Nonlinear PSK and combined nonlinear PSK/FSK modulation

Two classes of constant envelope signals called, nonlinear PSK and combined nonlinear PSK/FSK are introduced. Nonlinear PSK signals select a constant phase angle during each interval depending on the state of the signal and the transmitted symbol. Combined nonlinear PSK/FSK signals select a linear phase variation during each interval and a discrete phase variation at the end of each interval depending on the current state and the transmitted symbol. Both classes of signals achieve the highest constraint length allowed by the number of states. The numerical results presented at preselected numbers of states show that these signals produce significantly high minimum distances. Distances higher than those found in the literature at the same number of states are reported. The spectra of nonlinear PSK signals are almost identical to the spectrum of BPSK signals, while those of combined nonlinear PSK/FSK signals are continuous but similar to that of BPSK signals     

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.     

Semianalytic BER for PSK

Semianalytic bit error rate (BER) estimation is a well-known method for evaluating the BER of a digital communication system. The main utility of the method is the significant time savings in computation relative to Monte Carlo simulation. Despite this advantage, no known reference defines the procedure for computing exact BER for M-ary phase shift keying (PSK) with ISI and AWGN using the semianalytic method. This letter defines an efficient procedure for computing exact semianalytic BER for modulation formats with circular constellations when the noise component of the decision variable has a circularly symmetric Gaussian distribution. The technique is demonstrated for 8PSK over the Digital Video Broadcasting-Satellite-Second Generation (DVB-S2) channel.     

Bandwidth Occupancy in PSK Systems

For phase-shift keying (PSK) systems a method has been presented to determine the filter parameters so that the degradation produced by the bandlimiting filters is tolerable and as many channels as possible can be accommodated in a given RF band. Thermal noise present in the system and intersymbol and interchannel interference are considered the major sources of impairment in the system, and these are the only sources of impairment considered in this paper. The method is here applied to a binary coherent PSK (CPSK) system when unequalized Butterworth and Chebyshev filters of different complexities are used as receiving filters, and suitable filter parameters have been determined.     

Carrier detection of PSK signals

This paper reports on a theoretical study of the detection of the 2f and 4f carrier components of phase-shift keying (PSK) signals produced by passing signal and noise through a nonlinear device. Unbalanced quadrature PSK (QPSK) signals, i.e., QPSK signals with unequal power in the two channels, are studied. The complete range of channel power ratio is covered, with equal emphasis on the general unbalanced case and the two limiting cases of binary PSK and (balanced) QPSK. Analytic expressions are derived for the detected SNR of carrier harmonics 2f and 4f as a function of SNR, channel power ratio, and normalized input bandwidth. The results apply equally well to PSK data signals and direct-sequence spread-spectrum signals. Measurements confirm every aspect of the theory. The least detectable signal type is balanced QPSK, which is detectable (at 4f) at a threshold SNR ranging from -2 to -13 dB as the detection process gain (chip or data rate/detection bandwidth) is varied from 40 to 80 dB     

Generalized PSK in space-time coding

A wireless communication system using multiple antennas promises reliable transmission under Rayleigh flat fading assumptions. Design criteria and practical schemes have been presented for both coherent and noncoherent communication channels. In this paper, we generalize one-dimensional (1-D) phase-shift keying (PSK) signals and introduce space-time constellations from generalized PSK (GPSK) signals based on the complex and real orthogonal designs. The resulting space-time constellations reallocate the energy for each transmitting antenna and feature good diversity products; consequently, their performances are better than some of the existing comparable codes. Moreover, since the maximum-likelihood (ML) decoding of our proposed codes can be decomposed to 1-D PSK signal demodulation, the ML decoding of our codes can be implemented in a very efficient way.     

