ADTRAN HDSL4 Manuel d'utilisateur télécharger pdf (Page 19)

1961181412L1-5B

6. HDSL4 DEPLOYMENT GUIDELINES

The different segments of an HDSL4 circuit are

defined in Figure 24.

NOTE

Refer to the Detailed Status Screen (Main Menu

selection “3,” Span Status selection “1”) for the

current loop SNR Margin, Insertion Loss, and

Pulse Attenuation status.

Each of the three segments associated with span

powering two H4Rs and an H4TU-R must satisfy the

recommended insertion loss, loop attenuation

requirements in addition to the DC resistance budgets.

In general, 22 and 19 AWG segments will be

restricted by their loop attenuation while the DC

resistance will restrict the segment reach for 26 and 24

AWG. When designing a dual H4R loop, the first

segment should have lower DC resistance than the

second segment. Single H4R spans do not require any

restriction due to DC resistance.

The segment resistance (Ω

segment

) is determined using

the equation provided below.

Ω

segment

= L

* Ω

+ L

* Ω

+ L

* Ω

+ L

* Ω

where : L

is the length of # AWG cable (kft.,

excluding bridge taps), Ω

is the DC

Resistance of # AWG cable

Table 6 list single pair cable DC resistance values to

be used in the equation above.

Once the resistance of each segment is confirmed, see

Figure 25 to decide if the H4TU-C is capable of span

powering two H4Rs and one H4TU-R. Follow these

steps to utilize the graph shown in Figure 25:

1. Find the line on the graph which represents the

known third segment resistance. These are the

lines running diagonally across the graph labeled

300 - 1100 ohms. This line represents the upper

limit for two H4Rs plus H4TU-R span powering.

Figure 24. HDSL4 Circuit Segments

1st Segment

H4TU-C 1st H4R 2nd H4R H4TU-R

2nd Segment 3rd Segment

According to the number of H4Rs in the HDSL4

circuit, the following service ranges apply:

• HDSL4 circuit containing no H4Rs will reach up

to 15,250 ft on the local loop (24 AWG) [10,800

ft for 26 AWG]

• HDSL4 circuit containing one H4R will reach up

to 15,250 ft on the first segment and 15,050 ft on

the second segment (24 AWG) [10,550 ft for 26

AWG]

• HDSL4 circuit containing two H4Rs will reach to

12 kft on the first segment, 13.5 kft on the second

segment, and 15 kft on the third segment (24

AWG) *

*This is one example of a circuit with two H4Rs. Other loop

length configurations are possible in compliance with loop

resistance restraints (90

F).

NOTE

DSL Assistant must be used to engineer HDSL4

circuits with two repeaters.

The ADTRAN HDSL4 system provides DS1-based

services over loops designed to comply with the

guidelines given below. These guidelines apply to the

first segment in the circuit (between the H4TU-C and

the first H4R) or an HDSL4 circuit with no H4Rs.

1. All loops are nonloaded only.

2. Any single bridged tap is limited to 2 kft.

3. Total bridged tap length is limited to 2.5 kft.

4. Insertion Loss: See Table 5 for loop insertion

loss requirements.

5. Loop Attenuation:

Upstream Downstream

segment 31 dB 33 dB

segment 30 dB 30 dB

Table 5. HDSL4 Loop Insertion Loss Values

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)zHk(

tnemgeSts1

)Bd(ssoL

tnemgeSdn2

)Bd(ssoL

055.139.92

083.535.33

0311.931.73

6910.24A/N

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 31 32

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ADTRAN HDSL4 Manuel d'utilisateur Page 19

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