conventional vs. trunking radio systems awin network support basic level overview

Conventional vs. Trunking Radio SystemsAWIN NETWORK SUPPORT

BASIC LEVEL OVERVIEW

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?

What is AWIN?

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.

Trunking Radio Systems – Basic Overview

Site Controller

Channel 1Control Channel

Channel 2Alt. Control

ChannelChannel 3 Channel 4 Channel 5

Zone Controller

Trunking Radio Systems – Basic OverviewWhat 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.

Trunking vs. Conventional Radio Systems

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•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., 155.555 MHz is County Sheriff, 156.555 is County Fire)

• Each frequency is assigned to a group of users.


•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.


•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


•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”.


•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.

How Does Trunking Work?

Site Controller


RX/TX


ChannelRX/TX

Channel 3RX/TX

Channel 4RX/TX

Channel 5RX/TX

Zone Controller

Control Channel continuouslyTransmits system data to all radios


Site Controller


RX/TX


ChannelRX/TX

Channel 3RX/TX

Channel 4RX/TX

Channel 5RX/TX

Zone Controller

Radio user presses TX button.The radio information is sent via the control channelTo the site controller


Site Controller


RX/TX


ChannelRX/TX

Channel 3RX/TX

Channel 4RX/TX

Channel 5RX/TX

Zone Controller

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


Site Controller


RX/TX


ChannelRX/TX

Channel 3RX/TX

Channel 4RX/TX

Channel 5RX/TX

Zone Controller

The original radio user’s radio automatically switches toThe correct voice channel and begins transmitting; All radios selected on the same Talk Group do the same and hear the voice transmission

How Does Trunking Work?Radio System Fleet Mapping:Radio “Channels” are nowCalled “Talk Groups”.

(Example Law EnforcementShown Here)

Radio Zone 1 2

Dispatch 1TG ID# XXXXXXTG ALIAS

MAC CALLTG ID# XXXXXXTG ALIAS

Dispatch 2TG ID# XXXXXXTG ALIAS

MAC 1TG ID# XXXXXXTG ALIAS

CIDTG ID# XXXXXXTG ALIAS


ADMINTG ID# XXXXXXTG ALIAS


Questions…so far?

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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.


•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”)


•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


Site 1

Site 2

Site 3

SimulcastSite 5

f1 f2 f3 f4 f5f1 f2 f3 f4 f5

f1 f2 f3 f4 f5


•Simulcast Issues

• Amplitude and frequency of transmitted signals must be very accurately timed to ensure

good signal quality.

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

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?


•Analog vs. Digital

Analog Transmission

Digital Transmission

Information is sent by changing the frequency, amplitude, or phase of the radio signal.

Information is converted to true data bits and applied directly to the radio transmitter using FDMA (or TDMA or CDMA)


•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

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

What is P25?

•P25 Equipment

• Must demonstrate compliance

• Meet the needs of public safety

• Be Interoperable with other P25 equipment

Final Questions

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conventional vs. trunking radio systems awin network support basic level overview

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