O p e r a t i o n

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Manual Control Board

The SG 2000 manual control board (SG2-MCB) serves to locally control redundancy functions and ingress switch operation if a status monitor is not installed. Figure 3-2 illustrates the MCB board mounted on the main RF board in place of the status monitor. Inputs to the MCB are the received optical power signals from both the A and B receivers, scaled at 1 V/mW.

The MCB board contains two 3-gang, dual-in-line-package (DIP) switches and five screwdriver adjustable potentiometers. Table 5-11 provides descriptions and functions of these user-interface settings:

Table 5-11

MCB user-interface settings

Description

Function

Switch S1-1

Determines whether the primary/redundant reset state occurs at 0.5 dB or

 

1.0 dB more than the defined optical level threshold. This hysteresis or “gap”

 

prevents the automatic switch-over function from “hunting” or switching

 

back and forth if the received optical power remains close to the switching

 

threshold. The factory setting is 1.0 dB.

Switch S1-2

Enables selection of either normal (NORM) or manual override (OVER)

 

operation. In the NORM position, switchover between the primary and

 

secondary optical paths is automatically controlled by the received optical

 

power of the primary receiver. In the OVER position, the selection is

 

performed manually using switch S1-3. The factory setting is NORM.

Switch S1-3

Selects either receiver A (RXA) or receiver B (RXB) as the primary optical

 

receiver when S1-2 is in the NORM position. With S1-2 in the OVER position,

 

S1-3 manually enables either receiver. The factory setting is RXA.

Switch S2-1

Selects standard slaving or cross slaving of the transmitters to the

 

receivers. Set in the standard slaving (STD_SLV ) position, with switch S1-2

 

in the NORM position, transmitter A follows the enable/disable status of

 

receiver A, and transmitter B that of receiver B. Setting S2-1 to cross

 

slaving (CRS_SLV) causes transmitter B to be on when receiver A is

 

enabled and transmitter A to be on when receiver B is enabled. The factory

 

setting is STD_SLV.

Switch S2-2

Controls the status of return transmitter A. If S1-2 is in the OVER position,

 

S2-2 either enables transmitter A (TXA_EN) or disables transmitter A

 

(TXA_DIS). If S1-2 is in the NORM position, then S2-2 enables slaving of the

 

transmitter status to the corresponding receiver (TXA_DIS) or overrides the

 

slaving function enabling the transmitter to be on continuously (TXA_EN).

 

The factory setting is TXA_DIS.

Switch S2-3

Performs the same function for transmitter B as S2-2 performs for

 

transmitter A. The factory setting is TXB_DIS.

Alarm potentiometer

(ALRM) sets the received optical power threshold at which automatic

 

switchover from the primary to the secondary path occurs. It can be set for

 

any power level up to 2.5 mW (+4 dBm). The factory setting is 0.25 V

 

(-3 dBm).

SG 2000 Installation and O peration Manual

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Motorola SG 2000 operation manual Manual Control Board, Description Function