點解有D Lift 可以容許傾電話, 有D唔得呢??

2007-06-11 11:42 pm
點解有D Lift 可以容許傾電話, 有D唔得呢??

回答 (4)

2007-06-11 11:47 pm
✔ 最佳答案
Antenna 天線
透過無線電波傳送和接收電磁訊號的裝置。

Attenuation 衰減
訊號光波、電子或無線電訊號強度減弱的情況,通常與訊號傳送的距離有關。例如,透過光纖傳送之訊號,必須每隔三十哩加強一次。無線電訊號會受到不同因素影響而衰減,如大氣環境、太陽黑子、天線設計或擺放位置,及視線範圍之障礙物。通常以分貝 (Db) 比率顯示。

Base Station基站
固定無線電傳送器/接收器,在特定範圍內(即一個發射基組)轉送訊號往返流動終端裝置或手機。基站裝置所需設備,以便流動電話打出並完成通話,設備包括 FM 固定無線電傳送器/接收器,在特定範圍內(即一個發射基組)轉送訊號往返流動終端裝置或手機。基站裝置所需設備,以便流動電話打出並完成通話,設備包括FM無線電傳送器和接收器、天線及電腦。基站的運作需配合手機和流動電話中心,才能完成通話。無線電傳送器和接收器、天線及電腦。基站的運作需配合手機和流動電話中心,才能完成通話。

Coverage網絡覆蓋
流動電話網絡或系統所覆蓋的範圍。

Line of Sight視線範圍
天線之間的無遮擋路徑,對甚高頻 WLL 的運作十分重要。
2007-06-12 12:04 am
They almost answer half of your question.

Inside a metallic body (or inside a metal). There are no electric field. This is called as Faraday Cage.

Since there is no electric field, so no EM wave cannot propagate in or out, unless there is an antenna.

In many heavy industial, eg. making aircraft, people would use a large metallic net to shield off external electric field. If you have heard the EMP, electromagnetic pulses, then you can shield your electric instrucment away from EMP by put it in a metallic box. (Faraday Cage)
2007-06-11 11:52 pm
The reception of mobile phone (GSM) signal is very poor inside a life unless that building has installed an antenna to amplified the signal.
參考: Personal opinion
2007-06-11 11:48 pm
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因為唔係所有 l i f t 都裝有電訊公司ge發射器
所以有D l i f i t 可講到電話
有D唔得
ed情況通常可自己發現到
好似我住個到
電訊形科就冇係 l i f i t 到裝發射器
so我次次入l i f i t都講唔到電話

★☆★☆★☆★☆★☆★☆★☆★☆★☆★☆★☆★☆★☆★☆★☆★☆★☆★☆★☆★


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