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Rapid Acquisition for Direct Sequence Spread-Spectrum Signals
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摘要: 提出一种新的基于频域并行搜捕法的改进型快捕电路结构.该结构利用设计复用技术实现FFT单元和IFFT单元的复用;通过软件计算本地伪码FFT,并将其结果存储在ROM中,使硬件规模大幅减少;采用并行设计提高系统的运算速度;采用块浮点算法提高动态范围和运算精度.整个快捕电路由一块FPGA XC 2V 3000-5实现,工作时钟为29 ns,精度为1/4码片情况下,伪码捕获仅需4.145 m s.仿真和测试结果验证了设计的正确性.Abstract: A new improved architecture to realize rapid acquisition for direct sequence spread-spectrum signals was presented.To reduce hardware resources,this architecture utilized duplicate design to realize FFT and IFFT in the same unit and calculated the FFT of local code by software and stored it in ROM;this design applied parallel pipeline structure to improve the processing speed;block floating-point arithmetic was used to enhance the dynamic range and computation accuracy.The whole design was implemented with only one chip of XC2V3000-5 FPGA.When working clock was 29 ns and acquisition precision was 1/4 code,the acquisition time would be within 4.145 ms.The validity of design is verified by simulation and measurement results.
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