7.5 Input power limit function (TX Input ALC) The DAS has TX input ALC function at the BIU to limit level when input power is increased above level by operated input AGC function Normally, there ara more than two input port in tha MDBU of BIU For example, 850cellular band has two input port to support both VzW and AT&T Two input power may be different each other. The DAS have input attenuator in first stage of MDBU. Through input AGC function, input ATT is adjusted according to input power. If input power increase, input ATT is adjusted again to limit increased input power. Also, if input power decrease input ATT return to initial ATT 7.6 Optic loss compensation The DAS has the function of automatically compensating for optical loss. It can do the work for up to S5dBo of optical loss. Sat TX OPTIC COMP" of ROU as "ON." Optical compensation of ROU can not be made without communication with such units in upper level as ODU or OEU. For 1dBo of optical loss, basic TX OPTIC ATT is 12dB; for 5dBe of optical loss, TX OPTIC ATT is 4dB. OPTIC COMP works only ona time before it stays dormant. The figure below shows a screen for OPTIC Information in ROU GUI. LD POWER means output level of ROU Laser Diode, which is sent to a upper unit by ROU. PD POWER means input level of Photo Diode to ba received from a upper unit. OPTIC Information LD POWER @ 75 dBm PD POWER @ -2.0 dBm TX OPTIC ATT 2.5 d Ts PTI Corr OFF RESULT Success During optical compensation, the Result window shows Processing and then a result value. There are three types of results as follows:
1. Success: The optical compensation is normally competed 2. Over Optic Lass: Genarated optical loss exceed S5dBo or more. 3. Communication Fail: Communication with ROU is under poor condition. Confidential & Proprietary 128/128