XRT75VL00D datasheet(35/92 Pages) EXAR

tên linh kiện	XRT75VL00D

Giải thích chi tiết về linh kiện	E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER

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XRT75VL00D

REV. 1.0.3

E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER

DISABLING ALOS/DLOS DETECTOR:

For debugging purposes it is useful to disable the ALOS/DLOS detector. Writing a “1” to the ALOS and DLOS

bits disables the LOS detector on a per channel basis.

5.4.2

E3 LOS Condition:

If the level of incoming line signal drops below the threshold as described in the ITU-T G.775 standard, the

LOS condition is detected. Loss of signal level is defined to be between 15 and 35 dB below the normal level. If

the signal drops below 35 dB for 175 ± 75 consecutive pulse periods, LOS condition is declared. This is

illustrated in Figure 19.

TABLE 10: THE ALOS (ANALOG LOS) DECLARATION AND CLEARANCE THRESHOLDS FOR A GIVEN SETTING OF

REQEN (DS3 AND STS-1 APPLICATIONS)

APPLICATION

REQEN SETTING

SIGNAL LEVEL TO DECLARE ALOS

SIGNAL LEVEL TO CLEAR ALOS

DS3

1<20mV

>90mV

STS-1

1<25mV

>115mV

FIGURE 19. LOSS OF SIGNAL DEFINITION FOR E3 AS PER ITU-T G.775

0 dB

-12 dB

-15dB

-35dB

Maximum Cable Loss for E3

LOS Signal Must be Declared

LOS Signal Must be Cleared

LOS Signal may be Cleared or Declared

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