On 12/7/2013 8:13 AM, Alan NV8A wrote:
Especially when people have messed with (extended, rerouted, spliced)
the coax in their homes and left everything leaking like a sieve,
There are many cases of TV antennas hard wired to the TV set along with
the cable, making the TV antenna a strong radiator of these signals,
In many cases there is a preamp, no longer powered in the circuit that
will rectify ham signals that the antenna re radiates as well as feeding
them into the cable system.
Several decades ago I lived in a town where most of the system suffered
from both ingress and egress. Fortunately I was able to demonstrate at
the office, which was also the location for the head end amplifier.
With a 5W HT, I could shut the cable system for the entire town, down.
As we were about 20 miles from the repeater, most mobiles ran 25 to 50
watts. I demonstrated that could shut the system down from over a block
The next evening, after work, most of the town was cleaned up, the next
evening I could find no leakage.
On 12/06/13 07:14 pm, W5JR.Mike wrote:
This is the great "TV White Spaces" project. Once the channels above
21 are repurposed for more wireless broadband (known as "600 MHz"
despite including a large chunk of 500 MHz) save for channel 37
(astronomical use) and channels in the "duplex gap", and the remaining
UHF TV is "repacked" into channels 14-21 (and some upper VHF, 7-13),
there likely won't be much, if any, "White Space" left.
And again, the traditional cable TV plant, while using DTV like
signaling, still utilizes the same channel assignments as over the air
broadcasts. So, more interaction between a wireless phone/tablet and a
cable system is on the horizon.
Mike / W5JR
On Dec 6, 2013, at 4:26 PM, "EDWARDS, EDDIE J"<email@example.com>
Speaking of cable TV systems, which is one of our main power line
interference customers in town...
I attended an IEEE meeting this week with a presentation on
"Multicasting in Cognitive Radio Networks" by a PHD college professor
from Iowa. It was very good and pretty technical, and nearly over my
head, but the presenter was basically describing a very efficient
wireless mesh type data network system that would use the unused
portions of the TV spectrum (since it would probably be unlicensed
When I asked if RF Interference issues were analyzed since there
would be possible RFI to and/or from power lines and cable TV
systems. He gave me a deer-in-the-headlights look and said no such
analysis had been done. After the presentation, he approached me
with some questions about possible RF interference, and he seemed
amazed there could be such interference. It clearly had not occurred
73, de ed -K0iL
From: RFI [mailto:firstname.lastname@example.org] On Behalf Of W5JR.Mike
Sent: Thursday, December 05, 2013 10:09 PM
To: Anthony (N2KI)
Subject: Re: [RFI] RFI in the news
Traditional cable TV systems use the same spectrum above 470 MHz that
over the air broadcast uses. And they are still using the spectrum
between channels 52 and 69 that has been repurposed for Land Mobile,
Public Safety and cellular. And the issue goes both ways. Leakage
from cable plants are heard by 700 and 800 MHz base stations.
Mike / W5JR
On Dec 5, 2013, at 1:05 PM, "Anthony (N2KI)"<email@example.com>
This also happens with Direct TV C31-700 box. FYI
On Thu, Dec 5, 2013 at 12:48 PM, Charles
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