Generalized minimum shift-keying modulation techniques

The simultaneous data demodulation and phase tracking of an MSK signal using the Viterbi algorithm is described, and two variations of MSK modulation are studied. The MSK with overlay is a dual-rate modulation techniques in which low-rate and high-rate data are superimposed on an MSK signal. Here the demodulator uses the Viterbi algorithm to estimate both the low-rate and high-rate data simultaneously. The MSK with pseudorandom sequence spreading combats intentional or unintentional jamming. A simplified receiver for these spread-spectrum MSK signals is found that takes into consideration the effect of random phase perturbations. The performance of these demodulators is evaluated using transfer-function bounds for the bit error probability. For demodulation of the spread spectrum MSK signal, a simplified receiver is derived, and its performance in the presence of continuous jamming is evaluated     

A Look at Crosstalk in Quadrature-Carrier Modulation Systems

A method is presented for comparing the performance of different quadrature-carrier modulation techniques. It is based on the calculation of the mean-square crosstalk between adjacent digital communications channels. This method was used to determine the crosstalk of a number of constant envelope modulation schemes, including Staggered Quaternary Phase Shift Keying (SQPSK) and Minimum Shift Keying (MSK). The results, as have previous results, show the improved performance of MSK over SQPSK. By utilizing the general equation for mean-square crosstalk as a measure of performance, a search was made for constant envelope modulation methods with reduced crosstalk. A number of methods were found which have better mean-square crosstalk performance than MSK. Finally this paper presents a method for reducing degradation due to crosstalk by using mismatched windows in the standard correlation detector. An example of this technique for detection of MSK signals is analyzed.     

一种新型的基于块自适应滤波的MSK信号解调技术

本文针对MSK调制信号在军用和民用领域都得到了广泛应用的这一事实,首先简单地分析了MSK信号非相干解调性能和差分解调性能的不足.然后根据MSK数字调制信号的特点,将频域块自适应滤波技术和码元FFT求模判决算法相结合,提出了一种新型的MSK信号数字解调算法.最后在详细阐述新型MSK信号解调算法的基础上,利用计算机基于蒙特卡洛方法对新算法的解调性能进行了性能仿真,并对仿真结果进行了较为详细的分析.计算机仿真结果表明该新算法不仅简单有效,而且对噪声有很好的抑制作用.与经典的非相干解调和差分解调相比,该新算法具有较低的解调误比特率和较低的频偏敏感度,并且解调性能得到了明显的提高,具有一定的实际应用价值.     

软件无线电中MSK调制技术的仿真研究

研究了基于软件无线电的MSK调制系统。MSK是一种典型的恒包络调制技术,有相位连续和频带利用率比较高等优点。分析了软件无线电中上变频理论、正交调制原理、NCO原理和MSK调制。利用System Generator软件对软件无线电中的MSK进行了仿真,并对仿真结果进行了分析和总结,证明此调制系统具有良好的调制性能,此方法正确、可行。     

中频数字接收机的MSK调制解调仿真

软件无线电接收机要求解调模式灵活可变,并可通过设置参数来改变解调模式。根据自然基金项目要求,从多种经典调制方式中一种重要调制方式：最小频移键控（MSK）的基本模型入手,介绍了一种利用Simulink软件实现MSK仿真的方法,并根据最佳状态接收机的原理设计了一种最佳状态接收机模块,通过改变系统的参数,对结果进行了分析,验证了MSK调制解调的性能。     

一种基于MSK调制的直扩/跳频系统设计与实现

基于MSK调制的直扩/跳频混合扩频通信系统不仅具有较高的抗干扰性和保密性,还具备较好的频带利用率和误码性能。结合直扩/跳频混合扩频系统和MSK调制的原理和特点,设计了一种基于MSK调制的直扩/跳频混合扩频通信系统,给出了系统构成、工作原理和相关算法,并搭建硬件平台对其解调性能进行仿真分析,得出系统采用部分匹配滤波法进行解调是比较可行的结论。     

Quadrature Overlapped Raised-Cosine Modulation

A variation of an old but neglected pulse shaping technique, raised-cosine, is investigated. By overlapping raised-cosine pulses in each of two data streams and then by quadrature combining them, a simple QPSK/MSK type modulation results. This quadrature overlapped raised-cosine (QORC) modulation exhibits a hybrid structure of QPSK and MSK modulations. The power spectral density of QORC is shown to take on the form of the product of the power spectral densities of MSK and QPSK. The obvious consequences are that the power spectral density main lobe retains the width of the spectral density main lobe of QPSK, but the sidelobes drop off much faster(1/f^{6}). A simple QORC modulator can be implemented similar to an MSK modulator. Several correlation type receivers are investigated and their performances calculated. Computer simulation results are used to compare end-to-end system performance of QORC and staggered QORC (SQORC) with MSK, QPSK, and staggered QPSK (SQPSK) for both linear and nonlinear satellite channels. The performance of QORC and SQORC compares very favorably with QPSK, SQPSK, and MSK. QORC performs particularly well in the presence of a nonlinear channel. The effect of phase equalization of the channel filter was investigated with outstanding performance improvement. The simulation results show that sidelobe regeneration caused by the channel nonlinearity is much less for SQORC than it is for the other modulation formats considered.     

