14 System Feature Overview
The flat audio response of digital is different from the traditional analog audio response. The
traditional response is a linear response and the louder one speaks, then the louder the received
volume.
Figure 2-7illustrates a traditional analog response in the curves titled Professional Series
and MOTOTRBO with IMPRES RSM (AGC off, Analog). When Analog Mic AGC is disabled, then
the Analog Mic Gain (dB) is adjustable in the CPS General Settings. Therefore, MOTOTRBO in
analog mode is able to deliver the traditional analog response and is adjustable to fit into existing
systems.
Examination of Figure 2-7indicates that digital and traditional analog responses are similar at an
input Sound Pressure Level (SPL) of 98 dB. Below this level, analog is quieter than digital. This is
important to note as a system requiring MOTOTRBO to function as a digital radio and also as an
analog radio during migration, may experience received audio level differences that are mode
dependant. This could occur when scanning both digital and analog channels and the analog
talker is located in a quiet environment such as an office. In quiet environments many users tend
to speak softly and therefore the input will fall below the equivalent response level of 98 dB SPL.
Therefore, during the migration period, the analog response may be quieter than the digital
response.
2.2 Basic System Topologies for Digital and Analog
Operations
MOTOTRBO is a two-way radio system – conventional and trunked. In its most basic form, a
MOTOTRBO system is comprised of radios that communicate with each other in the following
available modes:
• Direct mode
• Repeater mode
• Through a repeater in conventional single site mode
• Through a set of repeaters in IP Site Connect mode
• By trunking a set of repeaters in Capacity Plus mode
• By trunking a set of repeaters connected across multiple sites in Linked Capacity Plus
mode
The MOTOTRBO system can be configured to operate in analog mode, digital mode, or in both
modes.
2.2.1 Repeater and Direct Mode Configurations
In direct mode, receive and transmit functions are both carried out on the same physical channel
(i.e. transmit and receive frequencies are the same).
1.When operating in Analog Direct Mode, MOTOTRBO supports one voice path (transmit
and receive) on one physical channel, and can be configured to operate in 12.5/20/25 kHz
channel bandwidth systems.
The option board interface meets the timing constraint of the MPT1327 standard, which is
a signaling standard for trunked private land mobile radio system. The following features
do not work with MPT1327:
• VOX
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