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1 Scott Grimmett, BSEEScott Grimmett, BSEE
Interoperability Analysis Interoperability Analysis for DIGB 1for DIGB 1
By Scott Grimmett, BSEE By Scott Grimmett, BSEE
22 Scott Grimmett, BSEEScott Grimmett, BSEE
Scope of WorkScope of Work Three documented courses of actions Three documented courses of actions
(COA) pertaining to public safety voice (COA) pertaining to public safety voice interoperability communicationsinteroperability communications
Between each of the five Northern Idaho Between each of the five Northern Idaho Counties and the TribesCounties and the Tribes• KootenaiKootenai• ShoshoneShoshone• BonnerBonner• BoundaryBoundary• BenewahBenewah• Kootenai TribeKootenai Tribe• Coeur d’Alene Tribe Coeur d’Alene Tribe
33 Scott Grimmett, BSEEScott Grimmett, BSEE
Data GatheringData Gathering
Data gathering provided by each Data gathering provided by each county and tribes county and tribes
Data was limited Data was limited Most detailed data came from the Most detailed data came from the
agencies on the Kootenai and Bonner agencies on the Kootenai and Bonner County border and the Kootenai and County border and the Kootenai and Benewah County border. Benewah County border.
44 Scott Grimmett, BSEEScott Grimmett, BSEE
DeliverablesDeliverables
COA 1 will encompass interoperability COA 1 will encompass interoperability between all five northern countiesbetween all five northern counties
COA 2 will provide one detailed COA 2 will provide one detailed recommendation for interoperability recommendation for interoperability between Kootenai and Bonner Countiesbetween Kootenai and Bonner Counties
COA 3 will provide one detailed COA 3 will provide one detailed recommendation for interoperability recommendation for interoperability between Kootenai and Benewah Countiesbetween Kootenai and Benewah Counties
5 Scott Grimmett, BSEEScott Grimmett, BSEE
COA 1COA 1
Interoperability Analysis Interoperability Analysis for DIGB 1for DIGB 1
66 Scott Grimmett, BSEEScott Grimmett, BSEE
GoalGoal
Long term comprehensive plan for Long term comprehensive plan for interoperability between the five interoperability between the five northern counties, Benewah, Bonner, northern counties, Benewah, Bonner, Boundary, Kootenai, Shoshone, the Boundary, Kootenai, Shoshone, the Kootenai Tribe and the Coeur d’Alene Kootenai Tribe and the Coeur d’Alene tribe. tribe.
700 MHz P25 radio system and VHF 700 MHz P25 radio system and VHF conventional radio system conventional radio system
77 Scott Grimmett, BSEEScott Grimmett, BSEE
700 MHz P25 system 700 MHz P25 system
Two channels or talkgroups located at Two channels or talkgroups located at each 700 MHz site each 700 MHz site
One channel or talkgroup at each site will One channel or talkgroup at each site will be allocated to Fire/EMS and the other to be allocated to Fire/EMS and the other to Law Enforcement Law Enforcement
Where trunking systems are not available, Where trunking systems are not available, two 700 MHz conventional repeaters will two 700 MHz conventional repeaters will be needed be needed
ISSI connection capable of interfacing to ISSI connection capable of interfacing to the Statewide 700 MHz system the Statewide 700 MHz system
88 Scott Grimmett, BSEEScott Grimmett, BSEE
VHF SystemVHF System
Two channels Two channels One channel will be assigned for fire One channel will be assigned for fire
and EMS, and the other channel will and EMS, and the other channel will be used for law enforcement be used for law enforcement
Each channel will require a VHF P25 Each channel will require a VHF P25 capable repeater located at every capable repeater located at every VHF site defined in this study VHF site defined in this study
99 Scott Grimmett, BSEEScott Grimmett, BSEE
LinkingLinking
VHF Fire/EMS channel permanently VHF Fire/EMS channel permanently connected to the 700 MHz Fire/EMS connected to the 700 MHz Fire/EMS channel or talkgroup channel or talkgroup
VHF Law channel permanently connected VHF Law channel permanently connected to the 700 MHz Law channel or talkgroupto the 700 MHz Law channel or talkgroup
VHF and 700 MHz repeater systems should VHF and 700 MHz repeater systems should be connected through a P25 ISSIbe connected through a P25 ISSI
All sites connected All sites connected
1010 Scott Grimmett, BSEEScott Grimmett, BSEE
Interoperability Communication SiteInteroperability Communication Site
VHF Users 700 MHz Users
VHF Fire/EMS Channel
700 MHz Fire/EMS
Talkgroup
VHF Law Channel
700 MHz Law Talkgroup
Communications Site
1111 Scott Grimmett, BSEEScott Grimmett, BSEE
Microwave Linked Interoperability Microwave Linked Interoperability Communication Sites Communication Sites
VHF Fire/EMS Channel
700 MHz Fire/EMS Talkgroup
VHF Law Channel
700 MHz Law Talkgroup
Communications Site
VHF Fire/EMS Channel
700 MHz Fire/EMS Talkgroup
VHF Law Channel
700 MHz Law Talkgroup
Communications Site
Microwave Link
1212 Scott Grimmett, BSEEScott Grimmett, BSEE
Simulcast RepeatersSimulcast Repeaters
Repeater A Range Fo Fo
Repeater B Range
Repeater ARepeater B
All repeaters share the same input and output frequencies. All mobiles can talk to each other any where in the system.
