Digital radio teknologi

Systemcom A/S
jon.otterskred@nordialog.no
+47 900 20 366

Introduction
MOTOTRBO System
MOTOTRBO Professional Digital Two-way Radio System is a digital
communications platform that combines the best of two-way radios
with digital technology.

MOTOTRBO™ Technical Training
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MOTOTRBO Digital Radio Technology

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Overview
Inputs:
Voice or
IP data

MOTOTRBO Digital Processes

1

2

3

Output:
2-slot TDMA

4

The technologies that enable MOTOTRBO to deliver benefits like greater usable range, integrated
voice and data, spectrum efficiency, and increased battery life will be explored on the next 4 slides:
1: Analog to Digital Conversion
2: Vocoding and Forward Error Correction
3. Framing
4. TDMA Transmission
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Overview: Step 1 - Analog to Digital Conversion
Analogous to how a written message is converted to a data stream by a fax machine, Analog
to Digital Conversion translates the user’s voice (microphone input) to a digital bitstream.

1

The digital bitstream contains a LOT of bits - far too many to transmit over a radio channel.
So some form of compression is required…..
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Overview: Step 2 - Vocoding & Forward Error Correction
Vocoding (Voice encoding) compresses speech by breaking it into its most important parts and encoding
them with a small number of bits. Because it focuses on human speech, it greatly reduces background noise.

2

Forward Error Correction (FEC) enables the receiving radio to correct bit errors that occur due to RF
channel impairments - enabling more consistent audio performance throughout the coverage area.
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Overview: Step 3 - Framing
Framing organizes digital voice (or data) into digital packets: the voice or data becomes payload (like a letter
in an envelope) while the header describes the type of call, source and destination address, etc. (like the
addressing information on the envelope). This enables one radio to provide integrated voice and data.

3

Compressed
digital voice
Or
IP Data

14

Digital Packets

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Overview: Step 4 - TDMA Transmission
Transmission encoding completes the encoding process (like adding the machine-readable sorting
information on the envelope) and finally “mails the letter.”
TDMA (Time Division Multiple Access) organizes a channel into 2 time slots: a given radio’s transmitter is
active only for short bursts, which provides longer battery life. And by transmitting only on their alternating
time slots, two calls can share the same channel at the same time, thereby doubling spectrum efficiency.….

4

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Spectrum Efficiency
Today’s Analog

MOTOTRBOTM
Slot 2
Slot 1
Slot 2

Regulatory
emissions
mask

Slot 1

e
tim

Slot 2
Slot 1

frequency
frequency

12.5kHz
Channel

12.5kHz Analog
• 1 voice for each 12.5kHz channel
• 1 repeater for each channel

16

12.5kHz
Channel

12.5kHz TDMA
• Divides existing channel into two timeslots
• Delivers twice the capacity through repeater
• Performance is same or better than 12.5kHz FDMA
• 1 repeater does work of 2
• Reduces need for combining equipment
• Enables 40% increase in radio battery life

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2 Slot TDMA
1. Radio gives priority to voice
(e.g.: if its time for radio to
send in its GPS update and
the user happens to press
PTT, the data will wait).

Voice Call 1
(or Data)

2. Radio cannot transmit and
receive at the same time.
timeslot 1

timeslot 2

timeslot 1

timeslot 2

Voice Call 2
(or Data)

timeslot 1

timeslot 2

3. Radio transmits in only one slot
at a time (e.g.: radio cannot
transmit voice on slot one
while also transmitting data on
slot two).
4. Calls are not dynamically
allocated to slots, they are
statically assigned to a
frequency and slot in CPS.

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Reduces Infrastructure Equipment
Analog 2-Channel System

MOTOTRBO 2-Channel System

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Digital Audio Coverage

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Digital Audio Coverage (Cont.)
• What end user will experience with Digital Audio:
- Consistent performance throughout coverage area with no gradual fade at
the fringes.
- Digital sounds different.
- Background noise reduction.

• What end user will NOT experience with Digital Audio:
- Digital radio ‘CD quality’.
- Digital cannot solve historic problems.

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System Coverage Planning
Coverage Considerations
Before coverage (usable
audio range) can be
defined.
Identify the minimum
acceptable audio quality.

One accepted method is
known as Delivered
Audio Quality (DAQ).

