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SmarTrunk Xpress Digital trunking systems are directed to the private
carrier/customer licensee who is considering converting conventional
VHF/UHF repeaters to trunked operation. Perhaps you are an operator of
shared community repeaters who would like to achieve higher customer
loading (and greater profits) from your existing system. Or perhaps you
operate a private on-site system (example: Shop watch Schemes, Community
broadcast repeaters) of two or more VHF or UHF conventional
channels used for plant security or maintenance. Either way, converting
your conventional channels to trunked operation will significantly
increase your system capacity while providing privacy, system security,
and advanced features such as selective and emergency calling.
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Nabishi Single Channel Smartrunk Repeater |
 Nabishi 4-channel Trunking Site Equipment |
 Nabishi 4-channel Trunking Site Equipment (Rear) |
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What is SmarTrunk?
The term "trunking" originated decades ago in the telephone industry
to describe the process of selecting one clear communications path from
many possibilities. It is based on the premise that if 100 users are
sharing a certain communications network, only 10 users will actually
use the network at any one time. Therefore, it is not necessary to
install 100 trunk lines to serve 100 telephone customers; only 10 lines
will be sufficient to provide a high level of service.
The Trunking Advantage
¨ Efficiency
¨ Privacy
¨ Selective Calling
The primary advantages of any trunked radio system can be summarized
as follows:
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Automatic selection of a clear channel:
In a conventional radio system, the user may only have access to a
single channel. If the user wishes to make a call, he must first
monitor the channel to make sure it's clear. If the channel is busy,
the user must continue to monitor the channel until the co-channel
user has terminated the conversation. By contrast, in a trunked system
the channel selection is automatic. When the user initiates a call,
the trunking system electronically "monitors" each channel and selects
one clear (unused) channel from many possible channels.
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Channel Privacy:
In a conventional system, other co-channel users can easily eavesdrop
on conversations. In a trunked system, other system users can not
listen in on other conversations. A radio can only join a conversation
when directed by the trunking controller.
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Channel Exclusivity:
In a conventional system, discourteous co-channel users can "jump" on
a channel in the middle of another conversation, thereby interrupting
the call in progress. In a trunked system, once a channel is selected,
it becomes exclusive for the duration of the transmission. Other users
cannot interrupt or interfere with the call.
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Selective Calling:
In most conventional radio systems, selective calling is an expensive
add-on option or may not be available at all. On the other hand, some
trunked radio systems provide extensive selective calling capabilities
as a standard feature. This means that users can selectively call
different groups or individuals in the system. Each user is typically
assigned a unique individual ID code and one or more group ID codes.
These codes can be dialled by other users in the system to select only
the specific groups or individuals with whom they wish to communicate.
An example, if you operate two community repeaters and each channel is
busy 20% of the time, there is a 20% chance that the channel assigned
to a given customer will be busy when one of his mobile groups wishes
to make a call. But, if the two channels are trunked together, the
trunking system will select an open channel when a mobile group wants
to make a call.
The odds that both channels are busy at the same time is only 4%. This
means that:
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Your existing customers will receive a much higher level of
service; or,
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You can add 2.5 times as many customers on the system with the
same level of service.
 Impact of Trunking Conventional Channels
Applications
- Small police and fire departments
- Shop watch Schemes
- CBS - Community Broadcast systems
- Government agencies
- Public telephone systems
- Mining operations
- Large industrial manufacturing facilities
- Oil & gas pipeline operations
- Colleges or university campuses
- Petro chemical operations/oil refineries
- Airports
- Forestry and fishing fleets
- Shopping Centres and Hotels
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