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1()()21imTTTx tx t dtT1()()()()21imTTTx t x tx t x tdtT1()()()2limTXXTTE X tx tx t dtT)()()(21)()()(limXTTTXRdttxtxTRtXtXE,(,)()()X YXYfx yfx fy,0Cov X Y(),()()()0 x ty tx t y tdt,0X YdttxdttxETTT22)()(lim221()()2Ex tdtX jdTTTdttxTP2)(21lim22111()()222limlimTTTTTTPx t dtXdTT222111()()22211()22limlimlimTTTTTTTTE PEx t dtEXdTTEXdT2)(21)(limTTXXETGdtetxXtjTT)()(2121()*1212()*12121()()()21()()2limlimTTjttXTTTTTTTjttTTTGEx t x t edt dtTE X t Xtedt dtT )()()()(211221ttRttRtXtXEXXTT21tt TTTTttjXTXdtdtettRTG21)(1212)(21)(limTTjXTXdeRTG22)()21()(limT(1)2TTTjXXdeRG22)()(TTjXXdeGR22)(21)()sin()(0ttX0其他 020 21)(f),(21ttRX12(,)XGt t000()()1cos()()22jXXjGReded 1(,)()()cos()2XRt tE X t X t000022()1111112j tXj tj tj tj tGeedededeejjjjjj eRX)(1()fdt1()()()ff tH f tdt11()()gHg tdt1()()*f tf tt1()gdt()f t1sgn()jt (90)0()sgn (90)0jH jjj sgn()x1 0sgn()1 0 xxx th Ftf Ftf sgnj 1f tf th tf tt j (90)0jsgnj (90)0 FFFF 1()()Hf tf t()()H f tf t 22()()ft dtft dt()f t()()0f t f t dt()f t()()()z tf tjf t()()ef tR z t*1()()()2f tz tz t()()f tF()()z tZ2()0()0 0FZ0011()2()()2j tj tz tFedFed0 0()()2()()2()0F z tF z tFuF1()z t2()z t12()()0z tz t12()()0z tz t()cosf tt()f t)()()()(00 FtfsgnFjF)()()(00jFttfsin)(000cossinjtZ tf tj f ttjte解：仍利用频域函数来求解。由频域搬移性可知：00()()cos,ff tm ttf t且，其中求的低通信号，为截至频率为若fMtm)()()()(21)()(00MMFtf ffffjMjMjFF0000002/)(2/)(sgn于是 这不是一个常用的函数，所以无法通过查表而只能来做它的付氏反变换。deFtftj2/1deMjdeMjtjtjffff0000002221带入上式令00,vu 2/12/12)()(00dvevMdueuMjtftvjtujffff则ttm0sin)()(200eetmjtjtj tft0cos t0sin t0sin t0cos t0je t0jje ttm0je ttm0jej tf()()()()()()()Y tX th tXh tdh u X tu du()()()()()()()(0)XXXE Y tEh u X tu duh u E X tu duh u m dumh u dum H1212121212(,)()()()()()()()()()()()()()()()()()()YXYR t tE Y t Y tEh u X tu duh v X tv dvEh u h v X tu X tv dudvE X tu X tv h u h v dudvRuv h u h v dudvR 1212121221(,)()()()()()()()()()()()()()()()XYXXXXYRt tE X t Y tE X tX tu h u duE X t X tu h u duRtut h u duRu h u duRuhR()()()()()()XYXYXXGF RF RF hGH()()()()()()()()jYYjXjXGRedRuv h u h v dudv edh uh vRuv ed dudv 2*()()()()()()()()()j uj vjYXXXGh u eh v eRed dvduHHGHGuvuv()X t12121221(,)()()()()()()()()()()()()XXXXXXRt tE X t X tE X t X tu h u duRtut h u duRu h u duRhR()()()()()()()XXXXXGF Rh tF RF h tGH0023(),21.38 10Joules/KelvinnBeBNGNk Tk 0()()2nNR 02121()()2nNR tttt0()()TXn tt dt()t2200()2TXNt dt110()()TXn tt dt210()()TXn tt dt1()t2()t012120()()()2TNE X Xtt dt1()t2()t120()()0Ttt dt1X2X0H,()2,20,HnHHNGf222001()()21(2)2sin2222HHHHHjnnfjfnfjfjfHHHRGedGf edfNfeeN fjf c()()cos()cX tttt()t()t()()cos()cos()sin()sinccX ttttttt()()cos()cXttt()()sin()sXttt()cXt()sXt()t()t()cXt()sXt
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