Re: [問題] 為什麼訊號要升到高頻再傳呢?
※ 引述《beareyes (熊眼)》之銘言：
: 把訊號升到高頻的好處
: 以前我只知道 避免低頻雜訊，接收天線較短
: 但後來聽到有人說"可傳送的bit rate較高"
: 請問這是為什麼呢?
: 另外
: 升到高頻有什麼缺點嗎?
: 剛進入通訊這行不久
: 有很多知識不懂
: 謝謝大家幫忙
advantages using higher frequency bands
．larger instantaneous bandwidth for greater transfer of information
．higher resolution for radar , bigger doppler shift for CW radar , and more
detailed imaging and sensing
．reduced dimensions for antennas and other components
．less interference from nearby applications
．fast speed for digital system signal processing and data transmission
．less crowded spectrum
．difficulty in jamming (military application)
disadvantages using higher frequency bands
．more expensive components
．higher atomspheric losses
．reliance on GaAs instead of Si technology
．higher component losses and lower output power from active devices
．less accurate design tools and less mature technologies
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09/22 00:11, , 1F
09/22 00:11, 1F
數位通訊中用Gigabit/sec來描述數位資料傳遞的速度，這個會對應到它需要佔用的頻寬
，愈寬的頻寬，可以傳送的數位資料的數度愈快。頻率比較高時，一樣是相對頻寬5%，60
GHz*5%和2GHz*5%，對應到的絕對頻寬當然是用60GHz比較大，絕對頻寬愈寬，提供上述的
數位通訊的頻寬就愈大，可以傳輸的速度就愈快。
※ 編輯: big1p 來自: 1.160.78.8 (09/23 23:55)
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