中文摘要：

二进制移相键控（BPSK）是水声通信与探测领域常用的调制方式之一,因此BPSK信号也是非合作截获检测研究的重要对象.载频和基带波形是BPSK信号截获处理需要获取的关键信息,在非合作条件下这些参数的自动提取算法需要在无任何先验信息的条件下实现.针对这一难题,本文提出一种利用下变频处理的载频和基带信号波形的方法——基于预设频率搜索的载频估计方法和只利用载频信息的基带信号波形估计方法.基于预设频率搜索的方法利用了不同预设频率时下变频信号的变化特征实现载频的估计,该方法估计精度高,并且在低信噪比下仍具有良好的性能.在获得载频搜索结果后,利用该搜索结果对应的下变频信号的正负变换情况进行波形恢复,即可重现基带信号波形.接收信号初始相位和到达时刻会对下变频处理带来信噪比降低甚至信号趋于零的不利影响,而非合作条件下这两个参数的估计是非常困难的,为保证估计方法的稳定性,提出了下变频信号实部虚部最大幅度选择和基于相位估计的两种处理方法,这两种方法虽然可能损失一定的输出信噪比,但下降范围是有限的.这两种方法降低了参数未知的不利影响,并通过仿真测试和理论分析比较了两种方法的性能.为了验证载频与基带信号波形估计方法的正确性与有效性,利用蒙特卡洛计算机仿真方法进行了测试和验证,结果表明本文提出的载频估计方法性能优于平方法和重心法,对于基带信号波形估计,存在初相位时,基于幅度最大值的方法优于基于相位估计的方法,并且在-5dB时仍具有归一化误差不到5%的估计性能.

英文摘要：

In the area of the underwater acoustics communication and detection,the modulation of binary phase shift keying（BPSK） is one of the commonly used modulation mode.As a result,the non-cooperative intercept processing of BPSK signal is an important research.The carrier frequency and baseband waveform are the critical information of BPSK signal intercept processing.Automatic extraction algorithms of these parameters in the non-cooperation condition are needed to be achieved without any priori information.In the view of this problem,this paper presents a carrier frequency estimation method based on presupposed frequency search and a baseband signal waveform estimation method using the carrier frequency information Both the estimation methods of the signal carrier frequency and the baseband waveform use the down-conversion processing.The carrier frequency estimation method based on presupposed frequency search is achieved by using the changes in characteristics of the down-converted signal with different presupposed frequency.This estimation method is of high accuracy and has a good performance at low signal-to-noise ratio.After the carrier frequency estimation,judging the positive and negative interchange of the down-conversion signal can recover the baseband waveform.For the down-conversion processing,the initial phase and the arrival time of the received signal can bring adverse effects： the signal to noise rate reduces and the signal even tends to zero.And the estimation of the two parameters is very difficult under non-cooperation condition.In order to ensure the stability of the estimation methods,we put forward two approaches： one is to select the largest amplitude of the down-conversion signal both from the real and imaginary parts;another is based on the phase estimation.Although these approaches are possible to lower the output signal-to-noise ratio,the decline range is limited.They reduce the adverse effects of unknown parameters and we compare their performance through theoretical analysis and simul