HONEYWELL Aerospace Electronic Systems Page 43
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Logic units can be used to specify OOOI conditions. OOOI logic can be as simple or as complex as the
user requires. Figure 27 depicts a portion of an example logic unit for OOOI events.
Figure 27 OOOI Logic Unit
4.2.6 Preferred Channel Management
Honeywell first introduced the concept to the industry of automated frequency management based on
aircraft position. This is in contrast to the brute force approach of performing frequency management by trial
and error based on a table of possible frequencies. This automated approach provides for more flexibility for
a user in terms of selecting service providers while also significantly improves frequency selection, avoiding
problems of long frequency searches (of as much as 25 minutes), ensuring continuos linkage to the
air/ground network. Preferred channel management is a mechanism that allows the user to closely control
which communications medium (VHF, HF, SATCOM) and which VHF frequency (and thus service provider)
to use in a particular region of the world. To facilitate this capability, GBST provides the mechanism to divide
the world into regions. For each region, the user can specify the precedence of the communication channels