BCoFD Radio Overview

1. BALTIMORE COUNTY Motorola TrunkingRadio System Overview

2. Baltimore Co Trunking System

- Project 25 Compliant- Standards for digital radiocommunications so agencies can communicate with mutual aid response teams in emergencies

- All Digital - Improves clarity & voice quality

- Simulcast System Offers a larger coverage area

- Increased Frequency Availability

Multiple Talkgroups/Channels per entity

Eff icient use of frequencies (Channels are only used when Talkgroup members are transmitting).

2 Zones -North-South

18 Tower Sites

- Nationwide Emergency Interoperability

Public Safety Nationwide frequencies

- Emergency Alerting Capability

- Voice Encryption (Secure)

3. North Simulcast Site (3 tower sites/12 channels) Route 439Spook HillHereford (Prime Site) South Simulcast Site (15 tower sites/24 channels) ArcadiaMEMA WarrenJacksonville Red RunFire Headquarters (Prime Site) HickeyKingsville Highway Shop 2Essex AllenderCatonsville North PointBrady Avenue Sparrows Point Backup Prime Site for Both the North & South Simulcast system Gilroy BALTIMORE COUNTY TOWER SITE LOCATIONS 4. THE NEW P25 SYSTEM

Digital Trunking

A digital radio transmitter processes sounds into patterns of numbers, or "digits"

Frequencies are pooled and assigned when the radio user presses the PTT button

Advantages

Users have access to more Talkgroups/Channels

Utilizes idle frequencies and frequencies are available to all users

5. TRUNKING In two-way radio communications,Trunkingrefers to the automatic and dynamic sharing of a small number of radio channels among a large number of radio users. A Trunking System efficiently distributes message traffic across the available channels and reduces wait time for those channels. 6. Talkgroup A Police 1 2 3 4 5 Trunking allows individual users to be combined intoTalkgroups . ATALKGROUP is a group of users that have a common need to communicate with each other in order to accomplish their job. Talkgroups Talkgroup B Fire/EMS 7. The Motorola Trunked radio system uses a computercalled theZone Controlleras an operator.TheZoneController has 2 PRIMARY DUTIES: FIRST,to insure that only radios programmed for yourspecific Trunking system are used on the network. SECONDLY,to maintain and distribute the frequenciesor channels on the network.Zone Controller 8.

One of the frequencies/channels at each tower site is programmed to

operate as theCONTROL CHANNEL.

The Control Channels job is to keep track of the radios affiliated

with each tower and know which Talkgroup/Channel is selected

on the radio.

If I turn the Talkgroup/Channel selector one click, my radio sends

two messages to the control channel.I am leaving this

Talkgroup/Channel and I am arriving at the newly selected

Talkgroup/Channel.

The Control Channel carries only data and cannot be used for

voice communications.

Control Channel 9.

When you turn your radio on, it affiliates with the network through the Control Channel on the site nearest your location.

When no one is transmitting on your selected Talkgroup/Channel,your

radio is still talking to the Control Channel.(Note: This transmission is

transparent to the user.)

Your radios may be programmed with Talk Permit Tones.

You should not begin your transmission before you hear the tones.

Turning On Your Radio 10. Step 1: The following is an example of what occurs between the time you press the PTT (Push-to-Talk) button and the time you hear the Talk Permit Tones (less than second). In this example, Channel 1 is the Control Channel and Channels 2 through 5 are voice channels. When you press the PTT button, the Control Channel receives the request and forwards the request to the Zone Controller that a radio is on. Talkgroup/Channel B wants to talk to all other users on the system selected to the same Talkgroup/Channel. Call Processing Event Sequence 11. The Zone Controller then communicates with the Control Channel at every tower and asks if they have any radios turned to Talkgroup/Channel B affiliated on their site. Based on the replies from the Control Channels, the Zone Controller reaches into the pool and chooses a specific frequency for the transmission.In our example, this is Channel 5. The Zone Controller then sends a messageto all of the Control Channels that if they haveany users selected to Talkgroup/Channel B,they should send those users to Channel 5. Step 2: Step 3: Step 4: Step 4 Call Processing Event Sequence (Cont) 12. All radios monitoring the Control Channel receive this message and travel over to Channel 5. Step 5: Voice Call Processing Event Sequence (Cont) 13. Step 6:

When the transmission is completed, all of the radios selected to Talkgroup/Channel

B automatically return to the Control Channel.

