出了雏特比分支度量值的实现框图和计算表达式,最后通过计算机进行仿真,得到了CPM的误码率曲线.     

连续相位调制(CPM)在战术无线通信中的应用研究

战术无线通信环境通常具有复杂多变及非视距的特征。连续相位调制由于其恒包络和带外能能量衰减快的特征,极大的提升了功放效率及频带利用率,在战术无线通信中获得了广泛的应用。本文分析了连续相位调制的技术特点,给出了在战术通信的典型应用,并展望了未来的应用前景。     

卫星通信中连续相位QPSK调制的带宽效率分析

连续相位调制(CPM)是一种带宽效率很高的调制技术,适用于卫星非线性信道。在将正交相移键控(QPSK)表示成CPM的基础上,提出了一种基于离散傅里叶变换(DFT)的谱密度计算公式。利用MATLAB的快速傅里叶变换(FFT)运算仿真了连续相位QPSK(CPQPSK)的功率谱,结果表明CPQPSK较QPSK具有更高的带宽效率。     

基于EXIT图的串行级联连续相位调制的外码设计

串行级联连续相位调制（SCCPM）系统可以大大地提高系统的功率利用率,这使得它在无线通信领域中得到广泛应用。给出了基于外信息传输（EXIT）图的SCCPM系统的收敛性能分析及外码设计,在CPM参数给定的情况下,通过EX IT图可以找出与该调制最匹配的外码。仿真结果表明：对于同一种调制不同外码的SCCPM系统,收敛的门限不同;收敛的门限越低,性能越好。     

串行Turbo编码连续相位调制

为了降低连续相位调制（CPM）系统的解调门限,减少复杂编码给系统带来的运算开销,保证系统结构简单高效,提出一种适用于CPM调制方式的串行Turbo码方案。该方案利用CPM调制本身的累加结构作为串行Turbo码的内码,利用卷积码作为外码。仿真表明,该方案的误码率优于并行Turbo编码CPM约3dB。     

连续相位调制及其捕获技术研究

以8CPM为例,阐述了连续相位调制的原理,分析了CPM信号的调制方式及其性能的优越性,具体化连续相位调制过程,明确了用DSP实现的开销及可行性。同时对CPM信号捕获的方法进行了分析研究,提出了一种确实可行的捕获方案。在Matlab仿真的基础上,用DSP硬件平台实现CPM信号的调制、发送、接收、捕获,验证了捕获方案的可行性。     

一种四进制连续相位调制新方法

为简化连续相位调制信号的相干解调,提出了一种四进制连续相位调制方法。在发送端,信号调制器根据发送的前后两组比特信息从一个预先设计的基带信号集合中选择对应的基带信号作为调制信号。该调制方法使信息码元由基带信号某一时刻的绝对相位值表示,当完成相位和载波同步后,在接收端其接收处理和传统QPSK信号一致,可以直接使用IQ路的采样值解调信息比特。仿真表明,调制信号的相干解调误比特性能与QPSK信号的相干解调相同。由于调制信号具有准恒包络和连续相位的特点,更适合应用于使用非线性功放的功率受限通信系统中。     

基于维特比算法的连续相位调制信号解调研究

文中对连续相位调制信号的解调算法作了相关研究。阐述了如何在信号状态网格图的基础上应用维特比算法对信号进行解调,并分析了最大似然序列检测和基于判决反馈的减少状态序列检测这两种序列检测方法,仿真结果表明,基于判决反馈的减少状态序列检测能在几乎不损失误码性能的前提下大大减少解调运算量。     

对具有连续相位的几种调制方式进行相频特性分析

文章以OQPSK（QPSK）为参照，对MSK（最小频移键控）、FSOQ（频移偏移正交调制）、SFSK（正弦频移键控）、IJF－OQPSK（无码间干扰无抖动正交四相相移键控）、TFM（缓变调频）及GMSK等几种具有连续相位路径的现代调制方式的相位路径和频谱特性进行了分析比较，并指出了各自的特点和适用情况。     

串行级联多指数连续相位调制的迭代检测

针对多调制指数连续相位调制(Multi-h CPM)信号给出了卷积编码、随机符号交织器串行级联系统的迭代检测,研究了针对Multi-h CPM信号的逐符号最大后验概率(MAP)检测算法及不同系统参数下的迭代检测性能。最后提出在频率脉冲截断(FPT)的基础上使用奇异值分解(SVD)的联合降复杂度算法,有效简化了部分响应多指数CPM信号的状态转移网格以及接收端的匹配滤波器。在高斯白噪声信道下,针对第二代遥测新体制(Tier2)信号进行仿真,与相同码率及码长的低密度奇偶校验(LDPC)编码系统相比,串行级联系统有着3.5 dB的性能增益。最后采用本文提出的联合降复杂度算法,能够将Tier2信号的网格状态数由256简化到64,匹配滤波器个数由64降到2,而由此带来的迭代检测性能损失却可以忽略不计。     

EDGE中8PSK调制的软件实现*

EDGE作为GSM增强数据速率演进系统,其关键技术之一是引入具有更高调制速率的8PSK调制。EDGE中8PSK调制不同于一般8PSK调制,它采用的脉冲成型滤波器是对GMSK进行Laurent分解获得的线性GMSK脉冲,且采用硬件电路实现。硬件实现Laurent分解及成型滤波存在电路成本高、灵活性差、精度低、结构复杂等缺点。针对EDGE中硬件实现8PSK的这些缺点,提出一种易于软件实现的数字信号处理算法。该算法利用正交调制实现方式与软件无线电技术,可在通用编程硬件平台上软件实现8PSK调制,具有可移植性、易实现性、成本低等优点,可用于GSM增强数据速率演进系统中。本文网络版地址：http：//www.eepw.com.cn/article/170159.htm     