Mobiles do not need to change frequencies (channel on the radio) when moving between repeaters
Fi Fi
Microwave
1313 Scott Grimmett, BSEEScott Grimmett, BSEE
P25 InterfacesP25 Interfaces
Common Air Interface (CAI) Subscriber Data Peripheral Interface Fixed Station Subsystem Interface (FSSI) Console Subsystem Interface (CSSI) Inter-RF Subsystem Interface (ISSI) Network Management Interface Data Network Interface Telephone Interconnect Interface
1414 Scott Grimmett, BSEEScott Grimmett, BSEE
Inter-RF Subsystem Interface (ISSI)
P25 RF P25 RF SubsystemSubsystem
P25 RF P25 RF SubsystemSubsystem
P25 RF P25 RF SubsystemSubsystem
P25 RF P25 RF SubsystemSubsystem
P25 RF P25 RF SubsysteSubsyste
mm
P25 RF P25 RF SubsysteSubsyste
mm
ISSIISSI
ISSIISSIISSIISSI
A non-proprietary interface that enables RF subsystems built by different manufacturers to be connected together into wide area networks.
1515 Scott Grimmett, BSEEScott Grimmett, BSEE
P25 ISSI
Non-proprietary interface IP based Interconnects radio systems built by
different manufacturers Connects systems operating in different
frequency bands Creates wide area radio networks for
extended coverage area for roaming subscriber units
Provides voice and data services, end-to-end encryption and roaming.
1616 Scott Grimmett, BSEEScott Grimmett, BSEE
Manufacturer X P25 System A
MasterSite
Manufacturer Y P25 System B
MasterSite
Unit A1 Unit A2
TG A100 TG A100
Unit B1
TG B150
Unit B2
TG B150
No ISSI – No interoperable No ISSI – No interoperable communications between systemscommunications between systems
1717 Scott Grimmett, BSEEScott Grimmett, BSEE
Manufacturer X P25 System A
MasterSite
Manufacturer Y P25 System B
MasterSite
Unit A1 Unit A2
TG A100
ISSI
TG A100
Unit B1
TG B150
Unit B2
TG B150
ISSI – Interoperable ISSI – Interoperable communications between systemscommunications between systems
1818 Scott Grimmett, BSEEScott Grimmett, BSEE
Manufacturer X P25 System A
MasterSite
Manufacturer Y P25 System B
MasterSite
Unit A1 Unit A2
TG A100
ISSI
Unit B1
TG B150
Unit B2
TG B150TG B150
Mode Change
ISSI Roaming– Mode change required ISSI Roaming– Mode change required between systemsbetween systems
1919 Scott Grimmett, BSEEScott Grimmett, BSEE
Why 700Why 700
It will continue to grow as the public It will continue to grow as the public safety radio system safety radio system
Recommended by the Idaho Statewide Recommended by the Idaho Statewide Interoperability Executive CouncilInteroperability Executive Council
Kootenai County Kootenai County Spokane County ISP and other state Spokane County ISP and other state
agenciesagencies SandpointSandpoint The Coeur d’Alene Tribe plans to migrate The Coeur d’Alene Tribe plans to migrate
700 MHz 700 MHz
2020 Scott Grimmett, BSEEScott Grimmett, BSEE
Why VHFWhy VHF
North Idaho terrain presents propagation North Idaho terrain presents propagation challenges for 700 MHzchallenges for 700 MHz
VHF radio signals bend and follow terrain VHF radio signals bend and follow terrain better than do 700 MHz signalsbetter than do 700 MHz signals
Some counties do not plan to use 700 Some counties do not plan to use 700 MHz systems MHz systems
The Forest Service, BLM, and Idaho The Forest Service, BLM, and Idaho Department of Lands plan to stay with Department of Lands plan to stay with VHF frequenciesVHF frequencies
2121 Scott Grimmett, BSEEScott Grimmett, BSEE
700 MHz Advantages/Disadvantages700 MHz Advantages/Disadvantages
