數(shù)字信號外文翻譯--基于fpga的cordic算法綜述-免費閱讀
【正文】 然而，現(xiàn)在絕大多數(shù)的硬件 DSP 設(shè)計很少被工程師用到或者被沒有學(xué)過硬件的工程師有效地實現(xiàn) DSP 算法。第一種更蒹容旋轉(zhuǎn)角的連續(xù)性，而第二種是當接線受到限制時更為方便，它往往用于 FPGA 中。y d x?? 39。如果角度累加器被初始化為零，它在迭代完后包含中間角。 在旋轉(zhuǎn)模 式下，角度累加器被初始化為所需要的旋轉(zhuǎn)角度。這個角度系統(tǒng)和任何其它系統(tǒng)之間轉(zhuǎn)換都可以通過查找來完成。現(xiàn)在 迭代旋轉(zhuǎn)可以表述為： 1 [ 2 ]ii i i i ix k x y d ?? ? ? ? ? 1 ii i i i iy y x ?? ? ? ? 其中： 21/ 1 2 iik ??? 1id?? 去掉從迭代方程不斷產(chǎn)生的一個移位加法算就得到旋轉(zhuǎn)向量。該算法是從一般的（吉文斯）旋轉(zhuǎn)變換得到的： 39。在這些硬件高效的算法中是通過一種迭代的方法解決三角函數(shù)和其他抽象函數(shù)的， 這樣就只使用了移位器和加法器來實現(xiàn)。在這些算法中，是由一系列移位加法算集成的被稱為 ORDIC 算法，它用來計算一系列函數(shù)如三角函數(shù)，雙曲函數(shù)，線性函數(shù)和對數(shù)函數(shù)。x d y?? ? 39。A survey of CORDIC algorithms for FPGA based puters 1. ABSTRACT The current trend back toward hardware intensive signal processing has uncovered a relative lack of understanding of hardware signal processing architectures. Many hardware efficient algorithms exist, but these are generally not well known due to the dominance of software systems over the past quarter century. Among these algorithms is a set of shiftadd algorithms collectively known as CORDIC for puting a wide range of functions including certain trigonometric, hyperbolic, linear and logarithmic functions. While there are numerous articles covering various aspects of CORDIC algorithms, very few survey more than one or two, and even fewer concentrate on implementation in FPGAs. This paper attempts to survey monly used functions that may be acplished using a CORDIC architecture, explain how the algorithms work, and explore implementation specific to FPGAs. 2. INTRODUCTION The digital signal processing landscape has long been dominated by microprocessors with enhancements such as single cycle multiplyaccumulate instructions and special addressing modes. While these processors are low cost and offer extreme flexiblility, they are often not fast enough for truly demanding DSP tasks. The advent of reconfigurable logic puters permits the higher speeds of dedicated hardware solutions at costs that are petitive with the traditional software approach. Unfortunately, algorithms optimized for these microprocessor based systems do not usually map well into hardware. While hardware efficient solutions often exist, the dominance of the software systems has kept those solutions out of the spotlight. Among these hardwareefficient algorithms is a class of iterative solutions for trigonometric and other transcendental functions that use only shifts and adds to perform. The trigonometric functions are based on vector rotations, other functions such as square root are implemented using an incremental expression of the desired function. The trigonometric algorithm is called CORDIC, an ac
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