Motorola SG 2000 Instruções de Operação descarregar pdf (Página 28)

Bench Setup 3

-7

AT&T SLW2500 Installation and Operation Manual

Manual Gain Control

1 Connect a signal level meter to the FORWARD TEST POINT and tune it to a channel near

550 MHz.

2 Position the drive selector to the MAN position. Figure 3-2 illustrates the location of the

AUTO/MAN drive selector.

3 Turn the gain control, MAN ADJ, to maximum (fully clockwise) and then turn it

counterclockwise to reduce the output by 3 dB.

If the output level is greater than required, change the pad at the receiver output location to

obtain the desired level. To calculate the correct pad value, subtract the desired level from

the measured level and increase the pad by that amount.

Thermal Control, Model TCU

1 Perform the steps under Manual Gain Control.

2 Position the drive unit selector to the AUTO position.

3 Turn the level control potentiometer on the TCU to achieve the same output level as in the

MAN position.

Return Path

Figure 3-1 illustrates the location of the return-path transmitter module.

To set up the return-path transmitter:

1 Confirm that the transmitter is installed in the optical transmitter A position.

2 Measure the optical power level at the test point labeled OPTICAL POWER (1V/MW) provided on

the top panel of the transmitter as illustrated in Figure 5-2. The scaled voltage present at

this test point is 1.0 V/mW.

3 Verify that the green ON LED, located on the top panel of the transmitter, is illuminated to

confirm enable status. Refer to Section 5, “Operation,” for FAULT LED functions.

4 Measure the return-path system levels.

The unit is configured to drive the laser to the recommended level (+9 dBmV) when the total

combined power at all ports is approximately +15 dBmV.

For more specific information regarding return path setup procedures, refer to the supplemental

document Return Path Level Selection, Setup, and Alignment Procedure.

Forward Path Padding

The pad values, presented in Table 3-2, serve as a starting-point reference for typical

installations. While this chart is prepared specifically for 77 channel loading, the difference for

110 channel loading is slight, approximately 1 to 2 dB less.

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Motorola SG 2000 Instruções de Operação Página 28