碼相位擷取裝置及方法METHOD AND DEVICE FOR ACQUIRING A CODE PHASE SHIFT BETWEEN AN INPUT SEQUENCE AND A REFERENCE SEQUENCE

專利類型

發明

專利國別 (專利申請國家)

美國

專利申請案號

13/605,650

專利證號

US 8,902,952 B2

專利獲證名稱

碼相位擷取裝置及方法METHOD AND DEVICE FOR ACQUIRING A CODE PHASE SHIFT BETWEEN AN INPUT SEQUENCE AND A REFERENCE SEQUENCE

專利所屬機關 (申請機關)

財團法人國家實驗研究院

獲證日期

2014/12/02

技術說明

快速傅立葉轉換(Fast Fourier Transform, FFT)運用卷積定理(convolution theorem)時被廣泛地使用在偽隨機碼對準(PN sequence matching)的各項應用上，如展頻通訊與全球衛星定位(GPS/GNSS)接收器，以確認發送器的身份與搜尋正確的碼相位(code phase). 長度N的FFT計算量需要 Nlog2N 階的複數乘法和Nlog2N 階的複數加法。由於現代漸趨複雜的應用和需求，需處理的長度N漸趨變大以致於連FFT也不易實現。 在本發明中，我們提出一個新的方法比FFT換使用更少許多的計算量! 此法稱為相位對應擷取法 (Phase Coherence Acquisition, PCA)。與FFT相比，PCA僅需要 N 階的複數加法且不需要任何的乘法。 Fast Fourier Transform (FFT) is widely adopted as a tool to achieve pseudo-noise (PN) sequence matching in many applications such as spread spectrum communications and GPS/GNSS receivers, to identify the transmitter ID and search the correct code phase using convolution theorem. The computation of FFT of length N costs complex multiplications of order Nlog2N and complex additions of order Nlog2N. Due to the the increasing complexity of modern algorithm and diverse need of applications, the applied sequence N may become very large such that the implementation of FFT becomes infeasible. In this invention, we propose an approach, called Phase Coherence Acquisition (PCA) method, using much less computation than FFT to achieve PN sequences matching. The computation of PCA only costs complex additions of order N and requires none of multiplications.

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