Craig,
While I've not experienced this on a network I was responsible for, I
have helped a few times while at various manufacturers troubleshoot
issues like this.
Some tips in addition to what Chuck has written:
- First make sure to localize which radio it is. Some radios are
particularly nasty in these cases. Go to the site and turn off
everything, then turn on each radio individually. You may find it is a
common radio at every site, and replacing those radios with another
brand/type might be easier.
- Bad switching power supplies can sometimes be the culprit. An easy
change is to replace the power supply/PoE injector.. ideally with a
different model (instead of the vendor supplied one try maybe a McCown
Tech injector). This can be the cause of the radio or cable affecting
the repeater.
- If the interference is adjacent or a harmonic notch filters or band
filters on the 911 repeater may be an easy solution
- Double shield cable works well if the noise is from the cable and not
the radio. Shireen DC-2022 or Superior Essex BBDGE would be best
bets... and these are also easy to ground with GKCAT5 from SitePro (or
something equivalent):
https://www.sitepro1.com/store/cart.php?m=product_list&c=14. For best
effect, use every 50ft of cable run and wrap around the outside double
shield.
While these issues suck to troubleshoot... narrowing it down to the
radio causing issues is key.
Good luck Craig (hope your doing well BTW!)
<https://atheral.com/>
Daniel White
Co-Founder - Business Development & Operations
direct: +1 (702) 470-2766
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[email protected] wrote on 2/28/19 15:20:
I would first attempt to discover if it is the CAT5 or the radio itself.
Ask the 911 guys if they have a spectrum analyzer they can lend you to
puzzle this out.
Shielded CAT5 helps.
Putting in coils at the ends helps.
Ferrite chokes help.
Some run it in liquidtight or full metal conduit.
You can put fiber media converters on the ends of a CAT5 and perhaps
fix it.
But every single ethernet device, every switch, hub, router, radio
does radiate noise. Just because they passed FCC
certification tests does not mean they are noise free. The 911
repeater probably has a high gain omni and probably a super low noise
pre amplifier too. So it will naturally be more sensitive to noise
than a normal 2 way repeater.
Isolating it to a particular radio or cable is a good place to start.
-----Original Message----- From: Craig House
Sent: Thursday, February 28, 2019 1:45 PM
To: [email protected]
Subject: [AFMUG] Interference with 911 repeaters
I think I’ve posted this question on here before but I want to try
again. We have multiple water towers where we have various types of
equipment a mix of Mimosa cambium and ubiquity products. It seems
that on many of these water towers our cat five power over ethernet
creates RF interference for the repeater. In one instance we were
able to install magnets that clamped around the cable which did help
enough they stopped complaining. In other cases we’ve attempted to
move our equipment from the top of the water tower down to the
catwalk to create some distance and installed the ferrite beads with
little success at all. I’m tired of playing with ideas that might or
might not work. Can someone give me advice that will solve this
problem once and for all. I understand that grounding the CAT5 might
help I’ve also been told that putting our wires inside of conduit
might help or shortening the wires might help. I don’t want anymore
might help I would like someone who has actually done this to be able
to give me some advice
Sent from my iPhone
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