XRT86VL3X_07 datasheet(61/153 Pages) EXAR

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XRT86VL3X

REV. 1.2.2

T1/E1/J1 FRAMER/LIU COMBO - ARCHITECTURE DESCRIPTION

6.1.3

Cable Loss Indicator

The ability to monitor the cable loss attenuation of the receiver inputs is a valuable feature. The XRT86VL3x

contains a per channel, read only register for cable loss indication. CLOS[5:0] is a 6-Bit binary word that

reports the value of cable loss in 1dB steps with an absolute accuracy of ±1dB. An example of -25dB cable

loss attenuation is shown in Figure 57.

6.2

Receive Sensitivity

To meet Long Haul receive sensitivity requirements, the XRT86VL3x can accept T1/E1/J1 signals that have

been attenuated by 43dB cable attenuation in E1 mode or 36dB cable attenuation in T1 mode without

experiencing bit errors, LOF, pattern synchronization, etc. Short haul specifications are for 12dB of flat loss in

E1 mode. T1 specifications are 655 feet of cable loss along with 6dB of flat loss in T1 mode. The XRT86VL3x

can tolerate cable loss and flat loss beyond the industry specifications. The receive sensitivity in the short haul

mode is approximately 4,000 feet without experiencing bit errors, LOF, pattern synchronization, etc. Although

data integrity is maintained, the RLOS function (if enabled) will report an RLOS condition according to the

receiver loss of signal section in this datasheet. The test configuration for measuring the receive sensitivity is

shown in Figure .

FIGURE 56. SIMPLIFIED BLOCK DIAGRAM OF THE EQUALIZER AND PEAK DETECTOR

FIGURE 57. SIMPLIFIED BLOCK DIAGRAM OF THE CABLE LOSS INDICATOR

Peak

Detector &

Slicer

Rx Equalizer

Control

RTIP

RRING

-25dB of Cable

Loss

Equalizer and

Peak Detector

CLOS[5:0] = 0x19h

(25dec = 19hex)

-25dB Attenuated

Signal

Read Only

XRT86VL3x

XRT86VL3X Datasheet(PDF) 61 Page - Exar Corporation