20 System Feature Overview
April 2011 68007024085
Greater detail on system services available in direct-mode and repeater-based system
topologies is described in “System Components and Topologies” on page 137.
2.2.2 MOTOTRBO Supports Analog and Digital Operation
The MOTOTRBO system can be configured to operate in analog mode, digital mode, or in
Dynamic Mixed Mode. The system can consist of multiple repeaters. A single MOTOTRBO
repeater configured to operate in Dynamic Mixed Mode can dynamically switch between analog
and digital modes depending on the type of call it receives. A repeater in Dynamic Mixed Mode
system cannot be part of multiple repeater system in which the repeaters are connected over the
network for IP Site Connect or Capacity Plus operation.
MOTOTRBO portable and mobile radios can communicate in analog and digital. The mobile or
portable radio user selects the mode of operation (analog or digital), and physical and logical
channel using his channel selector knob (each channel selection position is configured for a
particular call type on either a digital channel that specifies both frequency and time slot, or an
analog channel that specifies both frequency and 25 kHz or 12.5 kHz bandwidth). Radio channels
are either analog or digital. This is configured by the CPS. The radio can scan between analog and
digital channels.
Greater detail on channel planning and configuration is provided in “System Design
Considerations” on page 203.
2.2.3 MOTOTRBO Channel Access
Channel access dictates what conditions a radio is allowed to initiate a transmission on a channel.
The channel access rules of MOTOTRBO are governed by the mobile and portable radios. It is the
radio’s responsibility to assess the state of the system, and utilize its channel access rules to
decide whether to grant the call to the user.
In repeater systems, it is the repeater’s responsibility to:
• Identify if a channel is busy, or
• Identify if a channel is idle, or
• Inform for which radio the channel is reserved.
The repeater does not block or deny any channel access from radios on its system, but will not
repeat transmissions from another system.
There are two main types of channel access in a MOTOTRBO system: Polite and Impolite access.
In the configuration software, channel access is referred to as the Admit Criteria. MOTOTRBO
supports the following Admit Criteria:
• Always: This criteria is often referred to as “Impolite” channel access, and can be
applied to analog and digital channels.
• Channel Free: This criteria is often referred to as “Polite to All”, and can be applied to
analog and digital channels
• Color Code Free: This criteria is sometimes referred to as “Polite to Own Color Code”
or “Polite to Own System”, and is applied only to digital channels.
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