• DAQ measures the intelligibility and quality of voice conveyed through a
communications system.
• Audio quality is measured on a 5-point scale, with the DAQ rating of 3 as the
minimal acceptable audio quality level for public safety applications.
• The definition of DAQ 3 is: ‘Speech understandable with slight effort. Occasional
repetition required due to Noise/Distortion’.
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System Coverage Planning (Cont.)
Coverage Considerations –
Greater Usable Range

• The figure illustrates the regions of
coverage that have comparable audio
quality for a MOTOTRBO site compared
to an equivalent analog site.
• For a DAQ 3, which is the minimum
acceptable audio quality level for public
safety applications, MOTOTRBO
provides a greater useable range than
analog when all other factors are
considered equal (e.g. transmit power
level, antenna height, terrain, etc.)
• In general, plan as you would for an
analog system at the same power level
and enjoy the better performance.

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Frequency Licensing
• The licensing process varies from region to region.
• Emission Designators: Includes several pieces of vital information, such as
modulation, signal, type of information and size of the channel.
• This determines the channel width your system will occupy. For MOTOTRBO
systems, the Emissions Designators are
– Data only: 7K60FXD
– Voice and Data: 7K60FXE
• If you have a 12.5kHz license, you will need to update your emissions designator.
• If you have a 25kHz license, you will need to update your emissions designator.
You will generally not be allowed to break it into two – 12.5kHz channels.
• For regulators who currently assign CTCSS/DCS tones to analogue PMR channel
licenses, for MOTOTRBO they will need to assign Color Codes instead.
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MOTOTRBO Digital Features

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Digital Voice Features - Group Call
• Digital Group Call is a way of enabling
groups to share a channel without
distracting and disrupting other radio users.

Channel = Frequency 1
Time slot = 1
Group List: TG_1
Rx Group List contains = TG_1

• Both transmitting and receiving radios must
be on the same logical channel (frequency
and timeslot).
• Two radio users cannot listen to each other
if they are on the same logical channel
(frequency and timeslot) but different
groups.
Tr

s
an

it
m

Transmitting Radio
Radio ID = 002
Radio Alias = Bill

25

• Group Call considerations:
– Which members of a functional workgroup
need to communicate with each other?
– How workgroups interact with members of
other workgroups.
– How users can collectively share the channel
resources.

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Digital Voice Features - Private Call
Time slot = 1

Note: “Private Call” is also
known as “Individual Call”.

• Private Call allows one-to-one
communication between transmitting and
receiving radio.
• Private Call does NOT imply encryption or
any other level of security above and
beyond the inherent level of digital privacy.

Target Radio
Radio ID = 001
Radio Alias = Tim

Tr

s
an

it
m

Transmitting Radio
Radio ID = 002
Radio Alias = Bill

26

• An employee could for example use a
Private Call to privately alert a specific
manager about a security incident, rather
than placing a Group Call that would be
heard by a whole group.

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Digital Voice Features - All Call
Time slot = 1
All Call ID (reserved) = 16777215

• All Call is a one way voice communication
between a privileged radio with other radio
users within the same logical channel.
• The transmitting radio uses a special All
Call group that enables every radio user
within the same logical channel,
(regardless of Group) to receive the
communication.

Tr

s
an

it
m

Transmitting Radio
Radio ID = 002
Radio Alias = Bill

27

• This feature is particularly useful when a
supervisor needs to communicate to all
radios within the same logical channel
(frequency and timeslot) rather than
individual groups or users.

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Embedded Digital Signaling

• In the framing process, vocoded speech is formatted for transmission.
• This process includes organizing the voice and any embedded signaling information.
• Information such as call type (private, group or all system) as well as identification
information and/or control information, is used to notify listeners on a voice call system
events and status.
• ‘Late entry’ allows a user to join a voice transmission that is already in progress. The
system allows for this to happen because the digital signaling information is repeated
periodically during the course of the call.
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Embedded Digital Signaling – PTT ID and Aliasing
• Alias - When programmed via the CPS or front panel, a user friendly
alphanumeric ‘name’ will be displayed.
• PTT ID - Allows target radio to identify the originator of a call.
Illustration on the left shows Group Call Alias for
transmitting and receiving radio.

Illustration on the right shows Private Call Alias for
transmitting and receiving radio.

