They don’t have a cellular extender do they?
Can you take an offending WiMax to a location with a spectrum analyzer to see
if it really may be radiating on that freq.
Also, if there is a strong transmitter nearby, you can have intermodulation
products being passively created in the WiMax. Like TV, FM broadcast etc.
Does the WiMax have an external antenna that can be disconnected to see if the
problem goes away?
Wrap the WiMax with foil and see if the problem goes away.
If it is no interference generated with the same gear at one location but
interference at another location, intermod seems likely.
You can put ferrite on the CAT5, use shielded CAT5 and put loops in it to
decouple the radio from anything in the house.
Or just power the CPE with a battery up on the rooftop to see if it still
noisy. If so, then stop looking at sources in the house.
Again, intermod, bad radio would be my two top picks.
From: Adam Moffett
Sent: Monday, January 23, 2017 8:49 PM
To: af@afmug.com
Subject: Re: [AFMUG] Weird cellular interference issue
Not shielded cable, but still a good idea.
This person doesn't have HAM equipment, but I'm thinking something along the
same lines. Maybe a device in the house is inserting this signal on the
neutral or ground wire of the A/C. Maybe A/C ground is bonded to D/C ground in
the PoE. Maybe D/C ground is bonded to a ground plane in the panel antenna.
Lots of maybes there. Maybe I'm talking out of my hole.
------ Original Message ------
From: "George Skorup" <geo...@cbcast.com>
To: af@afmug.com
Sent: 1/23/2017 10:39:18 PM
Subject: Re: [AFMUG] Weird cellular interference issue
Is it shielded cable? Sounds like the shield has become a radiator, aka
antenna. Detune it by adding or removing some cable length?
On 1/23/2017 9:32 PM, That One Guy /sarcasm wrote:
place the poe in a faraday cage, it will resolve it, we have a HAM guy that
has something in 800mhz, same issue, suggested he do that, it resolved it, he
didnt describe what cage he built
On Mon, Jan 23, 2017 at 9:24 PM, Adam Moffett <dmmoff...@gmail.com> wrote:
This is above my pay grade.
One of our customers was contacted by AT&T, and the customer put them in
touch with us. AT&T was tracking down a source of interference. The
interference was on a 10mhz wide channel centered on 828mhz. At their tower,
AT&T is seeing it 15-20db above the noise floor, so it's pretty significant.
Using their spectrum analyzer they tracked it down to our customer's
house. The customer has a wimax CPE on their roof. Unplugging the CPE makes
the interference go away, plugging it back in brings the interference back.
Every time. AT&T guy goes to another customer's house and confirms that other
CPE at different locations don't produce this interference.
We figure it's a malfunction in the CPE, so we replace it. Interference
still present.
We replaced the PoE. Interference still present.
So we know the Wimax unit doesn't originate the 828mhz signal, but it's
somehow an accidental component of a system that does.
WTF could be going on?
--
If you only see yourself as part of the team but you don't see your team as
part of yourself you have already failed as part of the team.