760 Mbit/s Serial MSK Microwave Modem

Serial modulation and demodulation provide a significant simplification in the hardware realization of high data rate MSK systems. The serial MSK (SMSK) technique results in theoretical performance charateristics identical to conventional MSK. A 750 kbit/s low data rate system and a 760 Mbit/s high data rate system were constructed to evaluate the feasibility of the design concepts. The low data rate system had an overall BER performance degradation of 1.3 dB at a 10^-6BER. The 760 Mbit/s system had a corresponding degradation of 2.0 dB and used direct modulation and demodulation at the 14.7 GHz carrier.     

Optimum Modulation and Channel Filters for Nonlinear Satellite Channels

This is a comparative study of three modulation schemes: QPSK, Offset QPSK(OQPSK), and MSK, in nonlinear satellite channels with adjacent channel interference. Two kinds of typical satellite channel models are used for performance evaluation: one is an INTELSAT type narrow band model and the other is a domestic type wide band model. The transmitter filter and receiver filter are optimized for each combination of modulation scheme, channel model, and an input back-off condition for nonlinear amplifiers. All the combinations considered here have the optimum division of the Nyquist shaping between transmitter filter and receiver filter in common. The filters are a wide band sharp cut-off transmitter filter with flat inband response and a gently rolled-off Nyquist receiver filter with an aperture equalizer (x/sin xor1-(2x)^{2}/cos xequalizer). With these optimized filters, comparisons are made with respect to the bit error rate (BER) performance and phase jitter of the recovered carrier. OQPSK and MSK show superior BER performance to QPSK in the wide band model. However, in the narrow band model, QPSK shows the best BER performance among the three modulation schemes. The phase jitter in the recovered carrier is small for all modulation schemes in the wide band model. But, in the narrow band model, the phase jitter in OQPSK and MSK is four times larger than in QPSK. Generally QPSK is the most preferable modulation scheme in the narrow band model: OQPSK and MSK are most preferable for the wide band model.     

Link-16信号MSK调制模式识别方法

针对Link-16信号采用的最小频移键控(MSK)调制模式,提出了一种基于瞬时特征参量与频谱特征的识别方法。该方法分2个层次进行调制识别,首先利用瞬时特征参量对幅移键控(ASK)、频移键控(FSK)和相移键控(PSK)、MSK信号进行识别,然后再利用频谱特征对MSK、PSK信号进行识别。最后,在特定的数据长度、信号幅度和信噪比的条件下,理论分析与仿真验证该算法易于实现、识别性能较好(90%)。     

Single and Dual-Level Minimum Shift Keying Optical Transmission Systems

We present optical transmission systems employing minimum shift keying modulation formats of single and dual-amplitude level under linear, weakly nonlinear, strongly nonlinear variation of the lightwave carrier within a bit-period depending on whether the phase variation within a symbol period is linear or nonlinear. These formats are externally modulated, incoherently and differentially detected based on the Mach-Zehnder delay interferometric optical balanced receiver. Transmission performance of these optical transmission systems is evaluated in terms of receiver sensitivity, amplification stimulated emission noise loading, dispersion tolerances. These performance characteristics are compared with return-to-zero (RZ) differential phase shift keying (DPSK) and carrier-suppressed RZ on-off keying modulation formats. Accurate bit-error ratios are obtained and confirmed by different statistical techniques: Monte Carlo, single-Gaussian or multiple Gaussian distributions and generalized Pareto distribution statistical methods, especially when the eye diagrams are distorted. Among the three minimum shift keying (MSK) types, the weakly nonlinear optical MSK is found to be the most promising because of its robust transmission performance and more importantly, its reduced-complexity of the electrical driving signals for transmitter in modulating the lightwave carrier as compared to the linear MSK counterpart. Transmission performance of dual-level MSK optical transmission systems depends on the intensity-splitting ratio of the two levels. The performance of three ratios: 0.7/0.3,0.8/0.2, and 0.9/0.1 are demonstrated. The spectral attributes of 80 Gb/s dual-level MSK optical signals for these three ratios are similar to each other and compatible with that of 40 Gb/s optical MSK, but narrower than that of 40 Gb/s optical nonreturn-to-zero DPSK, hence high spectral efficiency of the dual-level MSK.     

