【正文】
analysis, established the mathematical model of the amplitude modulation circuit, performance is studied by using the MATLAB simulation and analysis, code used in the simulation are given, so as to promote the understanding and application of amplitude modulation circuit skills.Key words: amplitude modulation。 Matlab二、設(shè)計(jì)任務(wù)設(shè)計(jì)任務(wù):實(shí)現(xiàn)振幅調(diào)制信號(hào)實(shí)現(xiàn)Matlab程序的仿真,提供基本的調(diào)制信號(hào)和載波信號(hào),要求輸出調(diào)制信號(hào),載波信號(hào)和已調(diào)信號(hào)的時(shí)域波形以及頻譜圖。振幅調(diào)制,就是由調(diào)制信號(hào)去控制高頻載波的振幅,直至隨調(diào)制信號(hào)做線性變化。根據(jù)調(diào)制的定義,振幅調(diào)制信號(hào)(已調(diào))一般可表示為: Sm(t)=Am(t)cosωct設(shè)調(diào)制信號(hào)m(t)的頻譜為M(ω),則已調(diào)信號(hào)的頻譜為:Sm(ω)=A2Mω+ωcc+M(ωωc)2調(diào)幅電路方案分析標(biāo)準(zhǔn)調(diào)幅波(AM)產(chǎn)生原理調(diào)制信號(hào)是只來來自信源的調(diào)制信號(hào)(基帶信號(hào))這些信號(hào)可以是模擬的,亦可以是數(shù)字的。w12=50*pi。 U2m=2。其次,對(duì)調(diào)制信號(hào)和載波信號(hào)進(jìn)行調(diào)制u1=U11m.*cos((w11).*t)+U12m.*cos((w12).*t)。得到已調(diào)信號(hào),為了方便觀察,對(duì)U1,U2,U3進(jìn)行快速傅立葉變換,并繪制圖像。)。title(39。subplot(3,2,3)。subplot(3,2,4)。zaibopinpu39。plot(t,u3)title(39。Y3=fft(u3)。)。 U11m=。 k=20。 u3=k*u1.*u2。tiaozhixinhao39。 plot(abs(Y1))。axis([0,100,0,100