parnass@ihu1h.UUCP (Bob Parnass, AJ9S) (10/23/84)
Leaky CATV Equipment Interferes With Scanner User
A non-ham scanner friend from Westmont (Illinois) related
this tale of grief caused by CATV signals (he is not a CATV
subscriber):
"In August 1984, a storm dropped several heavy bran-
ches onto the cable trunk line in my alley. New York
channel 9 appeared on my channel 4. The UHF Atlanta
superstation came in on channel 13. Manipulating the
tuner controls on my (35 channel) cable ready VCR
brought in HBO, Showtime, Cable News Network and other
cable services with varying levels of snow and inter-
mod. Worse yet, regular Chicago stations now had a
ghost caused by the cable retransmission being
microwaved around first thus being rebroadcast mil-
liseconds behind the direct receptions. Finally, my
scanner was being jammed all over the spectrum."
"A call to the FCC brought a 'don't disturb my bureau-
cratic games, what do you want me to do, be a public
servant?' attitude. I called the FAA as they have a
remote control sight at nearby Downers Grove/Woodridge
in case their system was getting interference. A call
to the local cable company office confirmed my suspi-
cion that employees were never trained about a closed
circuit 'broadcasting'. Besides, a service call was
rejected by their computer because I was not a subscri-
ber."
"I located the regional cable company office in a city
it did not serve. From their operator, I found out the
name of the Chief Engineer who did not return my call.
I sent a certified letter to him citing chapter and
paragraph of the FCC regulations. I established my
right as a user of the electromagnetic spectrum as a
broadcast watcher (scanner owners have no rights as
they are not the intended recipient normally) that
could not watch non-local stations anymore as well as
having regular channels ghosted....... That
[registered letter] brought results, a call from the
Construction and Repair Chief besides the Chief
Engineer."
"I had prepared for this by walking several blocks in
all directions with a portable scanner to find the
point of highest signal strength. The cable company's
sweeps were inconclusive because they used a wide band
measuring device. Thus, they measured up to 6 MHz of a
public safety/business band spectrum. About 100 police
and fire departments and 1000 business users masked any
meaningful meter reading. After replacing first the
connectors, then the 4-drop couple and finally a 500
foot section of trunk cable, the interference cleared
up."
"A nearby ham continued to suffer interference
however. He is a subscriber" and "had added a section
of coaxial cable to the cable connecting his TV set
with his VCR. That cable purchased at a handy neigh-
borhood national electronics chain store.....did not
have a 100% shield...." [so it allowed CATV signals to
radiate around his own house].
--
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Bob Parnass, Bell Telephone Laboratories - ihnp4!ihu1h!parnass - (312)979-5414 karn@mouton.UUCP (10/23/84)
Regarding leaky CATV systems...I have an item which should appear in QST Hints & Kinks soon about a way of locating it. A 2-meter SSB receiver is about the most sensitive device I know of for detecting CATV leakage. I also found that the doppler shift caused by vehicle motion is quite readily apparent on a mobile SSB transceiver as you drive past the offending spot. Finally! A practical use for all that Relativity Physics you learned in school. Phil