Good summary - just a small leakage limit correction is in order:
Frequency less than or equal to 54 MHz and greater than 216 MHz, the limit
is 15 microvolts/meter at 30 meters (100 feet), and between these two
frequencies it is 20 microvolts/meter at 3 meters (10 feet); i.e., between
54 and 216 MHz (where the aeronautical band resides), the requirement is 7.5
times more stringent than outside that frequency range.
Jim, WA7SLD
-----Original Message-----
From: Peter D. Vouvounas [mailto:wb3fsr@home.com]
Sent: Monday, December 10, 2001 8:21 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
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|