The previously assigned voice channel returns to the pool and is available for other

transmissions. ( NOTE: This process may occur multiple times during a conversation and is

transparent to the radio users.)

The radio user never knows what specific frequency they are transmitting on and

they dont care. They are primarily concerned that they can transmit to and receive

from other radio users selected to the same Talkgroup/Channel.

Voice The Zone Controller promises the radio users that if they are selected to the same Talkgroup/Channel and affiliated withanytower on the system, they will be able to communicate with each other. Step 6: Call Processing Event Sequence (Cont) 14.

Trunking systems are designed or sized based on the concept that:

It is highly improbable that a large number of users will want to transmit atexactly the same time.

It is important to remember that whether you have two radios or 200 radios selected to the same Talkgroup/Channel, they only use one frequency.

And that most conversations are relatively short.

The system has aTime out Timer

set to 30 seconds. If you have the

PTT pressedcontinuously for

26 seconds, you will begin to hear

a dull tone.At 30 seconds, the

Zone Controller will take the

channel away from you. Your

transmission will no longer be

heard and you must release the PTT and press it again for the radio to receive a new channel assignment.

Trunking System Design 15. The first tone is aTalkgroup/Channel Busy What is a Talkgroup/ChannelBusy? When a radio user attempts to key uptheir radio and the Talkgroup/Channelwhere they are selected is alreadytransmitting (i.e.talkover another user),they will receive a Talkgroup/Channel Busyprohibit tone. There are two types of Busy tones that you may receive on the trunking system.Trunking System Design (Cont) 16.

What should I do if I hear a Talkgroup/Channel Busy tone?

Release the PTT button and listen for other transmissions.

When the transmission ends, press the PTT button, wait

for the Talk Permit tones then begin transmitting.

N OTE: The radios also hang around on the channel for a few seconds

after the user releases the PTT. During this hang timeno

transmission is heard.

If this occurs, wait a few seconds and press the PTT.

You will hear the same tone when you are out of range of the trunking

system.In this case, in addition to the tone, an OUT OF RANGE message

will appear on the display of your radio.

Trunking System Design (Cont) 17.

The second tone is a System Busy tone

What is a System Busy tone?

If the radio user presses the PTT and no channels are available for assignment, the user will receive a System Busy tone.

What should I do if I receive a System Busy tone?

Release the PTT button and wait for the three quick Talk Permit

Tones. Within three seconds of hearing these tones, press and hold the

PTT button to transmit your message.

NOTE:After receiving the Talk Permit Tones, the radio user must press the PTT within three seconds or the channel will be reassigned to the next user in the queue.

Trunking System Design (Cont) 18.

Trunking Systems contain many layers of redundancy or back-up to ensure that communications continue even in extreme situations.

Back-up modes that are transparent to the radio user are:

Rotation of Control Channels

Repeater skipped if off the air

Redundant communication methods

connecting infrastructure

Back-up modes that are visibleto the radio user are:

Site Trunking

Failsoft

Introduction to Radio SystemBack-up Modes 19.

How does this affect the radio user?

Radios operate as they would in a normal Trunking environment

The radio will display Site Trunking

Youwillhave PTT tones

Youwillstill be able to communicate with users in your Zone

(you will not be able to communicate with users in other Zones)

Your EMERGENCY button will work, but may not be displayed onthe console in the Dispatch Center

Communication with your Dispatch Center may be limited

Site Trunking - The Zone Controller has lost communications with the Site(s). Site Trunking 20.

Examples of Major Failures :

Both Zone Controllers Fail

All Four Control Channels Fail

All Voice Channels Fail

What happens to the radios in Failsoft?

Radios operate as they would on a conventional repeater system

Each channel is mapped to a specific frequency

A low level alert tone is broadcast every 10 seconds

FAILSOFT is displayed on the radio

PTT Tones are not available

You will hear transmissions from multiple Talkgroups on your Channel

The Emergency button functionality is not available

What should the radio user do?

If you are on the Talkgroup/Channel where you should be assigned, leave the radio

where it is selected and listen for transmissions.

If not, you should select the Talkgroup/Channel where you should be assigned and listen for transmissions.

Failsoft at the Zone Level The Zone Controller has failed. ( This occurrence is extremely rare.) Failsoft 21.