衛星電視接收機放大器的作用 衛星電視接收機放大器使用注意事項
衛星電視接收機放大器的作用
當我們接收遠距離的電視節目時,電視信號一般都比較微弱,這時需要使用方向性強、增益高的多單元電視衛星電視接收機,還(huan)需將(jiang)衛星電(dian)視(shi)接(jie)(jie)(jie)收(shou)機(ji)(ji)架(jia)設在盡(jin)可能(neng)高的地方(fang)。如(ru)感到接(jie)(jie)(jie)收(shou)情況還(huan)不夠理想(xiang),則需在衛星電(dian)視(shi)接(jie)(jie)(jie)收(shou)機(ji)(ji)與電(dian)視(shi)機(ji)(ji)之間再加裝衛星電(dian)視(shi)接(jie)(jie)(jie)收(shou)機(ji)(ji)放(fang)大(da)器,以提(ti)高接(jie)(jie)(jie)收(shou)靈(ling)敏度,使電(dian)視(shi)機(ji)(ji)的圖像(xiang)穩定,伴音(yin)良好。
使用(yong)衛星電(dian)視(shi)接收(shou)機放(fang)(fang)(fang)大(da)(da)器后,就好比(bi)給電(dian)視(shi)機加上了"望(wang)遠(yuan)鏡",它能(neng)夠對衛星電(dian)視(shi)接收(shou)機接收(shou)到的微弱(ruo)的電(dian)視(shi)信號(hao)進入放(fang)(fang)(fang)大(da)(da)。通(tong)常衛星電(dian)視(shi)接收(shou)機放(fang)(fang)(fang)大(da)(da)器下能(neng)把電(dian)視(shi)信號(hao)放(fang)(fang)(fang)大(da)(da)到十幾倍甚至(zhi)更(geng)大(da)(da)些。
衛(wei)星電視(shi)接(jie)收(shou)機(ji)(ji)放大器實際上是一種超(chao)大高(gao)頻(pin)帶放大器,各種型號的衛(wei)星電視(shi)接(jie)收(shou)機(ji)(ji)放大器的接(jie)收(shou)頻(pin)道、頻(pin)率范圍以及整機(ji)(ji)增益都(dou)有所(suo)不同(tong)。
衛星電視接收機放大器使用注意事項
(1)注意安(an)裝位置衛(wei)星(xing)(xing)電(dian)(dian)視(shi)(shi)接(jie)(jie)收(shou)(shou)(shou)機放大(da)(da)器通常由放大(da)(da)部(bu)(bu)(bu)分(fen)(fen)和電(dian)(dian)源供(gong)給(gei)兩部(bu)(bu)(bu)分(fen)(fen)組(zu)成。在(zai)(zai)衛(wei)星(xing)(xing)電(dian)(dian)視(shi)(shi)接(jie)(jie)收(shou)(shou)(shou)機饋(kui)線(xian)較(jiao)短(一般指使(shi)用(yong)室內(nei)衛(wei)星(xing)(xing)電(dian)(dian)視(shi)(shi)接(jie)(jie)收(shou)(shou)(shou)機)的情況下,衛(wei)星(xing)(xing)電(dian)(dian)視(shi)(shi)接(jie)(jie)收(shou)(shou)(shou)機放大(da)(da)器可(ke)放在(zai)(zai)電(dian)(dian)視(shi)(shi)機旁(pang);當(dang)衛(wei)星(xing)(xing)電(dian)(dian)視(shi)(shi)接(jie)(jie)收(shou)(shou)(shou)機架(jia)設得較(jiao)高、饋(kui)線(xian)較(jiao)長時,則兩部(bu)(bu)(bu)分(fen)(fen)應分(fen)(fen)開安(an)置,放大(da)(da)部(bu)(bu)(bu)分(fen)(fen)經防水盒密封(feng)后(hou),最好能安(an)裝在(zai)(zai)離(li)衛(wei)星(xing)(xing)電(dian)(dian)視(shi)(shi)接(jie)(jie)收(shou)(shou)(shou)機振(zhen)子1~1.5m的支(zhi)撐(cheng)桿(gan)端部(bu)(bu)(bu),電(dian)(dian)源供(gong)給(gei)部(bu)(bu)(bu)分(fen)(fen)可(ke)放在(zai)(zai)電(dian)(dian)視(shi)(shi)機附近,這樣能改善電(dian)(dian)視(shi)(shi)信(xin)號的信(xin)噪比。
(2)頻(pin)(pin)道(dao)(dao)必須相符(fu)(fu)衛(wei)星電視(shi)接收機(ji)放大器(qi)一般(ban)分甚高頻(pin)(pin)和特高頻(pin)(pin)兩大類。甚高頻(pin)(pin)型的(de)(de)能放大1~12頻(pin)(pin)道(dao)(dao)的(de)(de)電視(shi)信號(hao),特高頻(pin)(pin)型的(de)(de)能放大13~68頻(pin)(pin)道(dao)(dao)的(de)(de)電視(shi)信號(hao)。使用(yong)時,衛(wei)星電視(shi)接收機(ji)放大器(qi)應該與(yu)所(suo)要接收的(de)(de)電視(shi)頻(pin)(pin)道(dao)(dao)相符(fu)(fu)合(he)。
