使用無線系統時需要避免的五種錯誤?
1. 信號阻塞
盡量使發射機天線和接收機天線之間能夠相互看見。在接收天線及其關聯發射機之間應避免有金屬物體、墻體或大量人群。理想情況下,接收天線應與發射機同處一室,并置于比觀眾或其他障礙高的位置。
人體也可(ke)能干擾無線信號(hao)。我們(men)的(de)身(shen)體大部分由水(shui)構(gou)成,會吸收射頻(pin)信號(hao)。另外,如(ru)(ru)果用(yong)戶用(yong)手握住手持(chi)式發射機的(de)外置天線部分,則(ze)可(ke)能使(shi)其(qi)有效輸出(chu)降低50%以上。類似,如(ru)(ru)果腰包式發射機上的(de)柔性天線卷曲或者折(zhe)疊(die),也可(ke)能使(shi)信號(hao)受損。
2. 天線類型錯誤或放置不當
在無線(xian)話筒操作中,接(jie)(jie)收(shou)(shou)(shou)機天線(xian)是(shi)最容易令人誤解的(de)地方(fang)。天線(xian)選擇、放(fang)置(zhi)或配線(xian)等方(fang)面的(de)失誤都可能導致接(jie)(jie)收(shou)(shou)(shou)信號(hao)范圍偏短、演出區死角,也可能在接(jie)(jie)收(shou)(shou)(shou)機端導致低信號(hao)強度問題,結(jie)果致使信號(hao)經常丟失。現(xian)代分集接(jie)(jie)收(shou)(shou)(shou)機比單天線(xian)型號(hao)的(de)性能要好(hao)得多,但是(shi),要最大限度地提高系統的(de)性能和可靠性,仍然(ran)需要選擇正(zheng)確的(de)天線(xian)并安放(fang)到正(zheng)確的(de)位置(zhi)。
3. 協調不當的頻率集
協調得當的無線頻率集必須滿足兩個條件:
1) 使用 頻點必須避開當地的活動電視頻道
2) 頻點必(bi)須(xu)相互(hu)兼容
4. 電池管理不當
盡管發射機電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)的(de)(de)壽(shou)命(ming)是(shi)(shi)無線(xian)話筒的(de)(de)一個大(da)問(wen)題,用(yong)戶們仍然嘗試(shi)使(shi)用(yong)廉(lian)價(jia)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)以(yi)削(xue)減運營成本(ben)。多數無線(xian)系統(tong)制(zhi)造(zao)商指定(ding)要使(shi)用(yong)一次(ci)性堿(jian)性或鋰電(dian)(dian)(dian)(dian)(dian)(dian)池(chi),因(yin)為(wei)這(zhe)類電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)的(de)(de)輸出電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)在其(qi)整個壽(shou)命(ming)中可以(yi)保持非(fei)常(chang)(chang)穩定(ding)。這(zhe)非(fei)常(chang)(chang)重要,因(yin)為(wei)多數發射機在電(dian)(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)較(jiao)低時,會出現可聽見的(de)(de)失真(zhen)或信號(hao)丟失現象。雖然可充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)似乎是(shi)(shi)理想的(de)(de)解決(jue)方案(an),但許多充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)卻比一次(ci)性電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)低20%左右,即便是(shi)(shi)完(wan)全充(chong)滿電(dian)(dian)(dian)(dian)(dian)(dian)也是(shi)(shi)如此。
5. 增益設置不當
在無線(xian)話(hua)筒系統中(zhong),正確設(she)置(zhi)輸入(ru)增益(yi)(yi)是最重(zhong)要的調(diao)整之一(yi)。如果增益(yi)(yi)設(she)得過高,可(ke)能發生失真現象,如果增益(yi)(yi)設(she)得太(tai)低(di),則(ze)可(ke)能導致信噪比欠佳(jia)問(wen)題。多(duo)數(shu)無線(xian)系統在發射機(ji)上提(ti)供有增益(yi)(yi)控(kong)制功(gong)能,體(ti)現為物理開(kai)關、電(dian)位器(qi)或可(ke)編程調(diao)節功(gong)能。不(bu)妨把這(zhe)種增益(yi)(yi)控(kong)制功(gong)能類比為混(hun)音器(qi)上的"微調(diao)"或"增益(yi)(yi)"調(diao)節功(gong)能。其目的是將輸入(ru)靈(ling)敏度設(she)得低(di)以(yi)(yi)避免(mian)輸入(ru)過載(zai)或"削波",同時又要設(she)得高以(yi)(yi)使信號電(dian)平遠遠超過系統背景(jing)噪聲。
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