User's Guide

2 2 2 . Syst em Descr iption
© 2 0 0 7 M ose ley, I nc. All Rights Re ser ve d. 6 0 2 - 1 4 8 8 6 - 0 1 , Rev. A
2 .9 1 + 1 Prot e ction
The Event HD support s 1+ 1 protect ion as an option for a critical link. I n t his
configuration, protect ion is prov ided in a single 1 RU chassis. The SDI DUTM contains t wo
power supplies and two m odem s. The power supply, ODU, I F/ t elemetry and m odem are
protect ed. The digit al framing and LI Us are not . One m odem is referred t o as the west
m odem and t he other as t he east m odem . 1+ 1 protect ion can be run in two m odes called
Protect ed Non-Diversity and Protected Diversity.
2 .9 .1 Pr ot e cted N on- Dive r sity ( H ot Standby)
Figure 2-9 shows operation in Protect ed Non-Diversity m ode, also called Hot Standby. I n
this m ode, one ODU at each location t ransm its t o two ODUs at t he ot her location. This
m ode does not require t he ext ra bandwidt h or interference protect ion. I t provides hitless
receive switching and hot st andby. The SDI DU
TM
aut om at ically switches t ransm it ODU
upon appropriate ODU alarm or ODU int erface error, m inim izing t ransm it outage t im e.
w
Figure 2 - 9 . 1 + 1 Prot ect ion in N on- Diversit y M ode
2 .9 .2 Prot ect e d Dive r sity
I n Protect ed Diversity m ode, t he link between each pair of m odem s is t he sam e, as
shown in Figure 2- 10, providing complet e redundancy. This arrangem ent requires
bandwidth for bot h links and non- int erference between t he links, but it provides hitless
receive and t ransm it swit ching. The SDI DU
TM
supports bot h frequency and spat ial
diversity.