PAGEPAGE48.9ASK調(diào)制VHDL程序及仿真1.ASK調(diào)制VHDL程序--文件名：PL_ASK--功能：基于VHDL硬件描述語言，對(duì)基帶信號(hào)進(jìn)行ASK振幅調(diào)制--最后修改日期：2004.3.16libraryieee;useieee.std_logic_arith.all;useieee.std_logic_1164.all;useieee.std_logic_unsigned.all;entityPL_ASKisport(clk:instd_logic;--系統(tǒng)時(shí)鐘start:instd_logic;--開始調(diào)制信號(hào)x:instd_logic;--基帶信號(hào)y:outstd_logic);--調(diào)制信號(hào)endPL_ASK;architecturebehavofPL_ASKissignalq:integerrange0to3;--分頻計(jì)數(shù)器signalf:std_logic;--載波信號(hào)beginprocess(clk)beginifclk'eventandclk='1'thenifstart='0'thenq<=0;elsifq<=1thenf<='1';q<=q+1;--改變q后面數(shù)字的大小，就可以改變載波信號(hào)的占空比elsifq=3thenf<='0';q<=0;--改變q后面數(shù)字的大小，就可以改變載波信號(hào)的頻率elsef<='0';q<=q+1;endif;endif;endprocess;y<=xandf;--對(duì)基帶碼進(jìn)行調(diào)制endbehav;2.ASK調(diào)制VHDL程序仿真圖及注釋ASK調(diào)制VHDL程序仿真圖及注釋如圖8.9.7所示。（a）ASK調(diào)制仿真全圖注：a.基帶碼長等于載波f的6個(gè)周期。b.輸出的調(diào)制信號(hào)y滯后于輸入基帶信號(hào)x一個(gè)clk時(shí)間。（b）ASK調(diào)制仿真局部放大圖圖8.9.7ASK調(diào)制VHDL程序仿真圖及注釋8.9.6ASK解調(diào)VHDL程序及仿真1.ASK解調(diào)VHDL程序--文件名：PL_ASK2--功能：基于VHDL硬件描述語言，對(duì)ASK調(diào)制信號(hào)進(jìn)行解調(diào)--最后修改日期：2004.2.12libraryieee;useieee.std_logic_arith.all;useieee.std_logic_1164.all;useieee.std_logic_unsigned.all;entityPL_ASK2isport(clk:instd_logic;--系統(tǒng)時(shí)鐘start:instd_logic;--同步信號(hào)x:instd_logic;--調(diào)制信號(hào)y:outstd_logic);--基帶信號(hào)endPL_ASK2;architecturebehavofPL_ASK2issignalq:integerrange0to11;--計(jì)數(shù)器signalxx:std_logic;--寄存x信號(hào)signalm:integerrange0to5;--計(jì)xx的脈沖數(shù)beginprocess(clk)--對(duì)系統(tǒng)時(shí)鐘進(jìn)行q分頻，beginifclk'eventandclk='1'thenxx<=x;--clk上升沿時(shí)，把x信號(hào)賦給中間信號(hào)xxifstart='0'thenq<=0;--if語句完成q的循環(huán)計(jì)數(shù)elsifq=11thenq<=0;elseq<=q+1;endif;endif;endprocess;process(xx,q)--此進(jìn)程完成ASK解調(diào)beginifq=11thenm<=0;--m計(jì)數(shù)器清零elsifq=10thenifm<=3theny<='0';--if語句通過對(duì)m大小，來判決y輸出的電平elsey<='1';endif;elsifxx'eventandxx='1'thenm<=m+1;--計(jì)xx信號(hào)的脈沖個(gè)數(shù)endif;endprocess;endbehav;2.ASK程序解調(diào)仿真圖及注釋ASK程序解調(diào)仿真圖及注釋如圖8.9.10所示。（a）ASK解調(diào)仿真全圖注：a.在q=11時(shí)，m清零。b.在q=10時(shí)，根據(jù)m的大