User's Manual

DART Modules
Page 30 FlexWave Prism Element Management System 7.1 User Manual
©
2011 ADC Telecommunications, Inc ADCP-77-177 • Issue 1 • July 2011
Simulcast Groups
Simulcast combining occurs when more than one Remote DART is linked to the
same Host DART. The gains of the reverse signals are reduced before summation
to prevent over-flow when the digital signals are added together. This simulcast
gain reduction is accomplished as a function of the number of Remote DARTs
linked to the Host DART (N) and the selected Reverse Gain Mode:
• Mode 1 (Noise Floor Matching)—uses an algorithm that normalizes the noise floor of
all Remote Units.
• Mode 2 (Legacy Prism/URH)—reduces the gain by 20*log10(N).
• Mode 1 (Noise Floor Matching) uses an algorithm that normalizes the noise floor
of all Remote Units.
• Mode 2 (Legacy Prism/URH)—reduces the gain by 20*log10(N).
Table 6 illustrates gain reduction for Mode 1 and Mode 2.
Simulcast groups are restricted to using the same timeslots on the fibers to each
Remote. For example, if the first link established in a simulcast group is using
timeslots 1-3 on a fiber for the PCS A passband, timeslots 1-3 must be used for
that passband on each of the other Remotes in the simulcast group. If timeslots
1-3 are not available on a Remote's fiber, the Remote cannot be added to the
simulcast group.
To minimize timeslot conflicts, simulcast groups should be configured before other
passbands. If a conflict occurs while attempting to link a DART, an error message
displays indicating that the DART linking failed. The DART using the conflicting
timeslots must be unlinked to allow the DART in the simulcast group to be linked.
Table 6. Reverse Gain Mode and Gain Reduction
# Remote
DARTs
Reduction (dB)
Mode 1 Mode 2
1 0 0
2 3.0 6.0
3 4.7 9.5
4 6.0 12.0
5 7.0 14.0
6 7.8 15.6
7 8.3 16.9
8 9.0 18.0