[RFI] Cable TV Interference
Hare,Ed, W1RFI
w1rfi@arrl.org
Mon, 10 Dec 2001 13:48:54 -0500
Hello, Peter,
Good advice all.
I will add a couple of points. If a leak BELOW the FCC max limits causes
actual harmful interference to a radio service, the cable operator needs to
resolve the interference problem. Merely hearing a leak in our bands,
though, if it is below the max, is not harmful interference. Also, leakage
INTO the cable (ingress) is as much of a regulatory issue as leakage out --
the cable company is required to deliver a specific S/N ratio to their
customers and if ingress degrades that level, they have to correct it.
The ARRL RFI Task Group is pleased to have Ron Hranac, N0IVN, as one of its
members. Ron is a member of the Board of Directors of the Society of Cable
Telecommunications Engineers. If a ham has a problem with a cable company
and feels that the cable operator is not willing to follow the rules, Ron
can contact the cable company, usually at the senior engineering level, and
explain to them why it is important that the cable company follow the rules.
Contact rfi@arrl.org with a Readers Digest version of the attempt to work
with the cable company and it will be forwarded to Ron.
73,
Ed Hare, W1RFI
ARRL Lab
225 Main St
Newington, CT 06111
Tel: 860-594-0318
Internet: w1rfi@arrl.org
Web: http://www.arrl.org/tis
> -----Original Message-----
> From: Peter D. Vouvounas [mailto:wb3fsr@home.com]
> Sent: Monday, December 10, 2001 10:21 AM
> To: rfi@contesting.com
> Subject: [RFI] Cable TV Interference
>
>
> This message posted on-behalf of W5NA (awaiting his password)
> [REN] WB3FSR
>
>
>
>
> There have been numerous posts on this reflector concerning
> signal leakage
> from a Cable TV System some of which are not entirely
> accurate and some
> contain assumptions. Perhaps this is a good time to clarify
> the situation
> with regard to the FCC Rules.
>
> Cable TV Systems in most cases use frequencies to transmit
> their programming
> through their outside cable plant that are primarily assigned to other
> entities, some of which are primarily assigned to amateur
> radio. The Cable
> Companies are allowed to use these frequencies IF and ONLY IF
> they comply
> with the FCC Rules relative to signal leakage. Briefly a
> cable TV systems
> is suppose to be a closed loop system if properly engineered,
> installed and
> maintained and signals should be able to be distributed to
> customers so that
> they can enjoy the entertainment of cable TV and other users
> of the spectrum
> that cable is using on a secondary basis can be utilized by
> the primary
> licensed service.
>
> The FCC rules relative to signal leakage are very, very clear
> and have no
> room for ambiguity or misunderstanding by competent technical
> persons. A
> small amount of leakage is allowed but basically 20
> microvolts/meter at a
> distance of 30 feet from the leakage point is the dividing
> line. Leakage in
> excess of this amount is a violation of the FCC Rules and
> require that the
> offending cable system correct in a very timely manner.
> Failure of the
> Cable System to correct could very well lead to a citation by the FCC
> ordering that the leakage be fixed or that the frequencies
> used that are
> within the spectrum considered aeronautical could be shutoff
> until the Cable
> Operator corrects the signal leakage problem.
>
> The FCC requires that once per year and on an annual basis, each cable
> system utilizing frequencies in the aeronautical spectrum
> must certify to
> the FCC that the respective system complies with the FCC
> Rules relative to
> signal leakage. The FCC allows the cable system to certify
> by (1)a flyover
> were an aircraft equipped with suitable calibrated receiving equipment
> flyover the entire system measuring the field intensity of
> the leakage or
> (2) a rideout of the entire cable plant including the headend
> utilizing
> calibrated receiving equipment. The system simply will not
> pass if there
> are any substantial number of leaks which one would
> anticipate on a system
> not maintained properly.
>
> The cable system can develop a leak at anytime at anyplace
> and accordingly
> must be repaired in a reasonable time (few days) and CAN NOT
> wait until the
> next annual certification to perform the leak correction. In
> any good Cable
> System the service technicians have leakage detection equipment in the
> service trucks and as the technicians go about the
> performance of their
> installation and maintenance duties on a daily basis, log the
> leaks they
> detect on the signal leakage equipment as well as their
> mileage run that day
> and report them to the responsible technical person. These
> logs must be
> available for inspection at anytime by the FCC. Using this
> approach the FCC
> expects that the mileage tested in this fashion must equal or
> exceed 100% of
> the total outside plant cable mileage EVERY QUARTER of the
> year. This is in
> addition to the annual certification which is a stand alone test.
>
> Cable Systems CAN NOT hide behind an annual certification
> test on Signal
> Leakage Compliance for not repairing a signal leak in excess
> of the FCC
> allowance of 20 microvolts/meter at a distance of 30 feet.
>
> Be persistent in dealing with the technical staff of the local cable
> operator until you get results. If you don't after giving
> them a reasonable
> time to solve your problem, contact the Engineer-In-Charge of
> the nearest
> FCC Office for his assistance.
>
> Rest assured that Cable Systems would rather hear from you
> than have a pilot
> flying overhead on a large signal leak in a system which
> would break the
> squelch of his aeronautical radio/navigational equipment and report it
> directly to the FAA and FCC. That gets the cable operator a
> visit EVERYTIME
> from an FCC representative and into potential trouble and
> perhaps fines.
>
> 73,
> J. Leon Pringle, Jr W 5 N A
> E-Mail: w5na@mdxa.org
> w5na@megagate.com
> pringle50@home.com
>
>
>
>
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