AdvantagesAdvantages• Spectrum dedicated to public safetySpectrum dedicated to public safety• Less interference from other usersLess interference from other users• Lots of spectrum availableLots of spectrum available• TX and RX frequency spacing is goodTX and RX frequency spacing is good• Good building penetrationGood building penetration• Lower Noise FloorLower Noise Floor
DisadvantagesDisadvantages• Signal does not travel as farSignal does not travel as far• Signal does not bend over mountainsSignal does not bend over mountains• ExpensiveExpensive• More sites required to get same coverage as VHFMore sites required to get same coverage as VHF
2222 Scott Grimmett, BSEEScott Grimmett, BSEE
VHF Advantages/DisadvantagesVHF Advantages/Disadvantages
AdvantagesAdvantages• Signal travels furtherSignal travels further• Signal bends over mountains betterSignal bends over mountains better• Reasonability priced equipmentReasonability priced equipment• Reasonable building penetrationReasonable building penetration
DisadvantagesDisadvantages• The spectrum is crowdedThe spectrum is crowded• Hard to get new frequenciesHard to get new frequencies• Inference with other usersInference with other users• TX and RX frequency spacing is closeTX and RX frequency spacing is close
2323 Scott Grimmett, BSEEScott Grimmett, BSEE
Why MicrowaveWhy Microwave To communicate across the 5 To communicate across the 5
Northern Counties requires Northern Counties requires connectivity between radio sitesconnectivity between radio sites
The majority of the sites are on The majority of the sites are on remote mountain topsremote mountain tops
It is not practical to obtain fiber or It is not practical to obtain fiber or T1 lines these site locationsT1 lines these site locations
2424 Scott Grimmett, BSEEScott Grimmett, BSEE
Coverage GoalsCoverage Goals
700 MHz P25 radio coverage700 MHz P25 radio coverage• Interstate 90 corridor - 95%Interstate 90 corridor - 95%• US-95 corridor from the Canadian US-95 corridor from the Canadian
border to the northern border of Latah border to the northern border of Latah County - 95%County - 95%
• Population centers of the 5 northern Population centers of the 5 northern counties – 95%counties – 95%
VHF coverageVHF coverage• 5 northern counties of Idaho - 95% 5 northern counties of Idaho - 95%
2525 Scott Grimmett, BSEEScott Grimmett, BSEE
Coverage AssumptionsCoverage Assumptions VHFVHF
• 50-watt mobile transceiver, with a 3dB gain, omni-50-watt mobile transceiver, with a 3dB gain, omni-directional antenna. The antenna height is 2M (6.6-directional antenna. The antenna height is 2M (6.6-foot).foot).
• Transmitter sites will conform to the height above Transmitter sites will conform to the height above average terrain curves that are in Part 90 of the FCC average terrain curves that are in Part 90 of the FCC rules rules
• No transmitter site will exceed 200 watts ERP No transmitter site will exceed 200 watts ERP 700 MHz700 MHz
• 30-watt mobile transceiver, with a 3dB gain, omni-30-watt mobile transceiver, with a 3dB gain, omni-directional antenna. The antenna height is 2M (6.6-directional antenna. The antenna height is 2M (6.6-foot).foot).
MicrowaveMicrowave• Any one of the remote can to be destroyed by fire, Any one of the remote can to be destroyed by fire,
natural disaster, or terrorism without interruption to natural disaster, or terrorism without interruption to the remainder of the system.the remainder of the system.