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Digital Signaling Features

• Digital Signaling features send special messaging packets over the network. Radio
Disable, Remote Monitor, Radio Check, Call Alert and Digital Emergency are types
of Digital Signaling features.
• An Acknowledging Message is received by the Initiating Radio (Acknowledging
Messages are received by the Initiating Radio for all Digital Signaling Features).
NOTE: DP 3400 and DM 3400 radios do not support all of these features because they don’t have keypad/display for menu functionality.

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Digital Signaling Features – Radio Disable
• This feature typically allows a
supervisor radio to disable another
radio via over the air signaling.

Supervisor Radio

Ra
di
o

Note: A supervisor radio
simply refers to a radio
which has been configured
with privileged features.
Di
sa
bl
e

• The disabled radio displays blank
screen and is unable to make or receive
calls.
• Once disabled, the radio can only be
enabled via CPS or by a Radio
Uninhibit command from another
supervisor radio.
• This feature can be used to stop any
inappropriate use of radio, or to stop
stolen radio from functioning.

Target Radio

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Digital Signaling Features – Remote Monitor
• This feature typically allows a remote
user to activate a target radios
microphone and transmitter for a period
of time.
• A call is silently setup on the target
radio, and its PTT is controlled remotely
without any indications given to the end
user.

Supervisor Radio

Re
m
ot

e

M

on

ito

• This feature is used to ascertain the
situation of a target radio which is
powered-on, but is unresponsive.

r

Target Radio

32

• Situations such as theft, incapacity of
the radio user or allowing the initiator of
an emergency call to communicate
hands-free in an emergency.

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Digital Signaling Features – Radio Check
• This feature allows the initiating radio to check if a
target radio is active within the system without
notifying the user.
• Besides Busy LED, there is no visible or audible
indication on the target radio.
• The target radio automatically and silently responds
with an acknowledgement to the initiating radio.

Supervisor Radio

Ra
di
o

• If a radio user is non-responsive, Radio Check
could be used to determine if the target radio is
switched on and monitoring the channel.

Ch
ec
k

Target Radio

33

• If the target radio responds with an
acknowledgement, the initiator could then take
additional action such as using the Remote Monitor
command to activate the target radio’s PTT.

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Digital Signaling Features – Call Alert
• This feature allows the initiating radio to
essentially page another radio user.
• When a radio receives a Call Alert, a
persistent audible and visual alert is
presented to the target radio. The initiator
of the Call Alert is also present.
• If the target user presses the PTT when a
Call Alert screen is active, it starts a
Private Call to the initiator of the Call Alert.

Initiating Radio

Ca
ll

Al
er
t

Target Radio

34

• For in-vehicle applications, this can be
used in conjunction with the Horn and
Lights option. When a user is away from
his vehicle, a Call Alert can initiate the
vehicle’s horn and lights to sound and
flash, which notifies the user to return to
the vehicle and call the originator.

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Digital Signaling Features – Digital Emergency
• MOTOTRBO radio allows a radio user in
distress to send out an emergency alarm
message and emergency voice to a group.
• The emergency alarm message is
acknowledged by a single (supervisory)
radio present within the system.
Initiating Radio

Di
gi

• The emergency alarm message contains the
individual radio ID of the initiator.
ta
lE
m
er

• Revert channels can be specified for
emergencies.

ge
nc
y

Supervisor
Radio

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Digital Signaling Features – Digital Emergency (Cont.)
• Three alarm modes configurable via the
CPS are:
- Emergency Alarm Only
- Emergency Alarm and Call
- Emergency Alarm with Voice to Follow

• Four alarm types configurable via the
CPS are:

Initiating Radio

Di
gi

ta
lE
m
er

-

ge
nc
y

Supervisor
Radio

36

Disabled
Regular
Silent
Silent with Voice

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Multiple Groups and Channel Scan
• MOTOTRBO supports
– Multiple Groups: monitors a list of different groups on a given channel/slot
– Channel Scan: monitors a list of different channels within a system

• Channel Scan supports scanning of
– analog voice
– digital voice
– digital signaling

• Multiple Groups and Channel Scan support both repeater and direct radio
channels

