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Bosch Security Systems | 2011-02
2011-02 | Installation and User Instructions | 2 | Introduction en | 78
3Calls
3.1 Introduction
As Praesideo is a public address and emergency sound
system, it is used to distribute background music, live
speech and evacuation messages. All audio in the
system is distributed in the form of calls.
3.2 Call attributes
3.2.1 Introduction
A call always consists of the following attributes:
• Priority (see section 3.2.2)
• Call content (see section 3.2.3)
• Routing (see section 3.2.4)
• Timing (see section 3.2.5)
3.2.2 Priority
To each call, a priority is assigned. When two or more
calls are addressed to the same zone or need shared
resources (e.g. the message player), the system only
starts the call with the highest priority. The range of
priorities that is available for a call depends on the type
of call (see table 3.1).
Calls with the same priority operate on first come first
serve basis, except in the case of priority 255: calls with
the same priority 255 overrule each other, so the latest
becomes active. This assures that high priority
microphones that are left behind in an active state will
never block the system.
3.2.3 Call content
The content of a BGM call typically consists of an audio
signal coming from a BGM source, such as a CD player
or a tuner. The content of normal calls and emergency
calls is defined by a call macro, which can consist of:
• A start chime
• Prerecorded message(s)
•Live speech
• An end chime
3.2.4 Routing
The routing of the call is the set of zones to which the
call is intended to be addressed. Whether the call
actually is addressed to the selected zones depends on
the priority of the call (see section 3.2.2) and its routing
scheme.
Each call can have one of the following routing
schemes:
•Partial
• Non-partial
•Stacked
By definition, partial calls do not require the entire
routing to be available at the start of the call and during
the call. When a partial call is started and a part of the
routing is not available, the call is only distributed to the
available part of the routing. When a part of the routing
becomes unavailable during the call, the call continues
in the parts of the routing that are still available.
Non-partial calls are calls that require the entire routing
to be available at the start of the call and during the call.
When during the call a part of the routing becomes
unavailable, the call is aborted.
Stacked calls are calls that have been recorded for later
playback. This feature is only available in combination
with a call stacker (see chapter 23).
table 3.1: Priorities and call types
Priority Call type
0 to 31 BGM calls
32 to 223 Normal calls
224 to 255 Emergency calls
Note
Non-partial normal calls can only be started
when the entire routing is available. BGM and
emergency calls can be started when the entire
routing is not available.
Note
BGM calls and emergency calls without live
speech are started in the non available parts of
the routing as soon as these parts are released.