Adtran TRDDS-R Benutzerhandbuch
Page 6
61291021L5-5A
Section 61291021L5-5A, Issue 1
5. DEPLOYMENT GUIDELINES
The TROCU DP and TRDDS-R use technology intended
to eliminate the need for repeaters and concerns over
impairments caused by typical noise and bridged tap.
Listed below are the loop design guidelines for TRDDS
(see Tables 8 and 9 for more information):
to eliminate the need for repeaters and concerns over
impairments caused by typical noise and bridged tap.
Listed below are the loop design guidelines for TRDDS
(see Tables 8 and 9 for more information):
• All loops must be nonloaded.
• Actual Measured Loss (AML) should not exceed 50
dB at 13.3 kHz (135
Ω
termination), the Nyquist
frequency of TRDDS.
NOTE
The 50 dB AML limit includes 6 dB of signal
margin to account for potential near-end cross
talk (NEXT) from other digital services that may
be provisioned in the same binder group.
margin to account for potential near-end cross
talk (NEXT) from other digital services that may
be provisioned in the same binder group.
•
Loop length should not exceed 50 kft.
•
Bridged tap length should not exceed 12 kft.
•
Background noise level should not exceed
34 dBrn.
34 dBrn.
•
Impulse noise should not exceed
-40 dBm, (+50 dBrn).
-40 dBm, (+50 dBrn).
NOTE
Measure noise with 50 kbit weighting
characteristic approximating a filter with a
passband of 40 Hz to 30 kHz. Background noise
level or impulse noise level is referenced from 56/
64 kbps data rate in TR62310.
characteristic approximating a filter with a
passband of 40 Hz to 30 kHz. Background noise
level or impulse noise level is referenced from 56/
64 kbps data rate in TR62310.
Figure 7. Total Reach Dataport Bidirectional
Loopback Normal Mode
DSU/CSU
TRDDS-R
Total Reach
Dataport
Open Loop
Bidirectional
loopback
X
X
If the TRDDS-R detects a bidirectional loopback during
power-up synchronization, the TRDDS-R allows data to pass
on the four-wire interface by entering pass-thru mode. This
permits a standard, portable DDS test set, connected to the
four-wire customer interface of the TRDDS-R, to verify the
integrity of the two-wire loop by transmitting a test pattern
and examining the returning data for synchronization and
errors. The TRDDS-R LBK indicator always flashes during
a Total Reach dataport bidirectional loopback in the pass-thru
mode. Refer to Figure 6 for an illustration of the bidirectional
loopback pass-thru mode.
power-up synchronization, the TRDDS-R allows data to pass
on the four-wire interface by entering pass-thru mode. This
permits a standard, portable DDS test set, connected to the
four-wire customer interface of the TRDDS-R, to verify the
integrity of the two-wire loop by transmitting a test pattern
and examining the returning data for synchronization and
errors. The TRDDS-R LBK indicator always flashes during
a Total Reach dataport bidirectional loopback in the pass-thru
mode. Refer to Figure 6 for an illustration of the bidirectional
loopback pass-thru mode.
If a Total Reach dataport bidirectional loopback is invoked
after the TRDDS-R achieves synchronization, the TRDDS-R
will not pass or receive data from the CPE or DDS test set.
This is consistent with current DDS testing methods and is
referred to as the Total Reach dataport bidirectional loopback
normal mode. For testing purposes, the installer may choose
to initiate the TRDDS-R to pass-thru mode. Once the
bidirectional loopback is executed in normal mode, unseat
and reseat the TRDDS-R and allow the unit to train-up. Once
trained, the TRDDS-R will revert to pass-thru mode for
further testing. Refer to Figure 7 for TRDDS operation
during bidirectional loopback in normal mode.
after the TRDDS-R achieves synchronization, the TRDDS-R
will not pass or receive data from the CPE or DDS test set.
This is consistent with current DDS testing methods and is
referred to as the Total Reach dataport bidirectional loopback
normal mode. For testing purposes, the installer may choose
to initiate the TRDDS-R to pass-thru mode. Once the
bidirectional loopback is executed in normal mode, unseat
and reseat the TRDDS-R and allow the unit to train-up. Once
trained, the TRDDS-R will revert to pass-thru mode for
further testing. Refer to Figure 7 for TRDDS operation
during bidirectional loopback in normal mode.
Figure 6. Total Reach Dataport Bidirectional
Loopback Pass-Thru Mode
Test Unit
TRDDS-R
Total Reach
Dataport
Data
Pass-Thru
Bidirectional
loopback
Table 7. Total Reach Dataport Loopbacks
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