All You Want To Know About CATV Interference  By:  Chuck Manetta  N4YJC

Part #2: Searching For Leaking CATV Signals

With an FM Handi-Talkie or scanner receiver the audio frequencies
will seem to be distorted and over deviated , but obviously 
audio!  On either the FM or AM the video carrier will sound just 
like an unmodulated carrier.

If leakage from the cable system caused harmful interference, it 
is the responsibility of the cable operator to eliminate the 
interference, regardless of the cause. If they determine that the 
leakage is coming from a subscriber's home, they must, if 
necessary, disconnect that home until the cause of the 
interference is found and corrected.

Part 76 of The Federal Communications Commission Rules and 
Regulations, which governs the Cable Industry, clearly states:

76.613  Interference from a cable television system.

   (a)  Harmful interference is any emission, radiation
        or induction which endangers the functioning of
        a radionavigation service or of other safety
        services or seriously degrades, obstructs or
        repeatedly interrupts a radio communication service
        operating in accordance with this chapter.

   (b)  The operator of a cable television system that
        causes harmful interference shall promptly take
        appropriate measures to eliminate the harmful
        interference.

There is much more to be read out of this part of the FCC Rules 
and Regulations and can be seen at your local Field Operations 
Bureau if you are interested.

In these bulletins, I am going to focus mostly on the type of 
interference caused to the Cable Channel 18, 24, and 64-68.  The 
reason for this is two-fold.  One, is because these are the 
channels that most commonly experience fundamental overload 
interference from amateur stations, and, two, because any 
interference caused by amateur stations to these cable television 
channels is clearly not the legal responsibility of the amateur. 
Depending on the ultimate cause of the problem, it may be the 
responsibility of the cable operator, the TV manufacturer or the 
subscriber. 

Now if you are causing interference to your or your neighbors 
cable system there are many causes, suspected pieces of 
equipment, and possible cures that can be found.

But first I would like to address the situation of fielding your 
neighbors complaints.  Your average neighbor probably does not 
understand the simplest aspects of radio theory. All they know is 
that they just spent $1000 on a brand new cable television system 
and you are messing it up!  Well, it is hard to make this person 
understand that the cable company decided to put their channel 
right on top of our amateur frequency!  And quite possibly, he 
may never be able to understand.  Well there are many areas of 
the country that have local interference committees comprised of 
amateurs to help you deal with this situation.  It is a great 
advantage if possible to have a neutral third party meet with the 
offended neighbor and attempt to assist him in isolating the 
problem. This third party is most often your ARRL section 
Technical Coordinator (TC). To find your TC, contact your ARRL 
Section Manager (SM). A list of SMs appears on page 8 of any 
recent QST. 

Above all, and this cannot be stressed strongly enough, be 
polite, courteous and as civil as possible when you are dealing 
with your neighbors! This same cooperative, friendly attitude 
should be used when communicating with your local cable company. 
There are all kinds of "big" problems that can be caused by 
undiplomatically just telling someone "It's your problem!"

And there may be no practical way to cure any specific problem!  
It may be that the only possible cure is for the local cable 
company move their premium channels to another frequency.  And I 
have been told by other amateurs that this is exactly what the 
cable company in their areas have done.