Specifications

FOM-40 Installation and Operation Manual Chapter 5 Troubleshooting and Diagnostics

Internal BERT 5-5

Modem Self-Test

The modem self-test checks that the modem is operating correctly (see Figure 5-4).

Pattern

Generator

PATT

Pressed

ANA

Pressed

Transmitter

Receiver

FOM-40

Pattern

Tester

ERR

Figure 5-4. Modem Self-Test



To perform the modem self-test:

1. Press the ANA pushbutton on the front panel.

The TEST and DCD LEDs light.

If the DCD indicator does not light, verify that the DCD switch SW5/8 is set to ON,

or that the RTS signal is High.

2. Press the PATT pushbutton. Verify that:

 DCD and TEST LEDs are ON.

 ERR LED blinks once.

Continuous errors cause the ERR LED to light and stay lit, intermittent errors

cause ERR to blink. FOM-40 is faulty and should be replaced.

3. To stop the test, restore all pushbuttons to their normal positions.

Two-BER Test

The Two-BER Test checks the link between the units (see Figure 5-5).



To perform the two-BER test:

• Press the PATT button on both devices.

Continuous errors cause the ERR LED to light and stay lit, intermittent errors

cause ERR to blink. FOM-40 is faulty and should be replaced.

For correct operation of the BER Test, the DCD switch (SW5/8) must be set to OFF

or the RTS signal must be High.

When the PATT pushbutton is pressed, the external BERT is effectively disconnected.

Note