LSB coded 8PSK signals

An 8PSK scheme with the least significant bit (LSB) Golay coded is proposed and its performance is analyzed. With hard decision decoding, the proposed scheme can achieve 1 dB asymptotic coding gain and also save 26% bandwidth, as compared with uncoded QPSK scheme     

PSK非相干差分解调

从通用正交解调的基本思想出发,提出一种PSK非相干差分解调方法,将载波频率的频偏转化为点积和差积的相位偏移,同时采用包络平方滤波的定时同步方法,因此具有很强的抗频漂能力。通过理论分析,推导出解调算法公式,给出了解调器结构,并得到解调算法的抗频漂门限。针对BPSK、DPSK、QPSK和DQPSK四种常用的PSK调制模式进行了仿真,验证了算法的正确性。     

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。     

Quality estimation of PSK modulated signals

The use of the Ka band (30/20 GHz) for satellite communication systems raises the problem of dealing with rain attenuation. A very important problem in fade countermeasure systems is the need to detect signal quality quickly and accurately. In fact, the countermeasure has to be initiated before the signal degradation effect an the bit error rate is detected by the user. This article presents an overview of different methods to evaluate signal quality, which are based on the availability of soft quantized levels of PSK demodulated signals at the receiver. It is shown that this class of methods has a good theoretical performance. Also, an innovative procedure is presented which adapts one of the methods to some existing hardware, and tunes up a set of parameters in order to compensate for the fact that the hardware is to same extent impaired     

一种程控式8PSK（调制）解调器

研制带宽效率高（η≥３ｂ／ｓ／Ｈｚ）的数字通信系统，需要高元（Ｍ≥８）调制技术。本文介绍了一种用单片机实现的程控式８ＰＳＫ（调制）解调器。其特点是设备简单、性能可靠、经济，具有较好的实用价值和应用前景。     

相移键控信号盲解调的仿真分析

对相移键控信号调制解调原理进行了分析,并对未知信号的载波频率和码速率估计方法进行了分析与比较,推导出了相移键控和振幅相移联合键控信号盲解调的公式,并结合4PSK,8PSK,16PSK和16QAM信号进行盲解调仿真,在不同信噪比下对不同类型的相移键控信号盲解调正确解调波特率的影响进行了分析,并给出了分析结果,给通信对抗侦...     

Trellis-coded 8PSK with embedded QPSK

A coded eight-phase-shift-keying (C8PSK) method is described that is characterized by a quaternary phase-shift-keyed signal embedded in the modulated sequence. This method is a double-trellis-coded modification of the well-known C8PSK and is referred to as MC8PSK. Five coded bits are generated from four user bits in a single coding step and then mapped to an 8PSK symbol followed by a QPSK symbol. Given comparable decoder or receiver complexity, the coding gains of C8PSK and MC8PSK are comparable. Advantages of MC8PSK concern carrier synchronization. With C8PSK, problems with carrier phase tracking are encountered. With MC8PSK, these can be avoided, since carrier phase control can be based on the embedded QPSK. For some codes, error-free decoding is achievable in any locking condition of a QPSK-dependent PLL (phase locked loop), making synchronization and decoding especially simple. The partitioning of the channel symbol set, the associated bit mapping, and the code design are treated in order to describe MC8PSK. Aspects of receiver synchronization are discussed for C8PSK and for MC8PSK, focusing on QPSK phase-detection principles. The implementation of a four-state MC8PSK modem for an information rate of 2.048 Mb/s is described, and experimental results demonstrating the very robust carrier synchronization are presented     

A Digital Demodulator for PSK Signals

This paper describes a digital demodulator for phase-shift-keyed (PSK) signals in which the phase difference between the received signal and a carrier reference is found by measuring digitally the time interval between the zero crossings of the signal and the reference. In the case of coherent detection the reference is locked to one of theMpossible phases of the signal. The advantage of this demodulator is that bulky low-pass filters and delay lines as well as critical threshold devices can be dispensed with. On the other hand, digital measurement of the phase and the use of a finite-width sampling window lead to degradation of the error performance. This degradation is theoretically analyzed for both coherent and phase-comparison detection. The quantizing error proves to be small enough when the phase difference is coded into a 6-b binary number, and the theoretical results are in good agreement with measurements taken from an experimental phase-comparison demodulator for fourand eight-level PSK signals. The experimental demodulator is also described in the paper.     

