批踢踢實業坊 Examination 板: [考題] 通訊系統歷屆考題數題－2016徵求年菜推薦網路訂購最紅的商家.年菜訂購?台北年菜外送餐廳推薦(年菜)?年菜.今年不想做年菜推薦,網路宅配哪一家好?

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批踢踢實業坊 Examination 板

Aug 5th 2013, 21:43, by tsamarfi

作者tsamarfi (一擊入魂)

看板Examination

標題[考題] 通訊系統歷屆考題數題

時間Mon Aug 5 21:43:44 2013

[考題] 國考歷屆考題與考題觀念討論(書裡看到的選這個)請附上想法、出處以下解答請幫我檢驗一下是否正確，謝謝。 101調特：以下連結為考選部考畢試題 http://wwwc.moex.gov.tw/ExamQuesFiles/Question/101/101140_40950.pdf 第三題： (一) X(f)=rect(f/2) Y(f)=rect(f/2)*[-jsgn(f)] =jrect(f+0.5)-jrect(f-0.5) y(t)=jsinc(t)exp(-jπt)-jsinc(t)exp(jπt) =jsinc(t)[exp(-jπt)-exp(jπt)] =jsinc(t)[-2jsin(πt)] =2sin(πt)sinc(t) =[1-cos(2πt)]/(πt) ============================================================================= 97調特：以下連結為考選部考畢試題 http://wwwc.moex.gov.tw/ExamQuesFiles/Question/097/026306300.pdf 第一題： (二) 由於打出係數太雜亂，因此只敘述我解題的想法。題目給的是一個週期性的方波，高值為1，低值為-1，週期1/3000。我把x(t)表示為振幅為2(即高值為2，低值為0)的週期性方波，然後整體減一(即下降1，成為高值為1，低值為-1)。化為頻域則為「無限個sinc函數相加-δ(f)」，接下來當然是乘上|H(f)|∠H(f)，但是「無限個sinc函數相加」我還真不知道怎麼處理...@@" 請問是有其他的作法來解嗎？謝謝。 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 1.174.225.234

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