2626 Scott Grimmett, BSEEScott Grimmett, BSEE
700 MHz Sites700 MHz Sites 1mi S SE of Border Mtn. 1mi S SE of Border Mtn. Dawson Ridge Dawson Ridge Black Mtn. Black Mtn. Sundance Mtn. Sundance Mtn. Schweitzer Mtn. Schweitzer Mtn. 4.7Mi E of Priest River 4.7Mi E of Priest River 1.7Mi NW of Gold Mtn. 1.7Mi NW of Gold Mtn. Canfield Mtn. Canfield Mtn. Mica Peak Mica Peak Killarney Mtn. Killarney Mtn. Hoodoo Mtn. Hoodoo Mtn. Mason Butte Mason Butte Goose Hump Goose Hump Wardner Peak Wardner Peak Silverton Silverton Lookout Pass Lookout Pass Tekoa Mtn. Tekoa Mtn. St. Maries Court House St. Maries Court House
2727 Scott Grimmett, BSEEScott Grimmett, BSEE
700 MHz Coverage – 30 dB700 MHz Coverage – 30 dB
2828 Scott Grimmett, BSEEScott Grimmett, BSEE
Northern 700 MHz Coverage – 30 Northern 700 MHz Coverage – 30 dBdB
2929 Scott Grimmett, BSEEScott Grimmett, BSEE
Central 700 MHz Coverage – 30 dBCentral 700 MHz Coverage – 30 dB
3030 Scott Grimmett, BSEEScott Grimmett, BSEE
Sothern 700 MHz Coverage – 30 Sothern 700 MHz Coverage – 30 dBdB
3131 Scott Grimmett, BSEEScott Grimmett, BSEE
VHF SitesVHF Sites 1mi S SE of Border Mtn. 1mi S SE of Border Mtn. Dawson Ridge Dawson Ridge Black Mtn. Black Mtn. Sundance Mtn. Sundance Mtn. Schweitzer Mtn. Schweitzer Mtn. 4.7Mi E of Priest River 4.7Mi E of Priest River 1.7Mi NW of Gold Mtn. 1.7Mi NW of Gold Mtn. Canfield Mtn. Canfield Mtn. Mica Peak Mica Peak Killarney Mtn. Killarney Mtn. Hoodoo Mtn. Hoodoo Mtn. Mason Butte Mason Butte Goose Hump Goose Hump Wardner Peak Wardner Peak Silverton Silverton Lookout Pass Lookout Pass Tekoa Butte Tekoa Butte St Joe BaldySt Joe Baldy Bald Mtn.Bald Mtn.
3232 Scott Grimmett, BSEEScott Grimmett, BSEE
VHF Coverage – 30 dBVHF Coverage – 30 dB
3333 Scott Grimmett, BSEEScott Grimmett, BSEE
Northern VHF Coverage – 30 dBNorthern VHF Coverage – 30 dB
3434 Scott Grimmett, BSEEScott Grimmett, BSEE
Central VHF Coverage – 30 dBCentral VHF Coverage – 30 dB
3535 Scott Grimmett, BSEEScott Grimmett, BSEE
Northern VHF Coverage – 30 dBNorthern VHF Coverage – 30 dB
3636 Scott Grimmett, BSEEScott Grimmett, BSEE
Microwave SitesMicrowave Sites 1mi S SE of Border Mtn.1mi S SE of Border Mtn. Copeland uW Relay Copeland uW Relay Dawson Ridge Dawson Ridge Black Mtn. Black Mtn. Sundance Mtn. Sundance Mtn. Schweitzer Mtn. Schweitzer Mtn. 4.7Mi E of Priest River 4.7Mi E of Priest River 1.7Mi NW of Gold Mtn. 1.7Mi NW of Gold Mtn. Canfield Mtn. Canfield Mtn. Mica Peak Mica Peak Killarney Mtn. Killarney Mtn. Hoodoo Mtn. Hoodoo Mtn. Mason Butte Mason Butte Goose Hump Goose Hump Wardner Peak Wardner Peak Silverton Silverton Lookout Pass Lookout Pass Tekoa Mtn. Tekoa Mtn. St Joe BaldySt Joe Baldy Bald Mtn.Bald Mtn. St. Maries Court House St. Maries Court House
3737 Scott Grimmett, BSEEScott Grimmett, BSEE
Microwave LinksMicrowave Links
3838 Scott Grimmett, BSEEScott Grimmett, BSEE
