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XR-T7295IW

DS3/Sonet STS-1 Integrated Line Receiver

Exar Corporation 

XR-T7295

DS3 SIGNAL REQUIREMENTS AT THE DSX

Pulse characteristics are specified at the DSX-3, which is

an interconnection and test point referred to as the

cross-connect (see Figure 2.) The cross-connect exists

at the point where the transmitted signal reaches the

distribution frame jack. Table 2 lists the signal

requirements. Currently, two isolated pulse template

requirements exist: the ACCUNET T45 pulse template

(see Table 3 and Figure 4) and the G.703 pulse template

(see Table 4 and Figure 5). Table 3 and Table 5 give the

associated boundary equations for the templates. The

XR-T7295 correctly decodes any transmitted signal that

meets one of these templates at the cross-connect.

Parameter

Line Rate

Line Code

Test Load

Pulse Shape

Power Levels

Specification

44.736 Mbps 20 ppm

Bipolar with three-0 substitution (B3ZS)

75 Ω 5%

An isolated pulse must fit the template in Figure 4 or Figure 5.1 The pulse amplitude may be scaled by

a constant factor to fit the template. The pulse amplitude must be between 0.36vpk and 0.85vpk,

measured at the center of the pulse.

For and all 1s transmitted pattern, the power at 22.368 $ 0.002MHz must be -1.8 to +5.7dBm, and

the power at 44.736 $0.002MHz must be -21.8dBm to -14.3dBm.2, 3

Notes

1 The pulse template proposed by G.703 standards is shown in Figure 5 and specified in Table 4. The proposed G.703 standards

further state that the voltage in a time slot containing a 0 must not exceed $ 5% of the peak pulse amplitude, except for the residue

of preceding pulses.

2 The power levels specified by the proposed G.703 standards are identical except that the power is to be measured in 3kHz bands.

3 The all 1s pattern must be a pure all 1s signal, without framing or other control bits.

Table 2. DSX-3 Interconnection Specification

Lower Curve

Time

Equation

T  -0.36

-0.36  T  +0.28

0

0.5 ƪ1+sin π/2 [1+T/0.18]ƫ

0.28  T

0.11e-3.42(T-0.3)

Upper Curve

Time

Equation

T-0.68

-0.68  T +0.36

0

0.5 ƪ 1+sinπ/2 [ 1+T/0.34]ƫ

0.36  T

0.05 + 0.407e-1.84(T-0.36)

Table 3. DSX-3 Pulse Template Boundaries for ACCUNET T45 Standards (See Figure 4.)

Rev. 1.05

7

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