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Multiple Groups
• The radio unmutes only when a relevant group is transmitting on the
channel.
• The relevant groups for a given channel (group members) are defined by
the Receive (Rx) Group List associated with that channel.
• One Receive (Rx) Group List can contain a maximum of 16 group
members and a maximum of 50 Receive (Rx) Group Lists can be defined.
• For repeater channels, the group call hangtime is defined by a repeater
timer and for direct radio channels, the group call hangtime is defined by a
radio timer.
• The radio is allowed to talkback to the group for the duration specified by
the group call hangtime.
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Channel Scan
• In scan mode the radio continually searches a list of channels for activity
of interest.
• The relevant channels to be scanned (scan members) for a given channel
are defined by the Scan List associated with that channel.
• One Scan List can contain a maximum of 16 “Scan Members” and a
maximum of 32 Scan Lists can be defined.
• While a radio is scanning it is looking for transmissions (voice or signaling)
addressed to itself using
• One of the group addresses in the Scan List associated with the channel it is
scanning at that moment
• It’s individual address (e.g. Private Call) or
• The “All Call” address

• A mixture of digital and analogue channels may be included in a Scan List.
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Channel Scan (Cont.)
•

If activity of interest is found, the radio stops and switches to that channel.
The radio then remains on that channel until the activity of interest has
ceased for a period of time defined by the radio “Scan Hang Timer” (or until
a higher priority call is detected).

•

Channel Scan limitations
– Since Channel Scan requires the radio to switch between channels, there is a
possibility that the radio will miss a transmission.
– The larger the Channel Scan list, the greater the possibility that a transmission
will be missed.
– The Channel Scan list should be configured to be as short as possible.
– A scanning radio will eventually detect group and “all call” transmissions via
“late entry”, however most individually addressed transmissions (e.g. Private
Call) will need to be prefixed with “Transmit (Tx) Preamble” if they are to be
detected by a scanning radio.
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Channel Scan – Priority Levels
• Priority levels can be configured for members of a Scan List. Three levels
of priority are:
- Priority-1
- Priority-2
- Non-Priority

• At present, Priority Scan is not available for:
- mixed analog-digital scan lists, or
- digital-only scan lists containing any repeater channels.

• Priority Scan is only available for analog-only Scan Lists and digital-only
Scan Lists containing only direct mode channels.
• Priority levels are configurable via CPS.

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Channel Scan – Priority Levels (Cont.)
• If the following type of activity of interest is found while the radio is
scanning:
- data addressed to the scanning radio
- an individual call (Private Call)
- Priority-1 scan member

the radio stops scanning and switches to that channel for the duration of
the call.
• If however the activity of interest is a voice group call on a Priority-2 or a
Non-Priority scan member, the radio continues to periodically scan any
higher priority scan members defined.

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Channel Scan – Channel Marking
• Although relatively short, its does take time to determine if a transmission
is of interest on a higher priority scan member. During this time, there is an
audio hole on the current scan member.
• Channel marking offers a way to mitigate the duration of the audio hole.
• It introduces a logic that assumes that if a transmission was identified as
not of interest, there is no need to fully review it at every scan interval.
• The feature greatly increases audio quality while a radio is in priority
sampling mode.

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MOTOTRBO Analog Features

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Introduction
• To facilitate a smooth “digital” migration from legacy “analog”
systems, MOTOTRBO also supports “analog” operation.
• MOTOTRBO portable and mobile radios are able to switch
between “analog” and “digital” operation either via user selection
(i.e. channel selector) or automatically (i.e. dual mode scan).
• MOTOTRBO repeater is configured either for analog or digital
operation.
• In analog mode, MOTOTRBO portable and mobile radios are
able to operate in either repeater or direct/talkaround mode.
• In analog mode, MOTOTRBO utilizes traditional FM technology
(both 12.5 and 25kHz channel bandwidth supported).
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Voice Features
Feature Name

Description

Time-Out Timer

Sets the amount of time that the radio can continuously transmit before the
transmission is automatically terminated.

Squelch

Special electronic circuitry added to the receiver of a radio which reduces
or squelches, unwanted signals before they are heard through the speaker.

Admit Criteria

Enables a radio to refrain from transmitting on a channel which is already in
use.

Monitor/Permanent
Monitor

The user can check channel activity by pressing the monitor button. If the
channel is clear, the user hears static. If the channel is in use, the user
hears the conversation. It also serves as a way to check the volume level of
the radio, as while pressing the monitor button, the user can adjust the
volume of the static/conversation heard.