COA 2 and 3COA 2 and 3
No changes to the current VHF, UHF, No changes to the current VHF, UHF, and 700 MHz systems and 700 MHz systems
Based on feedback received from the Based on feedback received from the recent user surveys recent user surveys
May be other areas where May be other areas where interoperable communication may interoperable communication may remain an unidentified problem due remain an unidentified problem due to limited feedback to limited feedback
3939 Scott Grimmett, BSEEScott Grimmett, BSEE
40 Scott Grimmett, BSEEScott Grimmett, BSEE
COA 2COA 2
Interoperability Analysis Interoperability Analysis for DIGB 1for DIGB 1
4141 Scott Grimmett, BSEEScott Grimmett, BSEE
Course of Action 2: Course of Action 2: Bonner County – Kootenai County BorderBonner County – Kootenai County Border
Regular Mutual AideRegular Mutual Aide KootenaiKootenai
• Sprit Lake FireSprit Lake Fire• Timber Lake FireTimber Lake Fire• Northern Lakes FireNorthern Lakes Fire
BonnerBonner• Sagle FireSagle Fire• West Pend Oreille FireWest Pend Oreille Fire
4242 Scott Grimmett, BSEEScott Grimmett, BSEE
Assumed requirements Assumed requirements Each vehicle will carry only one two-way Each vehicle will carry only one two-way
radio. radio. Mutual aid vehicles will move the mutual Mutual aid vehicles will move the mutual
aid channel as soon as possible after aid channel as soon as possible after being dispatched.being dispatched.
Equipment required to provide the Equipment required to provide the mutual aid on a regular basis will be mutual aid on a regular basis will be permanently installed. permanently installed.
All on-scene tactical communications will All on-scene tactical communications will be facilitated through low-power cross-be facilitated through low-power cross-band vehicular repeaters installed in the band vehicular repeaters installed in the command vehicles and larger fire assets.command vehicles and larger fire assets.
4343 Scott Grimmett, BSEEScott Grimmett, BSEE
Sagle Fire and West Pend Oreille Fire VHF Sagle Fire and West Pend Oreille Fire VHF provide aide to Spirit Lake Fire and Timber provide aide to Spirit Lake Fire and Timber
Lake Fire 700 MHzLake Fire 700 MHz Hoodoo Mountain VHF repeater to 700 Hoodoo Mountain VHF repeater to 700
MHz gatewayMHz gateway Little Blacktail VHF repeater to 700 MHz Little Blacktail VHF repeater to 700 MHz
gatewaygateway Create a Fire Operations South Talkgroup Create a Fire Operations South Talkgroup
on the 700 MHz system - on the 700 MHz system - IK Fire Ops IK Fire Ops North North
Kootenai County agencies use the 700 Kootenai County agencies use the 700 MHz talkgroup and Bonner County MHz talkgroup and Bonner County agencies use the VHF repeater for agencies use the VHF repeater for interoperability communications. interoperability communications.
