Configuring DIP switch S1

Switches S1-1 through S1-8 are used to configure clocking modes and line coding. Default settings of the switches are shown in Table 1. Descriptions of the switch options follow the table.

Table 1: Switch S1 summary

Position

Function

Default Setting

Selected Option

 

 

 

 

S1-1

HDB3(E1)/B8ZS(T1) or

OFF

HDB3(E1)/

 

AMI Line Coding

 

B8ZS(T1)

 

 

 

 

S1-2

T1 Line Buildout

ON

0 dB

S1-3

T1 Line Buildout

ON

 

 

 

 

 

S1-4

Reserved

 

 

 

 

 

 

S1-5

Reserved

 

 

 

 

 

 

S1-6

Clock Mode

OFF

Network

 

 

 

 

S1-7

 

ON

 

 

 

 

 

S1-8

Reserved

 

 

 

 

 

 

Switch S1-1: Line Coding Options. Use switches S1-1 to determine the line coding of the network interface ports. The setting should be HDB3 if your unit is an1194/E1, B8ZS if your unit is an 1194/T1, or AMI (common to both T1 and E1 technologies) The line coding must be the same line coding prescribed by the network access provider (NAP). Most applications will use HDB3.

S1-1Setting

ONAMI

OFF

HDB3 (E1)/B8ZS(T1)

•Alternate Mark Inversion (AMI): AMI defines a pulse as a “mark,” a binary one, as opposed to a zero. In an E1 Network connection, sig- nals are transmitted as a sequence of ones and zeros. Ones are sent as pulses, and zeros are sent as spaces, i.e., no pulse. Every other pulse is inverted from the previous pulse in polarity, so that the signal can be effectively transmitted. This means, however, that a long sequence of zeros in the data stream will cause problems, since the modem receiving the signal relies on the signal to recover the clock. If you must use AMI, ensure that the data terminal equipment connected to the unit provides a minimally acceptable pulse density. AMI coding does not inherently account for ones density. To meet this requirement, ensure that the data inherently meets pulse density.

•High Density Bipolar 3 (HDB3): In HDB3 coding, the transmitter deliberately inserts a bipolar violation when excessive zeros in the data stream are detected. The receiver recognizes these special viola-

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