Priority/Dual Priority
Scan

Priority Scan allows a user to program the radio to scan more frequently
transmissions on the most important channel, and ensure they do not miss
critical calls. Dual Priority Scan allows a user to program a radio to
frequently scan transmissions on the two most important channels, and
ensure they do not miss critical calls.

Talkback Scan with
Home Channel Revert

Talkback Scan allows activity on different communications channels to be
monitored and answered. Home Channel Revert allows a user to
automatically access a preferred channel.

Talkaround

Allows a user to talk directly to another unit for easy local unit-to-unit
communications and bypass the repeater.

Nuisance Channel
Delete

Allows a user to remove a channel with unwanted activity (i.e. a Nuisance
Channel) from the scan list temporarily.

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Additional Features

• In analog mode, MOTOTRBO supports a limited MDC signaling
feature set (i.e. Emergency Signaling, PTT-ID and Call Alert).
• Additionally, a 3rd-party 5-tone option board is expected for
MOTOTRBO Q4 2007.

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MOTOTRBO Integrated Data

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Overview of Data Services
MOTOTRBO supports data services in digital mode only:
•

Built-in data modem
–
–
–
–

•

Text Messaging
–
–
–

•

Standard UDP/IP – compatibility with IP applications
Internet Protocol (IPv4) addressing
Approx 2kbps protected data throughput per slot
Future enhancement - double throughput with dual-slot data

Direct radio-to-radio or via 3rd party application (future availability)
Free-form (up to 140 characters)
Pre-programmed messages entered via CPS (up to 30 messages)

Location Tracking
–
–

GPS equipped portables and mobiles available with built-in GPS receivers.
Using the integrated data services, GPS equipped portables and mobiles
are able to transmit their location coordinates over the radio system, to a
3rd party application.

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Overview of Data Services (Cont.)
•

Telemetry
–

–

Basic built-in telemetry functionality allows the radio to translate the receipt
of a telemetry message to GPIO (General Purpose Input/Output) action,
and to translate GPIO action to a transmitted text message.
Ability to configure radios as telemetry transponders. Telemetry commands
can be sent from the radio. The radios may be used to automatically send
information to the control and receive status of another device, and to send
messages to report the status of local devices. A user can enter a number
of text strings and assign an action and a destination address to each
string.

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Accessory and Peripherals
• The MOTOTRBO Radios support an improved accessory and
peripherals interface. This new interface is Motorola’s platform for
the future accessory development and it is not backwards
compatible with older accessories.
• It supports the following capabilities:
-

Enhanced Audio Functionality
USB Capability
Core peripherals
RF Input/Output
Rugged and Submersible

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Application Partner Program
• The MOTOTRBO system is complete and robust enough to fulfill the
diverse needs faced by a variety of customers.
• The Application Partner Program enables third party developers to create
customized applications that add value to customers in different vertical
applications.
• Motorola provides support to third party developers who are members of
the Application Partner Program.

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Application Partner Program – Application Development Kits

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System Topologies

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System Topologies
Direct Mode

Freq 1
Digital Channel

Freq 1

MOTOTRBO Radio
MOTOTRBO Radio

MOTOTRBO Radios in Digital Direct Mode

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System Topologies
Direct Mode - Analog Interoperability

Freq 2 (or Freq 1)

Freq 1
Analog Channel

Digital Channel
Freq 2 (or Freq 1)

Freq 1

Legacy Analog Radio
(or MOTOTRBO Radio
Analog mode)

MOTOTRBO Radio
Digital mode
MOTOTRBO Radio
Analog & Digital mode

User selects either analog or digital
direct mode

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System Topologies
Repeater Mode

Fre
q1
Dig

ital

Fre
q2

eq
Fr

Slo
t1

1
ot
Sl
2

tal
igi
D

Ch
ann
el

l
ne
an
Ch

eq
Fr

Slo
t1

1
ot
Sl
1

MOTOTRBO Radio
Digital mode

MOTOTRBO Radio
Digital mode

Fre

q

Dig

lot
1S
ital

Fre
q2

2

MOTOTRBO Repeater
2-slot operation

el
ann
Ch

Fre

q

lot
2S

2

Dig
ita
l
Fre
q1

Slo
t2

Ch
an
ne
l

Slo
t2

MOTOTRBO Radios in Digital Repeater Mode
MOTOTRBO Radio
Digital mode

57

MOTOTRBO Radio
Digital mode

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System Topologies
Repeater Mode - Analog Interoperability
Freq 2

