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Global positioning system signal acquisition and tracking using field programmable gate arrays.

机译：全球定位系统的信号采集和跟踪使用现场可编程门阵列。

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GPS receivers spend much of their time on acquisition and tracking. Slow acquisition is due to the large computation time of the correlation function. The correlation function searches for the code phase between the GPS receiver signal arrival time and the GPS satellite's signal transmission time. The computation of the correlation function in frequency domain is speed up N/logN times compared with the time domain implementation.; The long computation time for the correlation function is due to the computation of the FFT functions. One possible solution to speed up the calculations of the correlation function is by replacing the FFTs with simpler transforms. Two transforms were studied in this work. A real transform called the Fermat number transform (FNT) was presented. The FNT-based convolution algorithm was shown. However, the FNT-based convolution has a sequence length restriction that makes it not applicable to the GPS case. A binary transform called the Walsh Hadamard transform (WHT) was also investigated. The WHT-based correlation algorithm was presented and verified. This method shows a significant reduction in the computing time of the correlation function by approximately 20 times compared to the FFT method. The Walsh Hadamard method is not directly applicable to the GPS C/A code, so was not used for GPS signal acquisition.; This dissertation also illustrates a realistic solution to the slow acquisition of the GPS receivers. It uses the FPGA technology along with an averaging method to speed up the calculations of the FFT-based correlation function and to reduce the hardware requirements. The developed method approximated the correlation function by using a modified version of the CIA code. This approximation was accurate enough to use in the acquisition process while maintaining an acceptable level of signal power. This algorithm was used to guide three serial correlators to zoomin around the correlation peak and provide refined versions of the acquisition estimates. This unique algorithm was implemented and then successfully acquired a GPS signal in less than 1-ms.
机译：GPS接收机将大量时间用于采集和跟踪。采集速度慢是由于相关函数的计算时间较长。相关函数在GPS接收器信号到达时间和GPS卫星的信号传输时间之间搜索代码相位。与时域实现相比，频域中相关函数的计算速度提高了N / logN倍。相关函数的计算时间长是由于FFT函数的计算所致。加快相关函数计算的一种可能解决方案是用更简单的变换替换FFT。在这项工作中研究了两种转换。提出了称为费马数变换（FNT）的真实变换。显示了基于FNT的卷积算法。但是，基于FNT的卷积具有序列长度限制，这使其不适用于GPS情况。还研究了称为Walsh Hadamard变换（WHT）的二进制变换。提出并验证了基于WHT的相关算法。与FFT方法相比，该方法显示出相关函数的计算时间显着减少了大约20倍。 Walsh Hadamard方法不适用于GPS C / A代码，因此未用于GPS信号采集。本文还为GPS接收机的慢速采集提供了一种切实可行的解决方案。它使用FPGA技术以及平均方法来加快基于FFT的相关函数的计算并降低硬件要求。所开发的方法通过使用CIA代码的修改版本来近似相关函数。这种近似值足够精确，可以在采集过程中使用，同时保持可接受的信号功率水平。该算法用于指导三个串行相关器在相关峰附近放大并提供采集估计的精炼版本。实施了这种独特的算法，然后在不到1毫秒的时间内成功获取了GPS信号。

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