User manual

Release 2.2 Digium, Inc. Page 38

Chapter 3: Configuration

Choose 1 to make the equipment at the far end of the E1/T1 link the

preferred source of the master clock. Choose

2 to make it the second

choice for the master clock, if the first choice port fails (the far end

dies, a cable breaks, etc.). Choose 3 to make a port the third choice,

and so on. If you have, for instance, 2 ports connected to the PSTN,

mark those as 1 and 2. The number used for each port should be

different.

If you choose 0, the port will never be used as a source of timing. This

is appropriate when you know the far end should always be a slave to

you. If the port is connected to a channel bank, for example, you

should always be its master. Any number of ports can be marked as 0.

Incorrect timing sync may cause clicks/noise in the audio, poor

quality or failed faxes, unreliable modem operation, and dropped calls.

The line build-out (or LBO) is an integer, from the following:

0: 0 db (CSU) / 0-133 feet (DSX-1)

1: 133-266 feet (DSX-1)

2: 266-399 feet (DSX-1)

3: 399-533 feet (DSX-1)

4: 533-655 feet (DSX-1)

5: -7.5db (CSU)

6: -15db (CSU)

7: -22.5db (CSU)