4(

o

tal
igi
D

l
ne
an
Ch

e
Fr

An

Fre
q1
alo
g

Fre
q2

Ch
an
ne
l

Fre
q4

MOTOTRBO Repeater
2-slot operation

Dig
ita
l
Fre
q3

An

Legacy Analog Repeater
(or MOTOTRBO Repeater
Analog mode)

User selects between Digital Repeater mode or
Analog Direct / Analog Repeater mode

58

(
q3

Fre
q1

(o r

Fre
q2
Ch
)S
an
lot
ne
1
l

(or

Fre
q2
alo
g

or

t1
Slo
1)
eq
Fr

Fre
q

1)
Slo
t

MOTOTRBO Radio

Freq 4 (or F
req 2)

eq
Fr

Digital Chan
nel

Freq 2
Legacy Analog Radio
(or MOTOTRBO Radio
Analog mode)

2
eq
Fr
r

1
ot
Sl
)

Freq 4 (or F
req 2)

Analog Channel

1

Ch
an
ne
l

MOTOTRBO Radio

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System Topologies
Analog to Digital Migration
• System Migration is the process of moving from one operating
platform to another (i.e.: from an analog two-way radio platform to
a digital two-way radio platform).
• Select the migration strategy based on your customer’s needs.
New / Full
System
Replacement

59

Migration
Preparation

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System Topologies
Analog to Digital Migration
Strategy

Description

New / Full System
Replacement

Deploy all new MOTOTRBO equipment and operate in
digital mode only.

Migration

Transition the customer’s system from analog to digital
site by site / channel by channel / talkgroup by talkgroup.
Deploy MOTOTRBO equipment for selected sites /
channels / talkgroups and operate the system in analog
and digital mode by leveraging the radio’s capability to
scan and support both modes.

Preparation

Deploy new digital capable MOTOTRBO subscriber units
but still operate in analog (legacy) mode. Switch to digital
capability when entire fleet is MOTOTRBOTM.

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System Capacity Planning

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Definition

The System Capacity is the nominal
loading that occurs on a channel that
will still result in an acceptable level of
performance and user experience.

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Capacity Considerations
Text Messaging
Traffic

Location Tracking
Traffic

Voice
Traffic

This information determines the decision on the following:
• How many frequencies are required?
• How many channels are required?
• How will the talkgroups be distributed across the channels?
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Capacity Considerations - Standard Voice and Data Traffic Profiles

Calls per user per hour is an aggregate of all units and groups sharing
the channel
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Capacity Considerations - Loading Analysis Results

The y-axis is an approximation of how likely a customer is to encounter a busy channel given the assumptions
described in the previous slide. It's not a specification or guarantee of performance, and each customer's experience
will vary.
If there is Low Voice Only traffic, the solid pink line should be the line of reference. Based on the solid pink line, for 30
users per slot, there is good probability that a given user will find the channel to be available. In the “fair” regions of
the chart, a user is progressively more likely to encounter a busy channel.

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Capacity Considerations - Options to Optimize Capacity
•

Distribute high usage users and talkgroups between slots of the
repeater(s).
– Keep the number of high usage users per channel to a minimum.

•

Data applications retry attempts and intervals (configure at server).
– Decrease retry attempts.
– Increase retry intervals.

•

Optimize outbound message rate of data applications (configure at
server).
– Pace outgoing messages appropriately to avoid congesting the channel.
– A MOTOTRBO radio can only buffer up to 10 messages.

•

Minimize location periodic update rate.
–
–
–
–

Lengthen the location update interval.
Only use a high update rate for selected users or in an emergency.
Minimum update rate is 5 seconds. Maximum update rate is infinite.
It is recommended that the periodic update rate should be longer than 2 minutes.

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Systemcom A/S
+47 900 20 366

Capacity Considerations – Options to Optimize Capacity

If a channel has 10 users, and the users have High Voice Usage, then it is recommended that the Location Update
Period be set to 3.5 minutes or higher (longer).

67

Digital radio teknologi

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