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Old 12-12-2017, 10:36 AM
  Audio Feed Provider
Audio Feed Provider
Join Date: Feb 2009
Location: Holly Springs, NC
Posts: 15
Default adding a 900mhz repeater to our fire station roof

Hello friends-

A 3rd party company is interested in adding a 900mhz repeater to the roof of our fire station. This will be used for remote meter reading. We currently use a 800mhz radio system as well as a UHF system for dispatching. Is there a possibility that this can cause interference with out public safety radios? Do they need to a be a specific distance apart? We have just recently found out about this project so i am trying to do a little bit of research. I have also asked for some sort of documentation stating it would not interfere but im not sure if i will get that.

Any help is greatly appreciated and if this is in the wrong section please let me know so i can move it to the correct place.

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Old 12-12-2017, 1:45 PM
mmckenna's Avatar
Join Date: Jul 2005
Location: WTVLCA01DS0
Posts: 7,924

I've got a few similar situations at a few of my radio sites. Most of it's cellular carriers coming in, but same stuff applies…

There should be some sort of contract to lease the site. That should including how much they are paying (if it's a commercial entity), how long the lease is for, renewal/termination terms, etc. Stuff that should be handled by your city/county attorney/legal department.
If this is a commercial utility or similar, make sure there is a contract for the site. Don't let them put something out there without rules.

Those rules should include (but not limited to) the following:
Specific verbage about what they are installing. Including specs on the radio, antenna, etc.
Specifics about electrical connections, if any.
Specifics about how the equipment is installed, up to code, inspected, etc.
Specifics about what happens if/when the lease is terminated, including removing -all- equipment and restoring the site to original condition ( should include holes plugged, all gear removed, clean up, etc)

There should absolutely be a section about how in the event of interference, there is a set time to fix the issue, like 24 hours or less. If it's not fixed, the equipment gets shut down. Use specific wording about life safety radio systems and the importance of no interference. That way if there is an issue, you've got some control over the situation. If you don't do this, it can turn into a bunch of finger pointing and that's a big issue.

If everything is installed correctly using proper cable, connectors, radios, etc. - AND - there is appropriate separation between the antennas, there shouldn't be an issue. Usually these meter reader radios are low power, so that reduces the chances. Likely they'll be more concerned about interference from your stuff, as your radios will be running higher power.

There's a lot of things that can cause interference, so it's hard to give you a 100% answer, but if you make sure there are words in the lease agreement/contract that address interference mitigation, you should be OK.

Considering there are a lot of these systems all across the country, I think you are pretty safe.
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Old 12-12-2017, 1:49 PM
  Audio Feed Provider
Audio Feed Provider
Join Date: Feb 2009
Location: Holly Springs, NC
Posts: 15

Thank you for the reply!
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Old 12-12-2017, 1:56 PM
902's Avatar
902 902 is offline
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Location: Downsouthsomewhere
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With the FCC's Rules transitioning to the measurement of power flux density for cellular systems, it appears that actual RF hitting the street will be significantly higher. There is already concern for 700 and 800 MHz public safety users. The FCC held a session on this recently and organizations like NPSTC are following the situation very closely.

The meter systems I'm familiar with are 902 - 928 SCADA, which are usually much lower power, but might be situationally problematic. Regardless of the frequency and power levels, mmckenna brings up many valid concerns. Make certain your roof or tower rights are clear and well-defined. Likewise for roles and responsibilities.

You might want to invest in a communications or commercial property attorney who is familiar with the services to make sure your future interests are represented and there can be no "gotchas" later on.
If you'd like to contact me, I'd be happy to speak with you off-line, but please use the email feature.
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