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User Reference and Installation Guide
2-19
© 2006 Microwave Data Systems Inc.
All Rights Reserved.
MDS
Digital Radio
Series
05-4561A01, Rev. A
Connected to
east modem
Connected to
west modem
Connected to
east modem
Connected to
west modem
Connected to
west modem
Connected to
east modem
Connected to
west modem
Connected to
east modem
Figure 2-7. 2+0 (East-West) configuration.
2.8 1+1 Protection
The MDS Digital Radio Series supports 1+1 protection as an option for a critical link. In this
configuration, protection is provided in a single 1 RU chassis. The SDIDU
TM
contains two power
supplies and two modems. The power supply, ODU, IF/telemetry and modem are protected. The
digital framing and LIUs are not. One modem is referred to as the west modem and the other as
the east modem. 1+1 protection can be run in two modes called diversity and non-diversity.
In diversity mode, the link between each pair of modems is the same, as shown in
168H 165H
Figure 2-8,
providing complete redundancy. This arrangement requires bandwidth for both links and non-
interference between the links, but it provides hitless receive and transmit switching. The
SDIDU
TM
supports both frequency and spatial diversity. In frequency diversity, two frequencies
are used. In spatial diversity, two non-interfering paths are used. In either case, the proprietary
framer chooses the best, or error-free, data stream and forwards it to the Line Interface Units
(Luis).
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