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CONVENTIONALVS
TRUNKED SYSTEM
Two-Way Radio Overview
Conventional Systems
Trunking Systems :
- Single Site
- Multi-Site Systems
2-Way Conventional
Distance = ?
PTT
Portable A Portable BPortable A Portable BTalk Listen
Listen TalkTalk Talk
Receive
Send
When Distance Increase !
5 - 7 kmsPortable A Portable B
Out of Range !!!
Repeater
Distance = 30 - 40 kmPortable A Portable B
ReceiveSend
PTT
Use Repeater
(High Point)
F1
Repeater
When No.of Users Grows .....
F1
F1
F1F1
F1
Control Station for Dispatcher
Congestion !!!
Increase Channels Increase Repeaters
Repeaters
F1 F2 F3 F4
F1
F4
F3
F2
Control Station for Despatcher
Conventional SystemConventional System
Ch.A Ch.B Ch.C Ch.D
Problem ! Required more Frequencies
No privacy of communication
Inefficient of Spectrum
Utilization
Solution is Trunking !!!
What is Trunking ?
Mutual Sharing of Channel Number Communication Among a Large Group of Users
Trunked SystemTrunked System
Ch.A Ch.B Ch.C Ch.D
C O N T R O L L E R
INDIVIDUAL CALL
GROUP CALL
Trunking Architecture
N CH. RBS
PSTN PABX
SWITCHING
Conventional Three Independent Channels
2
USER GROUP D USER GROUP F
AVAILABLE
1
USER GROUP A USER GROUP B
USER GROUP C
3
USER GROUP G USER GROUP H
USER GROUP I
IN USEIN USE
Blocked
Idle Users !!
2
USER GROUP D USER GROUP F
1
USER GROUP A USER GROUP B
USER GROUP C
3
USER GROUP G USER GROUP H
USER GROUP I
Controller
Trunked Three Shared Channels
idle channel allocated
Trunked Radio System
RepeatersF1 F2 F3 F4
TG8
TG1
Central Controller
TG3
TG6
TG2
TG4
TG5
TG7
Note : User Groups are no longer tied to Frequency ! Each User Group is affiliated to Talk group ID
F1
Repeater
As User Organization Grows !
Single Site
Coverage Area
•No.of Users Increase•Users Travel beyond Single Site Coverage Area
Why Wide Area Systems ?
In-building Coverage improvement Improve Coverage Reliability
Conventional Multi-Sites
Repeater
Receiver Voting System
Repeater
Wide Area Coverage Using Receiver Voting System
Rx Audio Rx Audio
Tx Audio Tx Audio
Trunking Multi-Sites
RepeaterRepeater
Wide Area Coverage Using Zone Controller
Audio Switch
Wide Area Zone Controller
F1 F2 F3 F4F1 F2 F3 F4
TG1
TG3 TG6
TG2
TG4 TG5
Require a lot more supporting equipments than shown
Main Differences
Conventional Trunking
Users in a group have a dedicated channel
All users on that channel hear each other
Users must wait for clear channel
When no users are talking, channel is idle.
Over 24 hour period, most channels are idle
Users are in a dedicated “talk group”
Channels are pooled into a system
supports many talk groups per channel
When a user in a talk group speaks, the system assigns an idle channel to the group
“Talk groups” can be prioritized
Conventional mode only Conventional & Trunking Mode
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