单信标导航信号检测方法研究

单信标导航方法利用单一信标发射信号，在UUV端接收，通过对信号发射和接收之间的传输时间差的测量换算得到与信标的距离，再加上航行器的运动参量信息对当前位置进行解算。传输时间的测量采用同步方式，其中涉及到UUV与信标基时钟的对准、信号采集窗口的自适应调整、以及ToA的检测问题。ToA的检测方法在提高导航定位精度方面是一个十分关键的因素。为了简化系统，测距采用不带编码的信号。传统的在时域内通过阈值检测ToA的方法在水下无法使用，因为信号会淹没在复杂的噪声环境中。提出了运用短时傅里叶变换（STFT）的方法在时频域内对ToA进行检测，并设计了相应的信号波形。仿真结果表明该办法有效、可行。

Detection of ToA in Single Beacon Navigation

Single beacon navigation is a method which utilizes a single beacon, by transforming the signal transmission time between the beacon and the UUV to the range in addition with the UUV movement information to solve the current position. We use synchronous ways to measure the transmission time which involves the alignment of clocks on the UUV and the beacon, the self-adjust modification of the signal acquisition window and the detection of ToA (time of arrival).The way of detecting ToA is a very crucial factor in improving the accuracy of navigation and position. In order to simplify the system, no-coding signals were adopted to measure the range. Traditional approach which detects ToA through preset threshold in time domain cannot be applied in the complex underwater environment because of the unpredictable noise. To overcome this disadvantage this paper proposed to detect ToA in frequency domain by short time Fourier Transformation and has given the corresponding waveform. The simulation results show the feasibility and validity of the presented approach.