使用於數位磁性記錄系統之循軌校正音調變碼設計

Abstract

這篇論文的主要目的是探討如何使用一種簡易且高速的方法做24/25調變 碼的編碼。由於24/25調變碼有很好的循軌校正音特性，所以目前在一個 國際性的民生用數位錄影機規格會議中已接受其為標準規格之一。對旋轉 式磁頭的磁帶記錄系統而言，要達到自動循軌(auto track following - ATF)功能，調變碼的循軌校正音是極為重要的參考信號。事實上，依 照24/25碼的規格需求，我們可以使用一種較直接的演算法做編碼，而這 篇論文也是由這個方法開使討論。但由於24/25碼所應用的領域是民生電 子產品，基本上我們期望編碼器做成IC時，邏輯閘數不要超過6000，編碼 速度能到達每秒45Mbits/sec。加入這樣的考量，直接演算法會遇到兩個 問題：第一是浮點及乘法運算；第二是複雜的判別程序。這篇論文將逐步 討論如何達到簡易且高速編碼的方法，每個步驟都會配合軟體( C++ 及 Matlab )的模擬結果作分析。最後提出一個符合我們期望的編碼硬體架構 及時序。 The target of this thesis is to design a simple and fast methodology for encoding a 24/25 modulation code. The 24/25 code has been adopted by an international standard committee of consumer used digital VCR, because of its well defined trait, pilot tracking tone. This trait is very important to auto track following (ATF) of rotary head magnetic tape recording. In fact, we can find a very straight forward solution to generate the code within the criteria of 24/25 code . This thesis will start from discussion of this solution. Because the 24/25 code will be used in consumer electronic products. Generally speaking, the reasonable IC gate count of the encoding core is better to be less than 6000 and the coding speed is up to 45Mbits/sec. Under these considerations, the straight forward method will impact on two problems. The first is floating point and mutiply calculation and the other is sophisticated strategy decision. Every step leading to the simple and fast methodology is given with software (C++ and Matlab) simulation. also a hardware architecture will be proposed in this article.