提出了一種基于FPGA的驗光儀的數(shù)據(jù)實時無損壓縮系統(tǒng)，采用LZW算法。首先通過對比分析常用數(shù)據(jù)無損壓縮算法的特點得出LZW算法在實時性、實現(xiàn)復雜度、所需的存儲容量、算法的壓縮效果和適用的場合方面都有不錯的特點，因此以它作為硬件實現(xiàn)的算法。此數(shù)據(jù)實時無損壓縮系統(tǒng)由數(shù)據(jù)實時無損壓縮硬件電路、測試軟件、解壓軟件與讀數(shù)軟件組成，其中數(shù)據(jù)實時無損壓縮硬件電路由數(shù)據(jù)采集、數(shù)據(jù)壓縮、控制單元、數(shù)據(jù)存儲、電源管理等幾部分組成，核心器件是FPGA，利用FPGA芯片內部的RAM資源構成輸入數(shù)據(jù)的緩存器以及LZW算法所需的2個字典存儲器，并結合有利于硬件實現(xiàn)的字典管理策略完成了實時無損壓縮，同時FPGA還負責對模數(shù)轉換器、閃存的控制等功能。結果表明該方案所占邏輯資源較少、可移植性強、功能擴展容易，數(shù)據(jù)的存儲和傳輸效率提高了20%，成本降低了13%。

　　Abstract:

　　The real-time data nondestructive compression system of optometry instrument based on FPGA was presented， it adopted LZW algorithm. First， through comparison and analyzing the characteristic of common data， it obtained that the LZW algorithm had good characteristics in real time and realization suitable occasion and the compressed effect of complex degree， the memory capacity of requirement， therefore， it was used as the algorithm. This data nondestructive compressed system of real time was composed by hardware circuit and test software and decompression software and reading software， the data nondestructive compressed hardware circuit of real time was composed by data collection， data compression， control unit data storage and the management of power source， key device is FPGA， using the built-in RAM resource of FPGA chip， forms the 2 slow dictionary memories of data-in needed for storing ware as well as LZW algorithm， and the dictionary management strategy combined is helpful for hardware to realize the real-time nondestructive compression， at the same time， FPGA still takes the responsibility for modulus converter， control t store of dodge. The results show that the system takes little logic resource， has strong transplantability， easy function development， data stock and transmit efficiency have raised 20%， cost has reduced 13%.