User Manual

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ADCP-75-179 • Preliminary Issue A • September 2004 • Section 4: maintenance

Page 4-16

7. Connect the input (transmitter) end of the optical fiber to the transmitting HU or STM

(see Figure 4-2).

8. At the transmitting HU or STM, place the On/Off switch in the ON position (press I).

9. Using the transmitting HU or STM as an optical light source, measure the optical power

at the receiver end of the optical fiber. The power level of the optical input signal at the

HU or STM must fall within the following ranges:

Forward Path Signal at the STM: –15 to –25 dBm (with attenuator installed)

Reverse Path Signal at the HU: –13 to –25 dBm (with attenuator installed)

If the power level of the received optical signal is within the specified range, the optical

fiber and the far end unit are good. If the power level of the received signal is not with

the specified range, either the optical fiber is faulty or the far end unit optical transmitter

is faulty. Continue with test procedure to isolate the problem

10. At the transmitting HU or STM, place the On/Off switch in the OFF position (press O).

11. Disconnect the optical power meter from the receiver end of the optical fiber.

12. Use a 1 meter patch cord to connect the optical power meter to the transmitting HU or

STM as shown in Figure 4-3.

Figure 4-3. Host Unit and STM Optical Transmitter Test Set Up

13. At the transmitting HU or STM, place the On/Off switch in the ON position (press I).

14. Measure the optical output power of the transmitting HU or STM. The power level of the

optical output signal from the HU or STM must meet the following specification:

Forward Path Signal at the HU: 0 +

1 dBm

Reverse Path Signal at the STM: +2 +

1 dBm

If the power level of the optical output signal is within specifications with a 1 meter

patch cord installed, the fiber optic link is faulty. If the power level of the optical signal

is not within specifications, the far end HU or STM optical transmitter is faulty.

HOST UNIT

STM

OPTICAL POWER

METER

OPTICAL POWER

METER

+2 +/- 1 dBm

0 +/- 1 dBm

HOST UNIT OPTICAL TRANSMITTER

TEST SET UP

STM OPTICAL TRANSMITTER

TEST SET UP

1 METER PATCH CORD

20018-A

FWD

(PORT 1)

REV

(PORT 2)

FWD

(PORT 1)

REV

(PORT 2)