(3)注意阻(zu)抗(kang)匹配衛(wei)(wei)星(xing)(xing)(xing)電(dian)(dian)(dian)(dian)(dian)視(shi)接(jie)(jie)收(shou)機(ji)(ji)放(fang)(fang)(fang)大(da)器與衛(wei)(wei)星(xing)(xing)(xing)電(dian)(dian)(dian)(dian)(dian)視(shi)接(jie)(jie)收(shou)機(ji)(ji)輸(shu)(shu)(shu)出(chu)端的(de)輸(shu)(shu)(shu)出(chu)阻(zu)抗(kang)以及電(dian)(dian)(dian)(dian)(dian)視(shi)機(ji)(ji)的(de)輸(shu)(shu)(shu)入阻(zu)抗(kang)都應該相匹配。饋(kui)線不要(yao)太長,也(ye)就是說,衛(wei)(wei)星(xing)(xing)(xing)電(dian)(dian)(dian)(dian)(dian)視(shi)接(jie)(jie)收(shou)機(ji)(ji)不能(neng)(neng)架得(de)太高(gao)、太遠(yuan)。否則,雖然給電(dian)(dian)(dian)(dian)(dian)視(shi)機(ji)(ji)加了衛(wei)(wei)星(xing)(xing)(xing)電(dian)(dian)(dian)(dian)(dian)視(shi)接(jie)(jie)收(shou)機(ji)(ji)放(fang)(fang)(fang)大(da)器,但增大(da)后的(de)信號(hao)還會在輸(shu)(shu)(shu)送給電(dian)(dian)(dian)(dian)(dian)視(shi)機(ji)(ji)的(de)過程中被嚴重衰減(jian),致使接(jie)(jie)收(shou)效果(guo)提高(gao)甚(shen)微(wei)。另(ling)外,衛(wei)(wei)星(xing)(xing)(xing)電(dian)(dian)(dian)(dian)(dian)視(shi)接(jie)(jie)收(shou)機(ji)(ji)放(fang)(fang)(fang)大(da)器的(de)輸(shu)(shu)(shu)入與輸(shu)(shu)(shu)出(chu)饋(kui)線不能(neng)(neng)重疊,也(ye)不能(neng)(neng)靠得(de)太近,以免產(chan)生反(fan)饋(kui)或干(gan)擾。
(4)必須選擇增益(yi)(yi)各種型(xing)號的(de)(de)衛星電視(shi)接收(shou)機(ji)放(fang)大器的(de)(de)增益(yi)(yi)有(you)(you)所不同(tong),一(yi)般有(you)(you)高低(di)之分(fen)。高增益(yi)(yi)衛星電視(shi)接收(shou)機(ji)放(fang)大器通常增益(yi)(yi)為30~60dB,與(yu)多頻道八木衛星電視(shi)接收(shou)機(ji)配合,能(neng)接收(shou)幾(ji)百公里外的(de)(de)電視(shi)節目(mu)。低(di)增益(yi)(yi)衛星電視(shi)接收(shou)機(ji)放(fang)大器有(you)(you)20~4OdB的(de)(de)增益(yi)(yi),能(neng)接收(shou)幾(ji)十公里外的(de)(de)節目(mu)。選用時要(yao)作適當選擇,但(dan)并非(fei)增益(yi)(yi)越高越好。
(5)檢(jian)查安(an)裝(zhuang)(zhuang)(zhuang)效(xiao)(xiao)果(guo)若用室內大(da)(da)線(xian)接(jie)收(shou)到的(de)圖像效(xiao)(xiao)果(guo)較差,而安(an)裝(zhuang)(zhuang)(zhuang)室外衛(wei)星電(dian)(dian)視(shi)(shi)接(jie)收(shou)機時可獲得良好的(de)效(xiao)(xiao)果(guo),則用放大(da)(da)器后仍可使用室內衛(wei)星電(dian)(dian)視(shi)(shi)接(jie)收(shou)機。如果(guo)安(an)裝(zhuang)(zhuang)(zhuang)衛(wei)星電(dian)(dian)視(shi)(shi)接(jie)收(shou)機放大(da)(da)器后,電(dian)(dian)視(shi)(shi)機的(de)收(shou)看效(xiao)(xiao)果(guo)沒有明顯變(bian)化(hua),或者收(shou)看效(xiao)(xiao)果(guo)比(bi)以前差,則是(shi)安(an)裝(zhuang)(zhuang)(zhuang)錯誤所引(yin)起的(de),應(ying)仔細檢(jian)查后再按正確的(de)安(an)裝(zhuang)(zhuang)(zhuang)方法(fa)糾正。
(6)有良好的衛星電視接收機和避雷設備如使用室外衛星電視接收機的電視機用戶需安裝衛星電視接收機放大器,必須有良好的多單元衛星電視接收機與之配合,并要安裝好避雷設備,以防雷擊 。