AT&T Telephone DS1/DMi/ISDN-PRI Uživatelský manuál stáhnout pdf (Strana 89)

100

101

THE DIGITAL LOSS PLAN

4-7

OPS Ports

Analog off-premises station (OPS) facility requirements specify a loss not to exceed 4 dB in each

direction. To provide for transmission stability (eliminate singing and echo) with D4-channel units,

at least 1 dB of loss in both directions is required from the 2-wire analog hybrid terminals. Foreign

exchange subscriber end channel units (FXSs) provide losses adjustable from 1.0 through 1.8 dB.

This capability permits their use with analog facilities having losses as great as 3 dB, giving a net loss

of 4 dB. FXS end with gain transfer channel units (FXS/GTs) make available an additional 2-wire

gain of 6 dB, permitting their use with analog facilities with losses as great as 9 dB. Attenuator,

equalizer, and balance settings should be made with the engineering data listed on the circuit detail

record.

Refer to D4-Channel Bank Channel Units — Application Engineering/Carrier Engineering (855-351-

105) for engineering design information as well as switch settings and application notes on D4-

channel units.

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AT&T Telephone DS1/DMi/ISDN-PRI Uživatelský manuál Strana 89

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