Zyxel VES-1616FE-55A [101/318] Dpbo electrical length

Chapter 13 xDSL Port Setup

VES-1616FE-55A User’s Guide

101

An example is shown next. VDSL Line 1 and ADSL Line 2 are in the same binder. Crosstalk

occurs when the ADSL signal flows from CO (B) and is near to CO (A)’s ONU (Optical

Network Unit) location. Besides, higher Line 1 PSD causes higher interference to the Line 2.

CPE (B) receives signal with higher attenuation. With DPBO enabled on the CO (A), it

decreases the PSD level and reduces the crosstalk impact on other service lines.

Figure 54 DPBO Resolves Downstream Far-End Crosstalk

13.4.9 DPBO Electrical Length

The distance between a cabinet and the central office is an important parameter of DPBO

settings as we mentioned in the Section 13.4.8 on page 100. The electrical length is used

instead of the real physical distance according to G.997.1 format. Depending on the cable type

the line used and physical line length, you can calculate the electrical length (in dB). For

example, the distance is 1 kilometer and you use 24 AWG cable type, the electrical length 20.5

dB is suggested to used.

The following table displays the calculation from a real length to an electrical length.

VDSL

CPE (B)

Line1 (150m)

Line2 (600m)

No-DPBO

DPBO

ADSL

CO (A)

ADSL

CPE (A)

VDSL

CO (B)

Table 21 Real Length to Electrical Length

CABLE TYPE REAL LENGTH TO ELECTRICAL LENGTH A B C

22 AWG =16.2*(cable length in kilometer) 0 0 0

24 AWG =20.5*(cable length in kilometer) 0 1 0

26 AWG =25.8*(cable length in kilometer) 0 1.0039065 -0.0039065