Continuous Phase Modulation of F-QPSK-B Signals

A continuous phase modulation (CPM) implementation alternative of a recently standardized class of Feher-patented quadrature phase-shift keying (F-QPSK-B) modulation is proposed. Based on the fact that the F-QPSK-B signal has a quasi-constant envelope and continuous phase characteristics, it is shown that it can indeed be generated by the CPM scheme. For example, an F-QPSK-B signal can be fully generated using an existing FM-based transmitter with a modulation index of 0.5. Furthermore, a premodulation filter and an alternating change monitor differential encoder for the continuous-phase-modulated F-QPSK-B signal to be fully compatible with the I/Q modulated F-QPSK-B signal are proposed, allowing direct symbol-by-symbol coherent detection without the use of any special decoding schemes inherent in all CPM schemes. It is shown that the power spectral density and eye diagram of the continuous-phase-modulated F-QPSK-B signal are practically the same as those of the I/Q modulated F-QPSK-B signal. By utilizing CPM characteristics, an optimum maximum-likelihood (ML) coherent receiver for the F-QPSK-B signal is proposed. It is shown that the bit-error-rate performances of the optimum ML coherent detection, symbol-by-symbol coherent detection, and noncoherent detection of the continuous-phase-modulated F-QPSK-B signal are almost the same as those of the I/Q modulated F-QPSK-B signal     

基于8PSK的MLC-STBC在瑞利衰落信道中的性能

文章提出了在瑞利信道中,8PSK调制模式下多级编码空时分组编码级联的MLC-STBC方案,并在系统码率为2.032bit/s、发射天线为2、接收天线数目为1的条件下,分别对多级编码和MLC-STBC级联编码进行了仿真。仿真结果表明,基于8PSK,在瑞利衰落下利用旋转距离度量规则选择分量码码率的MLC-STBC系统,能获得比较理想的系统增益。     

Robust Time and Phase Synchronization for Continuous Phase Modulation

A novel joint timing and phase-recovery technique is proposed for continuous phase modulation (CPM) systems based on Kalman filtering and an approximate representation of CPM signals with nonorthogonal exponential expansions (nOEE). Compared with existing techniques, the proposed synchronizer requires a less complex front-end processor, and can achieve reliable acquisition performance with a shorter preamble. The asymptotic stability and convergence of the proposed synchronizer is analyzed, including the effect of statistical channel-modeling errors on the convergence characteristics. The selection of suboptimal nOEEs and the design of triple-initialized Kalman filters are also discussed. Both theoretical and simulation results show that the proposed synchronizer is robust in acquiring and tracking both the time shift and the phase offset on either time-invariant or time-variant channels.     

Convolutional Coding Combined with Continuous Phase Modulation

Background theory and specific coding designs for combined coding/modulation schemes utilizing convolutional codes and continuous-phase modulation (CPM) are presented. In this paper the case ofr = 1/2coding onto a 4-ary CPM is emphasized, with short-constraint length codes presented for continuous-phase FSK, double-raised-cosine, and triple-raised-cosine modulation. Coding buys several decibels of coding gain over the Gaussian channel, with an attendant increase of bandwidth. Performance comparisons in the power-bandwidth tradeoff with other approaches are made.     

Space-Time Coded Systems using Continuous Phase Modulation

We develop space-time trellis coded (STC) schemes using continuous-phase modulation (CPM). We employ the Rimoldi model of CPM to create a decomposed model of STC-CPM. The decomposition separates the coding from the modulation. The space-time encoding and the inherent CPM encoding is combined into a single trellis encoder on the ring of integers modulo-. This is followed by a bank of memoryless modulators. The model allows the search for good space-time codes to take into account the inherent encoding of the modulation.     

数字视频相移键控调制度技术

为避免数字电视信号在传输过程中引起波形失真并产生相互干扰 ,必须用数字信号对载波进行调制。目前 ,最常用的调制方式是相移键控调制。对其调制技术作了重点介绍。     

突发传输模式下8DPSK的位同步及相位跟踪

介绍了突发传输模式下,8DPSK解调中的位同步盲估计算法和相位跟踪算法。采用盲估计算法,能够保证高传输效率;对相位进行跟踪,可以解决频偏校正不准确而造成的相位误差积累问题。在文章的最后,还给出了matlab的仿真结果。     

一种新型FSK/PSK信号的PSK序列研究

复合调制信号由于其优异的性能,近几年成为许多学者的一个重要研究课题.基于对复合调制信号自相关函数特征的详细理论推导和分析,从高分辨率角度出发,研究了不同PSK调制对FSK/PSK信号分辨率的影响.在未引入旁瓣抑制网络情况下,获得了一种均匀二相编码与Barker码扩展序列组合的新型PSK调制方式,能较大地降低FSK/PSK信号的旁瓣.理论分析和计算机仿真表明:这种新型的复合调制方式可使旁瓣值达到-32.12 dB.这对通信系统、雷达以及信息安全等方面信号调制方式的选取有着重要的参考意义.     

Efficient Discriminator Detection of Partial-Response Continuous Phase Modulation

The aim of this work is to investigate frequency discriminator detection for continuous phase digital modulation (CPM) in order to avoid the RF carrier recovery problem. An efficient demodulation scheme, based on a discriminator followed by a suitable baseband digital processor of acceptable complexity, is presented. The baseband processoris based on decision feedback and correlation. In the binary case we also derive a simplified scheme with good performance.