Microwave Phase Detectors for PSK Demodulators

The simplest circuits for microwave phase detectors and their operation are described. Approximate analytical expressions for the output characteristic of the various circuits are given. Accurate prediction of detector performance is achieved with a large-signal nonlinear analysis using simultaneously the time- and frequency-domain approach. Applying the theory developed, the effects which cause deformation of the detector characteristic are investigated. Results of practical circuits operating in the 14-GHz range are given and compared with regard to phase-demodulator applications. A low-level phase detector is presented which permits 20-dB level variation with less than 2° phase error.     

PSK通信信号的干扰算法研究

基于PSK通信信号的调制特点提出了一种高效干扰算法——相似信号干扰算法。该算法利用PSK调制方式的特点产生干扰波形,针对PSK通信信号进行干扰。分析了该算法产生的干扰信号码元与PSK通信信号码元相位对齐与否对PSK通信信号误比特率的影响。仿真结果表明,在相同信噪比和干信比的条件下,相似信号干扰算法比一些常规的干扰算法对PSK通信信号的干扰效果好。     

具有连续相位的8PSK调制

连续相位的QPSK信号具有恒定包络,解决了传统QPSK信号由于相位跳变所带来的包络起伏问题,但其频带利用率没有8PSK高,为提高频带利用率,提出了连续相位8PSK(CP8PSK)调制。本文首先利用差分编码规则来表征8PSK信号一个符号周期的相位变化,进而将其表示为连续相位调制(CPM)的形式,再使用频率脉冲对其相位进行脉冲整形,最终得到具有连续相位的CP8PSK表达式。为了降低系统的整体复杂度,本文还对CP8PSK进行了Laurent分解。根据理论分析CP8PSK信号应当具有恒定包络,而且比连续相位的QPSK调制要有更高的带宽效率和更平滑的频谱,通过MATLAB进行仿真之后,得到的CP8PSK具有恒定包络,且带宽效率在同等情况下要高于整形的交错QPSK(SOQPSK)和8PSK,频谱也更加平滑,抗误码性能与理想8PSK相比损失也不大。      

Analysis of a digital PSK modulator

This is a time and frequency domain study of an exclusive-OR gate used as a digital modulator. The output spectrum obtained has been partitioned into the desired PSK waveform, and the undesired part to be removed by the following filter. A simpler scheme of PSK generation has also been briefly discussed.     

Clock-aided carrier recovery in trellis-coded PSK

The effects of imperfect carrier phase recovery on uncoded and trellis-encoded PSK (phase-shift keying) are compared. A recently proposed clock-aided carrier recovery scheme is analyzed and compared to the standard frequency multiplication circuit. Results obtained through a combination of analysis and computer simulation compare uncoded 4-PSK with trellis-encoded 8-PSK carrying two bits per channel symbol. The quality of the recovered carrier phase is evaluated using the ratio of tone power to background. The system error probability is evaluated and used to determine how accurate the time clock recovery must be in a clock-aided carrier recovery circuit in order to outperform classical recovery systems. It is shown that if the clock recovery system is accurate enough, clock-aided carrier recovery used with coded 8-PSK can compensate for the increased sensitivity of the latter to phase errors     

Geometrically uniform multidimensional PSK trellis codes

The recently developed group theory of geometrically uniform trellis-coded modulation (TCM) is applied to the case of multidimensional PSK signal constellations. A general algorithm to construct geometrically uniform partitions of signal constellations is described and applied to multidimensional PSK signals. Examples of application to TCM employing 3*8 PSK signalling are presented.<>