Radio interference from my comcast lines?

Factual Questions
1

Ok, I know just enough about electronics to be dangerous. I’m a computer guy, but not really an expert in advanced radio phenomenon but what comcast is telling me sounds like cow excretions.

A pair of comcast feild techs came into my mom’s yard this morning, disconnected the service drop at the pole, then removed a splitter on the back wall of the house. No warning, no communication, no courtesy notice on the door.

Sister was present, she confronts them, they scurry off and refuse to talk to her.

The reason they give when mom calls…

That interference generated in our household cable tv/internet wiring was so dramatic/powerful that it was creating interference with with radio communications between the tower and aircraft the Fresno Airport 3 miles away.

Granted:
I know shorts in electrical equipment can create RF phenomenon, I was however under the impression that this was very limited in range.

Other relevant information
The problem was allegedly a bad section of cable about 15 feet long replaced it, “problem” went away.

This was inside a stucco walled residential home.

The comcast cable and Internet service seemed perfectly functional to us prior to the disconnection this morning.

My thoughts:
I could see a short in our wiring creating enough noise on the lines that nearby cable customers might be affected, even be a measurable shift in line impedance or SnR at the nearest comcast network operations center.

But generating enough RF output to mess with the local airport? And that some kind of “authorities” demanded that comcast solve the problem? How would the “authorities” know it was a comcast customer as opposed to a malfunctioning ham radio or someone with similar equipment being an idiot?

I can see airports having tech types who are more than capable of using a radio direction finder to hunt down the source of rogue radio interference, but why wouldn’t they knock on the door if that was the case.

The feild tech that came out to fix it stood by the story given when my mom called in. I went over to be present because I am a more “techy” critter than the rest of my family.

So, I know we have some EE’s and very radio savvy folks, thoughts?

2

It’s an odd story, but as far as the techs going into your backyard, no they don’t need your permission. They have an easement from the pole to wherever it connects to your house and X feet on either side of it as well as access to and from it from the street, for exactly this reason. They need to be able to access it whether or not you’re home.
If any utility lines cross through the yard, there’s easements for those as well.
I believe if you had a locked fence or loose pets in the yard and you weren’t answering your door they may have to give you a notice but IIRC as long as they can get to and from the line safely they can have at it.

Look at it this way, if your cable was out and they had to do something in the neighbor’s yard, how long would you be willing to wait if the neighbor wasn’t home?

The utility companies need to be able to get at the lines to maintain them without requesting permission from hundreds of people every day.

3

I understand the easement thing, they did circumvent a locked gate, you can lean on the post it’s latched to and disengage it if you are determined. I’m not really concerned about the yard access, i know they can do that, in my experience they at least try to say hello and “hey, we need to do some work on the lines back here” so they don’t startle anyone. The second tech said that it was SOP to at least try and notify the homeowner if they needed access to the yard.

More puzzled by the “radio interference” story. Seems like a really odd thing to lie about, and something that we would see interruptions of service or poor cell phone reception/wifi perfomance from the raw amount of signal bleed if it’s being picked up miles away.

4

It sounds like they’re talking about a signal leak. The FCC’s page on cable leaks specifically mentions air traffic communications as a potential problem, so that part has happened before.

5

Ok, that makes a certain amount of sense, did not realize that they were using broadcast frequencies inside coax.

Upon googling signal leak it makes alot more sense now. I can understand how such interferece could occurr but I am still having a hard time imagining moms internal house wiring was creating such a dramatic problem. Generating leakage sufficient to rate a prompt repair, sure. But a zero notice disconnect with no explanation or attempt to contact the customer feels … weird.

The tech that fixed it looked like he was was just checking SnR on the line. No mention of the words “signal leak” or any other, detection tools mentioned/utilized. As a computer guy I have encountered lots of comcast feild techs, first I have ever heard of this is today.

6

I don’t see how that could happen, 3 mi from the airport. The signal level in the coax is microvolts. It is NOT a transmit line carrying 100 or 1000 watts of RF power. There is so little RF energy in that line it requires very sensitive low-noise amplifiers in the cable TV box to pick that up.

Any leaked RF energy of those microvolts would diminish with distance according to the inverse square law. This states that RF energy in microvolts per meter is inversely proportional to the square of the distance from a source. If it were leaking TV signal RF energy, to even pick that up usually requires someone with a hand-held Yagi antenna and spectrum analyzer standing in front of your house, with the directional antenna aimed at your house.

Now, if the coax was improperly shielded or terminated, then it could pick up household interference which might then cascade down the line using the braid of the coax as a radiating antenna. But this wouldn’t be cable TV signals leaking out but the coax allowing higher-power interference IN to enter the line and re-radiate.

7

The info you are giving us, as you did not see this first-hand, it’s hard to decipher the WWWWWH.

My WAG is that you have some other device in the house, like a cable amplifier, which was noisy and causing issues for your neighbors. Could that noisy amp cause issues 3 mi down? Possibly, if it was connected in reverse. I actually had to deal with that at a job I used to have. The incoming cable was just lousy and we B&M’d for ages and finally they looked into. It was someone who had split cable from a neighbor and put in a cable amp, but connected it backwards, which was spewing noise down the line. The split was in a residential are and we were in a business park a few miles down.

Or, someone put that splitter in and had an extra TV or device using the cable service which was unpaid for. You pay per connected unit usually, and, yes, even with something as simple as a TLDR and if you know how to use it, you can enumerate the end points readily. Since the utilities don’t want to be seen as the bad guy, they’ll usually go back and forth a bunch of times disconnecting things to be as annoying as possible, throw the TOS at you and maybe even ban you from service, before going to court.