4444 Scott Grimmett, BSEEScott Grimmett, BSEE
Hoodoo VHF repeater gateway to Hoodoo VHF repeater gateway to Kootenai 700 MHz talkgroupKootenai 700 MHz talkgroup
4545 Scott Grimmett, BSEEScott Grimmett, BSEE
Blacktail VHF repeater gateway to Blacktail VHF repeater gateway to Kootenai 700 MHz talkgroupKootenai 700 MHz talkgroup
VHF Repeater
700 MHz P25 Mobile
Gateway Controller
Duplexer
Little Blacktail VHF Interoperability
Repeater Kootenai 700 MHz System FIRE OPS North Talkgroup
4646 Scott Grimmett, BSEEScott Grimmett, BSEE
VHF coverage from Hoodoo and VHF coverage from Hoodoo and Little Blacktail – 20 dBLittle Blacktail – 20 dB
4747 Scott Grimmett, BSEEScott Grimmett, BSEE
VHF coverage from Hoodoo and VHF coverage from Hoodoo and Little Blacktail – 30 dBLittle Blacktail – 30 dB
4848 Scott Grimmett, BSEEScott Grimmett, BSEE
Sprit Lake, Timber Lake and Northern Lake Fire Sprit Lake, Timber Lake and Northern Lake Fire 700 MHz aide to Sagle Fire and West Pend 700 MHz aide to Sagle Fire and West Pend
Oreille Fire VHFOreille Fire VHF 700 MHz to VHF gateway in Sandpoint700 MHz to VHF gateway in Sandpoint 800 MHz repeater to VHF gateway on Little 800 MHz repeater to VHF gateway on Little
Blacktail Blacktail 800 MHz repeater to VHF gateway at Stimpson 800 MHz repeater to VHF gateway at Stimpson
Lumber Lumber Create a Fire Operations South Talkgroup on the Create a Fire Operations South Talkgroup on the
700 MHz system - 700 MHz system - 7B-Fire-Ops-South7B-Fire-Ops-South Kootenai County Agencies use the 700 MHz Kootenai County Agencies use the 700 MHz
talkgroup and 800 MHz repeater while Bonner talkgroup and 800 MHz repeater while Bonner County agencies use the VHF repeater for County agencies use the VHF repeater for interoperability communications. interoperability communications.
4949 Scott Grimmett, BSEEScott Grimmett, BSEE
Bonner VHF to Kootenai 700 MHz Bonner VHF to Kootenai 700 MHz GatewayGateway
VHF Mobile700 MHz P25 Mobile
Gateway Controller
Bonner VHF Fire Repeater on Baldy
Kootenai 700 MHz System
Bonner Fire Operations Talkgroup
5050 Scott Grimmett, BSEEScott Grimmett, BSEE
Blacktail 800 MHz Repeater to Blacktail 800 MHz Repeater to Bonner VHF GatewayBonner VHF Gateway
800 MHz Repeater
VHF Mobile
Gateway Controller
Duplexer
Bonner VHF Fire Repeater on Baldy
800 MHz Repeater on Little Blacktail
5151 Scott Grimmett, BSEEScott Grimmett, BSEE
Stimson 800 MHz Repeater to Stimson 800 MHz Repeater to Bonner VHF GatewayBonner VHF Gateway
800 MHz Repeater
VHF MobileGateway Controller
Duplexer
Bonner VHF Fire Repeater on Baldy
800 MHz Repeater at Stimson Lumber
5252 Scott Grimmett, BSEEScott Grimmett, BSEE
700/800 MHz coverage into Bonner 700/800 MHz coverage into Bonner County – 20 dBCounty – 20 dB
5353 Scott Grimmett, BSEEScott Grimmett, BSEE
700/800 MHz coverage into Bonner 700/800 MHz coverage into Bonner County – 30 dBCounty – 30 dB
5454 Scott Grimmett, BSEEScott Grimmett, BSEE
On-Scene InteroperabilityOn-Scene Interoperability
A vehicular repeater provides a local, low A vehicular repeater provides a local, low power link between VHF portable radios power link between VHF portable radios and 700/800 MHz portable radios. and 700/800 MHz portable radios.
Vehicular repeaters in command vehicles Vehicular repeaters in command vehicles and larger fire assets are necessary and larger fire assets are necessary because they allow handheld radios from because they allow handheld radios from different districts with different frequency different districts with different frequency bands to communicate with one another bands to communicate with one another on site. on site.
5555 Scott Grimmett, BSEEScott Grimmett, BSEE
Bonner Fire/EMS Vehicular Bonner Fire/EMS Vehicular RepeatersRepeaters
VHF Mobile Radio
800 MHz Vehicular Repeater
Home VHF TAC
Frequency
Neighbor 800 MHz Vehicular Repeater
Frequency
Home County VHF Portable
Radios
Neighbor County 800 MHz Portable
Radios
5656 Scott Grimmett, BSEEScott Grimmett, BSEE
Kootenai Fire/EMS Vehicular Kootenai Fire/EMS Vehicular RepeatersRepeaters
800 MHz Mobile Radio
VHF Vehicular Repeater
Home 800 MHz TAC
Frequency
Neighbor VHF Vehicular Repeater
Frequency
Home County 800 MHz Portable
Radios
Neighbor County VHF Portable
Radios
57 Scott Grimmett, BSEEScott Grimmett, BSEE
Trunking RepeatersTrunking Repeaters
Interoperability Analysis Interoperability Analysis for DIGB 1for DIGB 1
5858 Scott Grimmett, BSEEScott Grimmett, BSEE
What is trunking?What is trunking?
