【作者】 陈勇；

【导师】 黄建国；

【作者基本信息】 西北工业大学 ， 信号与信息处理， 2006， 硕士

【摘要】 在中远程海洋水声信道中，可用带宽窄、多途干扰强、信号起伏衰落严重等因素成为水声信息高速可靠传输的主要障碍，因此如何在远程水声信道中高速率准确地传输数据，成为水声通信技术一个难点。联合频率相位调制(JFPM)同时利用频率信息及相位信息，具有较高的频带利用率和功率效率。本文通过深入研究JFPM调制理论，提出了一种适用于远程水声通信的自差分联合频率相位调制(SD-JFPM)方法，并进行了湖上实验验证。结果表明该方法原理正确，有效可行，具有带宽利用率高，通信距离远，抗多径干扰强的优点，可以满足远程高速水声通信的要求。 论文的主要工作和研究成果包括以下几个方面： 1．在深入研究联合频率相位调制(JFPM)技术基本理论的基础上，提出了一种基于自差分的联合频率相位调制(SD-JFPM)方法。研究结果表明：在衰落信道中，SD-JFPM比JFPM方法具有更强的抗多径性能，因此更适用于远程水声通信。 2．针对SD-JFPM调制，提出了基于频谱结构的相位信息解调方法。该方法利用信号能量进行调制相位估计，因此对同步误差、多普勒效应及多径影响并不敏感。研究结果表明：当信噪比SNR=0dB、同步误差为码元长度的1／10、多普勒因子为0.0022时，该方法仍能正确解调相位信息。 3．针对SD-JFPM调制，提出基于相位补偿的频率解调方法。该方法首先利用调制相位估计值对各个码元进行相位补偿，然后再使用频率估计方法进行频率信息的解调。试验结果表明，在通信距离为25km时，由于使用了相位补偿措施，频率信息解调的误比特率(纠错前)可由原来的4.1％降低到0.65％以下。 4．为了保证SD-JFPM系统有较高的同步精度，提出了一种多段组合线性调频同步头信号(MLFM)。研究结果表明：当多普勒因子δ=0.001时，线性调频信号(LFM)的同步误差为7.9毫秒，而MLFM信号的同步误差仅为3.0毫秒，同步精度提高一倍以上。 5．利用已建立的水声通信系统，对基于自差分联合频率相位调制(SD-JFPM)方法进行了湖上实验验证。实验表明：SD-JFPM水声通信方法原理正确，性能可靠，取得了在通信距离为10km、120bit／s的通信速率，纠错前误比特率为0.9％，以及通信距离为25km、120bit／s的通信速率，纠错前误比特率为1.6％的良好结果，与相同带宽和载波数的单一频率调制的FSK方法相比，可使数据率提高50％，由更多还原

【Abstract】 Narrow available bandwidth, strong multipath disturbance and serious fading in the long-range underwater acoustic channel are main obstacles in the high speed reliable underwater acoustic communication. So this is a difficulty in the world that how to make the communication performance well in such underwater environment. Joint frequency and phase modulation (JFPM) utilize frequency and phase information to realize higher efficiency in the frequency and power. Self-Differential JFDM modulation (SD-JFPM) applying to this channel is presented by deeply investigating in the theory of JFDM, later with the lake experiments. It is resulted the method is available and the principle is feasible since that there are many advantages in the technique of SD-JFPM such as high utilization of bandwidth, far communication distance, better resistance to multipath disturbance, which can meet well in the high speed middle and long range underwater acoustic channel. Research work and achievements that had done in the thesis are summarized as follows.1. A method of Self-Differential Joint Frequency and Phase Modulation is presented for the long-range underwater acoustic communication, based on the study of JFPM technique. It is showed that the method of SD-JFPM resists much more effectively than JFPM the multipath influence in a fading channel. So SD-JFPM is more suitable in application of long-range underwater acoustic communication.2. A phase demodulation method based on the spectrum and energy detection is put forward, which can overcome the influence of the synchronous deviation, Doppler, and multipath effect. Simulation results illustrate that the phase information can be accurately demodulated by this method when the SNR equals to OdB with the Doppler coefficient 0.0022, and the synchronous deviation is 10% of the symbol interval.3. A frequency demodulation method based on phase compensation is proposed for SD-JFPM. In this method, the estimation of modulated phase is utilized for phase compensation, and then the frequency is demodulated by frequency estimation. Experimental results make it clear that the BER of frequency demodulation is decreased from 4.1% to 0.65% by using phase compensation when the communica-更多还原