Iterative decoding of serially concatenated convolutional codes andMSK

The performance of iterative decoding and demodulation of serially concatenated convolutional codes and minimum shift keying (MSK) is studied. It is shown that by appropriately combining the trellises of MSK and the inner code, a high performance coded modulation system can be achieved. Simulation results also confirms that recursive inner codes are essential for a serially concatenated system     

Blind detection of CPM signals transmitted over frequency-flatfading channels

We propose a novel detection scheme for continuous-phase modulation (CPM) signals transmitted over frequency-flat fading channels. Its most significant feature is that it operates without statistical information on the fading channel, and for this reason it is nicknamed “blind detector.” Its error-rate performance is assessed with minimum shift keying (MSK) and Gaussian MSK (GMSK) schemes and compared with the performance of other decoders     

MSK调制解调与抗噪声性能分析

本文基于仿真工具 Matlab 以及 MSK 相关原理，应用 Matlab 中的 Simulink 函数库， 对 MSK 的调制解调与抗噪声性能进行仿真，并就仿真结果进行分析和比较，得出试验结论。     

Linewidth requirements for optical synchronous detection systemswith nonnegligible loop delay time

The spectral spreads of quadrature-phase-shift-keying (QPSK) modulation and minimum shift keying (MSK) modulation are narrower than those of other kinds of modulation with the same bit rate. Therefore, they are attractive for systems limited by electrical bandwidth and available optical frequency. The synchronous demodulation offers better sensitivity than differential demodulation. However, the propagation delay time of the phase locked loop affects the performance of synchronous detection systems. Therefore, linewidth requirements while considering the loop delay time must be considered in designing these systems. The linewidth requirements for BPSK, QPSK, and MSK homodyne/heterodyne detection systems are obtained by applying the Pade approximation in evaluating the receivers' performance. A change in the power penalty with respect to the change in these values is also obtained     

Space-time coding using MSK

Recent papers have shown that space-time (ST) coding using continuous phase modulation has a number of advantages relative to linear modulation, among which is its constant envelope, which allows transmission with inexpensive and power-efficient Class C amplifiers. The present paper presents a particularly simple variant, ST coding based on minimum shift keying (MSK), an offset format. ST codes with offset modulation give much better performance than quadrature phase shift-keying (QPSK), for the same number of states, and the MSK ST decoding computational load is smaller than that of QPSK by a ratio that improves exponentially with the number of transmitter antennas. The relationship between offset and nonoffset modulation formats is explored and the effect of pulse shape is shown explicitly.     

Feedforward carrier frequency estimation with MSK-type signals

We propose a non-data-aided technique for the estimation of the carrier frequency offset in minimum-shift keying (MSK)-type modulations. The proposed algorithm has a feedforward structure and is suited for burst-mode transmissions. Computer simulations are used to assess its performance and make comparisons with other existing methods in terms of estimation accuracy and minimum operating signal-to-noise ratio (threshold). Numerical results are provided for modulation schemes of practical interest such as MSK and Gaussian MSK     

Error rate performance of noncoherent detection of duobinary coded MSK and TFM in mobile radio communication systems

Two continuous phase constant envelope modulation schemes are considered for use in digital mobile radio communication systems. These two schemes, duobinary coded minimum shift keying (MSK) and tamed frequency modulation (TFM), use partial response signaling to achieve efficient power spectrum. Therefore, they are suitable candidates for the application of digital data transmission via mobile radio where spectrum efficiency is an important consideration. The mobile communication channel is characterized by fast Rayleigh fading and cochannel interference resulting from the reuse of the channels. The error rate performance of duobinary coded MSK and TFM has been studied under these environments with noncoherent detection. A closed form expression for the probability of error of duobinary coded MSK with discriminator detection has been derived and evaluated for different cases of fast and slow fading and cochannel interference. The probability of error of duobinary coded MSK and TFM with differential detection has been calculated by numerical integrations for different cases of slow and fast fading and cochannel interference.     

Conversion and Matched Filter Approximations for Serial Minimum-Shift Keyed Modulation

Serial minimum-shift keyed (MSK) modulation, a technique for generating and detecting MSK using series filtering, is ideally suited for high data rate applications provided the required conversion and matched filters can be closely approximated. Lowpass implementations of these filters as parallel inphase- and quadrature-mixer structures are characterized in this paper in terms of signal-to-noise ratio (SNR) degradation from ideal and envelope deviation. Several hardware implementation techniques utilizing microwave devices or lumped elements are presented. Optimization of parameter values results in realizations whose SNR degradation is less than 0.5 dB at error probabilities of 10^-6.     

基于FPGA的16倍采样MSK调制设计与实现

随着对通信与信号处理算法的研究,合适有效的调制算法能够保证发射信号的质量,进一步提高通信系统的工作性能和指标。介绍了MSK调制原理,设计了一种16倍采样最小频移键控(MSK)调制的方法,并在Xilinx的现场可编程门阵列(FPGA)上实现了该设计,利用Vivado Simulation仿真了调制过程,通过大量测试以及与Matlab计算结果作对比,验证了该设计和实现的正确性,为通信信号的有效传输提供了保证。