A large group of users sharing a pool of A large group of users sharing a pool of frequencies.frequencies.
The system infrastructure is shared by all The system infrastructure is shared by all the users and for multiple purposes.the users and for multiple purposes.
Unlike conventional radios where each Unlike conventional radios where each repeater is designated for a separate repeater is designated for a separate purpose.purpose.
5959 Scott Grimmett, BSEEScott Grimmett, BSEE
Trunking Sharing Example Trunking Sharing Example
6060 Scott Grimmett, BSEEScott Grimmett, BSEE
Trunking System ExampleTrunking System Example
Freq 1
Freq 2
Freq 3
Freq 4
Freq 5
6161 Scott Grimmett, BSEEScott Grimmett, BSEE
Trunking System ExampleTrunking System Example
Trunking takes the advantage of the Trunking takes the advantage of the fact that not every agency will need fact that not every agency will need to transmit at exactly the same time.to transmit at exactly the same time.
Statistically, more than 5 agencies Statistically, more than 5 agencies can be having a conversation on the can be having a conversation on the 5 channels without interruption of 5 channels without interruption of each conversation. each conversation.
6262 Scott Grimmett, BSEEScott Grimmett, BSEE
Trunking Blocking ExampleTrunking Blocking Example
6363 Scott Grimmett, BSEEScott Grimmett, BSEE
Trunking Repeater SystemTrunking Repeater System
Site A Range
Site B Range
Site A Site B
Each site has a pool of frequencies. The site hardware uses a base station for each frequency which are combined together into one transmit and one receive antenna per site. The sites
are tied together via Fiber, T1, and/or Microwave and controlled by a trunking controller.
Multiple Frequencies
Multiple Frequencies
6464 Scott Grimmett, BSEEScott Grimmett, BSEE
Talkgroups not ChannelsTalkgroups not Channels
In trunking, do not think of the In trunking, do not think of the channels as different frequencies channels as different frequencies instead think of the channels as instead think of the channels as different talkgroups. different talkgroups.
With trunking you decide who you With trunking you decide who you want to talk with instead of what want to talk with instead of what frequency to use.frequency to use.
6565 Scott Grimmett, BSEEScott Grimmett, BSEE
Trunking Repeater SystemTrunking Repeater System
Site A Range
T1T1
Site B Range
Site A Site B
T2 T1
Mobiles communicate with every radio in the same talk group regardless of where they are in the system. There is no need to
change channels while moving throughout the system. Talk groups can be patched together for mutual aid.
T2
T3
T3
6666 Scott Grimmett, BSEEScott Grimmett, BSEE
FCC Rule 90.205FCC Rule 90.205
6767 Scott Grimmett, BSEEScott Grimmett, BSEE
ERP is: ERP is: ERPallow = ERPallow = ERPmax x (HAATref / ERPmax x (HAATref / HAATactual)HAATactual). .
Hoodoo ExampleHoodoo Example Example: The HAAT is 661 Example: The HAAT is 661
meters. Using the formula meters. Using the formula the ERP would be:the ERP would be:
Allowable ERP = 500 * 670/ Allowable ERP = 500 * 670/ 667 = 667 = 502.2 watts ERP502.2 watts ERP (80 kilometer radius)(80 kilometer radius)
Allowable ERP = 500 * 110/ Allowable ERP = 500 * 110/ 667 = 667 = 82.4 watts ERP82.4 watts ERP (40 kilometer radius)(40 kilometer radius)
Requested Service Area
Max ERP Max (Ref) HAAT
(Meters)
3 kilometers 1 watts 15
8 kilometers 28 watts 15
13 kilometers 178 watts 15
16 kilometers 500 watts 15
24 kilometers 500 watts 33
32 kilometers 500 watts 65
40 kilometers 500 watts 110
48 kilometers 500 watts 160
64 kilometers 500 watts 380
80 kilometers 500 watts 670