
PRELIMINARY
XRT79L71
370
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
The Transmit Section of the XRT79L71 would then accept these ATM cells and it would (once again) map
these ATM cells back into an E3 data-stream. The XRT79L71 would output a E3 line signal, which would be
routed back into the Receive Input of the Adtech AX-4000 Tester.
The Adtech AX-4000 Tester can determine whether or not bit-errors have occurred in the loop-back path
(through the Flat-Loss Attenuators, the Cable Simulator, and the XRT79L71 Evaluation Board) by checking for
E3 alarms, occurrences of HEC Byte errors (within ATM cells) and/or pattern sync errors within the ATM cell
payload, etc.
Test Results
The Receive Sensitivity Test Results are summarized below in Table 45.
5.3.1.9.2
Interference Margin Capability of the Receive E3 LIU Block
The purpose of an Interference Margin Test (or specification) is to verify that the Receive DS3/E3 LIU Block
(within the XRT79L71) can tolerance a certain amount of inband noise and still properly receive a DS3 or E3
signal.
ITU-T G.703 mandates that an E3 Receiver be designed such that it will have an interference margin of at least
20dB. As a consequence, we have specifically designed the Receive DS3/E3 LIU Block such that it will have
sufficient Interference Margin in order to meet both the ITU and our Customer's requirements.
This particular section documents the Interference Margin capability of the Receive DS3/E3 LIU Block, for E3
applications.
Test Approach
The basic test configuration used for "Interference Margin" measurements is illustrated below in Figure 172.
TABLE 45: RECEIVE SENSITIVITY TEST RESULTS (E3 APPLICATIONS)
TEST
NUMBER
POWER SUPPLY VOLTAGE
RECEIVE SENSITIVITY
COMMENTS
1
3.15V
16.7dB of Cable Loss
2
3.30V
16.7dB of Cable Loss
3
3.45V
16.7dB of Cable Loss
FIGURE 172. ILLUSTRATION OF TEST SET-UP USED TO TEST THE XRT79L71 FOR INTERFERENCE MARGIN
CERJAC
156MTS
Tester
CERJAC
156MTS
Tester
Flat Loss
Attenuator
Flat Loss
Attenuator
Cable
Simulator
Cable
Simulator
XRT79L71
Evaluation
Board
XRT79L71
Evaluation
Board
Function
Generator
Function
Generator