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Author Topic: repeater setup for fire/EMS use question  (Read 1737 times)

YONU

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repeater setup for fire/EMS use question
« on: October 10, 2018, 12:54:09 PM »

ok all I have a question for you as I am a ham and on the local VFD the fire chief asked me if i could do some research on setting up a small repeater as the handhelds don't get out far enough to reach dispatch during calls and it is up the each vfd to deal with their own repeaters here rather than the county from what i was told.  The question I have is this the operating freq is this would a 65ft tower be high enough to handle a repeater than only needs to cover a 12mile area of flat ground i am still waiting to hear back from the county to on who handles the licensing them or the vfd.  Basically i need advise on equipment as this can't be crossband and i will be honest i have never totally understood how far apart to put antennas when 2 transmitters are in the same band.

Thanks,
KK4NJC
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W9IQ

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RE: repeater setup for fire/EMS use question
« Reply #1 on: October 10, 2018, 01:40:19 PM »

From a legal perspective, you must get a license from the FCC to have a commercial repeater. If the current FD license is only for individual radios, you will need to submit a new application and obtain a coordinated frequency from an FCC approved frequency coordinator. Unlike a ham radio repeater, you cannot cobble together any old transmitter and receiver to build the repeater. It must be FCC certified/approved for Part 90 service - more specifically, the transmitter must meet this requirement. You will need to supply antenna height information, antenna gain, power, expected radius of coverage, your assigned coordinated frequencies, etc. as part of the application.

From a technical perspective, do not guess at coverage. "Flat" land is quite relative. You should use appropriate software to model your intended repeater location, height, power, receive sensitivity, duplexer loss, and antenna system gain along with the local topography to ensure that you obtain the intended coverage.

A free, on-line program that you can use for coverage modeling can be found at: http://www.ve2dbe.com/rmonline.html. There are several other packages that will serve the same purpose.

- Glenn W9IQ
« Last Edit: October 10, 2018, 01:47:59 PM by W9IQ »
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

N8EKT

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RE: repeater setup for fire/EMS use question
« Reply #2 on: October 10, 2018, 07:23:01 PM »

From a legal perspective, unlike ham repeaters, if
a fire repeater fails to work, a wrongful death
suit may occur so i would call a professional two-way
shop and let them take on the liability.
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W9IQ

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RE: repeater setup for fire/EMS use question
« Reply #3 on: October 11, 2018, 03:08:57 AM »

From a legal perspective, unlike ham repeaters, if
a fire repeater fails to work, a wrongful death
suit may occur so i would call a professional two-way
shop and let them take on the liability.


I think that is generally good advice although in this case the department probably carries a significant liability policy or there are statutory limitations of liability as a VFD. It might be worth checking if installing a repeater would be covered if you feel you have the technical acumen and the desire to tackle such a project.

- Glenn W9IQ
« Last Edit: October 11, 2018, 03:21:54 AM by W9IQ »
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KA5IPF

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RE: repeater setup for fire/EMS use question
« Reply #4 on: October 11, 2018, 08:28:25 AM »

From a legal perspective, unlike ham repeaters, if
a fire repeater fails to work, a wrongful death
suit may occur so i would call a professional two-way
shop and let them take on the liability.


Lawyeritis infects every facet of life today.
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K4JJL

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RE: repeater setup for fire/EMS use question
« Reply #5 on: October 11, 2018, 08:48:17 AM »

From a legal perspective, unlike ham repeaters, if
a fire repeater fails to work, a wrongful death
suit may occur so i would call a professional two-way
shop and let them take on the liability.


Lawyeritis infects every facet of life today.

When I drove to Birmingham last week, 75% of the billboard looked like this...

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K1XS

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RE: repeater setup for fire/EMS use question
« Reply #6 on: October 19, 2018, 08:51:45 AM »

From a legal perspective, you must get a license from the FCC to have a commercial repeater. If the current FD license is only for individual radios, you will need to submit a new application and obtain a coordinated frequency from an FCC approved frequency coordinator. Unlike a ham radio repeater, you cannot cobble together any old transmitter and receiver to build the repeater. It must be FCC certified/approved for Part 90 service - more specifically, the transmitter must meet this requirement. You will need to supply antenna height information, antenna gain, power, expected radius of coverage, your assigned coordinated frequencies, etc. as part of the application.
- Glenn W9IQ

This is 100% correct.  I'm a retired fire chief, 33 years in the FD, and spent 10 years working with our radio vendor to maintain and improve our radios and two repeaters.  One point on the coordinated pair, depending on where the FD is located it may be difficult to get another VHF or UHF frequency for a repeater input.

Unfortunately liability is a concern but more importantly is the injury or death that could occur when a home brew system fails.  Part 90 systems used in public safety are much more robust, and expensive, than amateur gear partly due to the inherent risk associated with equipment failure.

You could look them up in the FCC database to see if the VFD or county holds the license:

http://wireless2.fcc.gov/UlsApp/UlsSearch/searchGeographic.jsp

Ken
K1XS
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W9FIB

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RE: repeater setup for fire/EMS use question
« Reply #7 on: October 19, 2018, 10:07:06 AM »

From a legal perspective, you must get a license from the FCC to have a commercial repeater. If the current FD license is only for individual radios, you will need to submit a new application and obtain a coordinated frequency from an FCC approved frequency coordinator. Unlike a ham radio repeater, you cannot cobble together any old transmitter and receiver to build the repeater. It must be FCC certified/approved for Part 90 service - more specifically, the transmitter must meet this requirement. You will need to supply antenna height information, antenna gain, power, expected radius of coverage, your assigned coordinated frequencies, etc. as part of the application.
- Glenn W9IQ

This is 100% correct.  I'm a retired fire chief, 33 years in the FD, and spent 10 years working with our radio vendor to maintain and improve our radios and two repeaters.  One point on the coordinated pair, depending on where the FD is located it may be difficult to get another VHF or UHF frequency for a repeater input.

Unfortunately liability is a concern but more importantly is the injury or death that could occur when a home brew system fails.  Part 90 systems used in public safety are much more robust, and expensive, than amateur gear partly due to the inherent risk associated with equipment failure.

You could look them up in the FCC database to see if the VFD or county holds the license:

http://wireless2.fcc.gov/UlsApp/UlsSearch/searchGeographic.jsp

Ken
K1XS

Yep, both are correct. As a retired fireman I can assure you they are 100% on the mark.

You may also want to check at the county level. We have 12 Fire/EMS departments in our county that all utilize the same frequencies county wide so departments can interact during a mutual aid situation. Your county may have something similar. Just another avenue to look down.
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73, Stan
Travelling the world one signal at a time.

K6AER

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RE: repeater setup for fire/EMS use question
« Reply #8 on: October 25, 2018, 07:50:16 AM »

You mentioned a 12 mile area. is that 12 by 12 mile square, 12 mile radius or 12 square miles.

Height coverage is the sq. root of twice the tower height

12 X 12 =144. 144/2 = 72 feet of tower height. You would want at least a 6 dBd antenna and low loss coax or hard line. a 50 watt repeater should work fine. Most commercial repeaters  (kenwood  or Icom) will run you about $3000. Cavities will cost about $2000.

The repeater should be run on a 250 amp battery system with commercial charging system....costing about $1500.
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KT4NR

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RE: repeater setup for fire/EMS use question
« Reply #9 on: October 29, 2018, 09:44:06 AM »

Your best action is contact county dispatch/radio shop and coordinate with them. You don't want to just throw something up willy nilly as has been noted in the previous posts. Your County emergency management may have resources for you to use as well.
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