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- Newsgroups: sci.electronics
- Path: sparky!uunet!haven.umd.edu!darwin.sura.net!zaphod.mps.ohio-state.edu!swrinde!emory!athena.cs.uga.edu!aisun3.ai.uga.edu!mcovingt
- From: mcovingt@aisun3.ai.uga.edu (Michael Covington)
- Subject: Re: RF leakage from TV cable system
- Message-ID: <1992Nov9.034219.29018@athena.cs.uga.edu>
- Sender: news@athena.cs.uga.edu
- Organization: AI Programs, University of Georgia, Athens
- References: <1992Nov7.213033.163@gems.vcu.edu>
- Date: Mon, 9 Nov 1992 03:42:19 GMT
- Lines: 37
-
- In article <1992Nov7.213033.163@gems.vcu.edu> hleaves@gems.vcu.edu writes:
- >I have some questions about RF leakage from a cable TV source:
- >
- >1. Why does the cable company check for RF leakage? Is it merely to see who
- >is tapping their signal and not paying for it? Is it a health hazard? Or does
- >it cause interference to other TV's?
-
- It causes interference to other radio services. Remember that "cable
- channels," unlike real TV channels, are not allocated for TV usage outside
- the cable. For example, 155 MHz is in the middle of a cable TV channel,
- but is allocated to police radios. So if the cable signal escapes from
- the cable, the police can't hear each other. Similar things happen to
- aviation radios, hams, etc., depending on the frequency.
-
- Also, any cable leak that lets a signal leak _out_ will also let signals
- leak _in_, so that someone viewing TV suddenly hears the police or the
- fire department on top of his TV program...
-
- >2. How do they detect leakage? I'm suprised there is enough leakage from
- >a leaky system to be detectable. How much stray RF actually comes out of
- >the leaks?]
-
- Easily detectable with a radio receiver tuned to the frequency of the
- leak. I've seen cable technicians walking around with "TV sound" radios
- (cheap, the kind they sell at K-mart) scanning for leaks.
-
- Some cable leaks are audible for miles on a good receiver.
-
- >3. What is the best way to reduce RF leaks in a home cable system.
-
- Be very vigilant about not breaking the shielding -- use proper connectors
- and replace any cable that gets broken.
- --
- :- Michael A. Covington internet mcovingt@uga.cc.uga.edu
- :- Artificial Intelligence Programs phone 706 542-0358
- :- The University of Georgia fax 706 542-0349
- :- Athens, Georgia 30602-7415 U.S.A. amateur radio N4TMI
-