7705 SAR Interfaces
178
Interface Configuration Guide
3HE 11011 AAAC TQZZA Edition: 01
A VCB SCADA bridge is created using the config>scada bridge-id command and a
branch is created using the config>scada>branch branch-id command.
3.6.5.1 VCB Applications
VCB can be configured in one of four applications. These applications are set at the
card level. Each application uses a bridging algorithm that determines which
branches control the management of the bridge and transmission of signals:
•VCB
One branch talks and all other branches on the bridge can hear.
• broadcast
Only one branch on the bridge (fixed as branch 1) has control of the bridge to
transmit, and all other branches are in listen-only mode.
• VCB branch initiate
Branches on the bridge are only enabled (unmuted) when the attached base
station signals its presence by grounding the M-lead on the interface connected
to the bridge. Upon receiving the grounded M-lead via T1/E1 ABCD bits or TDM
PW signaling, the bridge unmutes the associated branch. When the ground is
removed, the branch is muted again.
• teleprotection
Each teleprotection relay transmits state information on discrete frequencies so
that each relay can both hear what the other relays are transmitting as well as
transmit its own information to the other relays.
3.6.5.2 Gain
Gain is the increase or decrease in signal power or voltage that occurs in transmitting
a signal from one point to another. The two types of gain are:
• input
• output
Gain is configured at the branch level.
Note: Larger bridges can be built by cascading individual bridges internally within a single
Integrated Services card. Larger bridges can be cascaded across multiple Integrated
Services cards by using an E&M link or a channel group encapsulated for cem (TDM).
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