1. Conventional vs. Trunking Radio Systems
AWIN Network support
Basic level overview

2. Table of Contents
What is Arkansas Wireless Information Network (AWIN)?
Trunking Radio Systems – Basic Overview
Trunking vs. Conventional Radio Systems
How Does Trunking Work?
Trunking Simulcast Technology
Digital vs. Analog Modulation Technology
What is P25?

3. What is AWIN?

4. What is AWIN?
The statewide, multiple site, digital 700/800 MHz trunked communications system using the Association of Public Saftey Communications Officials (APCO) Project 25 (P25) standard.
AWIN provides statewide operations, within the coverage area of the system for public service entities using P25 digital 700/800 MHz radios.
AWIN provides a reliable, statewide means of communication for the state’s first responders. The AWIN system consists of over 100 tower sites and over 27,000 authorized radios.
AWIN is monitored 24/7/365 to ensure that it is available whenever the first responder needs it.

5. Trunking Radio Systems – Basic Overview
Site Controller
Channel 1
Control Channel
Channel 2
Alt. Control Channel
Channel 3
Channel 4
Channel 5
Zone Controller

6. Trunking Radio Systems – Basic Overview What is Trunking?
Trunking is defined as:
“The sharing of a limited number of communication paths (or Trunks) among many users”
Trunking is not a term that is owned or belongs to a specific vendor/manufactorer.
Trunking is not a term that is exclusive to radio systems.

7. Trunking vs. Conventional Radio Systems? ? ? ? ?

8. Trunking vs. Conventional Radio Systems
Conventional Radio (repeater) System:
Uses a dedicated radio frequency for each radio channel in a system (unless sharing a channel)
A Channel = a Frequency (i.e., MHz is County Sheriff, is County Fire)
Each frequency is assigned to a group of users.

9. Trunking vs. Conventional Radio Systems
Conventional Radio (base or repeater) System:
A Channel = A Frequency
If a channel is in use, the radio user must wait in “queue” before being able to transmit on the system.
A new frequency must be obtained each time another “channel” is needed in the radio system.
The system is limited by the number of frequencies in the system.

10. Trunking vs. Conventional Radio Systems
Trunked Radio (repeater) System:
Uses a group of similar radio frequencies to create a “pool” for radio system user to access.
Systems can by built using VHF, UHF, 700, or 800 MHz. (AWIN is 700/800)
A Channel is NOT a Frequency (generally speaking)
A Channel (on your radio) is now a computer generated code…
…referred to as a TALK GROUP

11. Trunking vs. Conventional Radio Systems
Trunked Radio (repeater) System:
The entire system is managed by a computer, on AWIN this is called the Zone Controller. One Zone Controller for the North ½ of the State and one Zone Controller for the South ½ of the State.
All radio in the system, also, are computer controlled, and communicate to the Zone Controller via one frequency know as the “Control Channel”.

12. Trunking vs. Conventional Radio Systems
Trunked Radio System Benefits:
Greatly improved usage of radio frequencies (can be quite scarce depending on frequency band)
Brings radio users together on a common radio system.
Consistency in radio coverage.
Greater over radio system flexibility, including:
Channel (Talk Group) capabilities.
Various user features, including Emergency Alarm, PTT ID, Channel Regrouping, Call Alert, and Radio Inhibit.

13. How Does Trunking Work? Control Channel continuously
Site Controller
Channel 1
Control Channel
RX/TX
Channel 2
Alt. Control Channel
Channel 3
Channel 4
Channel 5
Control Channel continuously
Transmits system data to all radios
Zone Controller

14. How Does Trunking Work? Zone Controller Site Controller Channel 1
Control Channel
RX/TX
Channel 2
Alt. Control Channel
Channel 3
Channel 4
Channel 5
Radio user presses TX button.
The radio information is sent via the control channel
To the site controller
Zone Controller

15. How Does Trunking Work? Zone Controller
Site Controller
Channel 1
Control Channel
RX/TX
Channel 2
Alt. Control Channel
Channel 3
Channel 4
Channel 5
The site controller processes the inbound request and sends the repeater channel command (in this case Channel 3) back to all radios selected on the same Talk Group
Zone Controller

16. How Does Trunking Work? Zone Controller
Site Controller
Channel 1
Control Channel
RX/TX
Channel 2
Alt. Control Channel
Channel 3
Channel 4
Channel 5
The original radio user’s radio automatically switches to
The correct voice channel and begins transmitting; All radios selected on the same Talk Group do the same and hear the voice transmission
Zone Controller

17. How Does Trunking Work? Radio System Fleet Mapping:
Radio “Channels” are now
Called “Talk Groups”.
(Example Law Enforcement
Shown Here)
Radio Zone 1 2
Dispatch 1
TG ID# XXXXXX
TG ALIAS
MAC CALL
Dispatch 2
MAC 1
CID
MAC 2
ADMIN
MAC 3

18. Questions…so far? ?

19. Trunking Simulcast Technology
Simulcast Transmitting
A radio system where the same radio frequencies are Simultaneously Broadcast from all tower sites within the radio system (That are grouped together).
This allows the same radio frequencies to be used throughout the entire coverage area.

20. Trunking Simulcast Technology
Simulcast Benefits
Seamless communications throughout the radio system’s coverage area
Improved radio frequency utilization
Improved coverage in areas with difficult terrain (includes tall buildings)
Improved in-building coverage (signals in overlap zones are “additive”)

21. Trunking Simulcast Technology
Simulcast Cons
The technology can be expensive
Tower site spacing in critical (especially when using NPSPAC frequencies)
Signal “timing” is critical between all sites
Tower site interconnection (via microwave, T1, etc.) is critical and can be expensive

22. Trunking Simulcast Technology
Site 2 f 1 2 3 4 5
Simulcast
Site 5
Site 1 f 1 2 3 4 5 f 1 2 3 4 5
Site 3

23. Trunking Simulcast Technology
Simulcast Issues
Amplitude and frequency of transmitted signals must be very accurately timed to ensure good signal quality.

24. Trunking Simulcast Technology
Simulcast Issues
Slightly out of phase – “Ghosting on a T.V. set
Out-of-phase signals can cause destructive cancellation.
Fully in-phase signals produce constructive composite signals

25. Digital vs. Analog Modulation Technology

26. Digital vs. Analog Modulation Technology
Analog vs. Digital
Digital is the newer format of the two
Newer 700/800 MHz are digital
What is the difference?
Is digital better, and why?

27. Digital vs. Analog Modulation Technology
Analog vs. Digital
Information is sent by changing the frequency, amplitude, or phase of the radio signal.
Analog Transmission
Information is converted to true data bits and applied directly to the radio transmitter using FDMA (or TDMA or CDMA)
Digital Transmission

28. Digital vs. Analog Modulation Technology
Digital Benefits
Clearer audio throughout system coverage area
Improved radio frequency efficiency
Improved system coverage
Imbedded signaling options
Encryption with little-to-no range loss

29. What is P25?
P25
The standard for the manufacturing of interoperable digital 2-way wireless communications products.
Also known as Project 25 or APCO 25.
A user driven standard, it is not industry or Federal Government Standard

30. What is P25? P25 Equipment Must demonstrate compliance
Meet the needs of public safety
Be Interoperable with other P25 equipment

31. Final Questions ? ?