91439306
15,000 Watts of Bass Power
join:2002-10-16
New Milford, CT
| reply to rf_engineer
Re: You've got to be kidding me
I hung a 1/4-wave shunt across the 300 ohm terminals of the Sansui, and that brought in at least the 5 big CT stations, but I find it unreasonable that a 50,000 watt FM with a tall E-plane pattern is allowed in a residential neighborhood. We didn't have this problem when they used 6 bays of Dialectric antennas. But now that they increased power and decrease to two bays of ERI antennas, we have a 20X increase in ground level field strength.
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Take care,
Mark & Mary Ann Weiss
Hear my Kurzweil Creations at: »www.dv-clips.com/theater.htm
Business sites at:
'»www.dv-clips.com
'»www.mwcomms.com
'»www.adventuresinanimemusic.com
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rf_engineer
join:2003-08-04
USA
1 edit | reply to 91439306
said by 91439306  :
It is called 'blanketing' interference and radio receivers have to accept it.
It wipes out the ENTIRE FM dial up here, on my Jensen car stereo, and most of the dial on the wife's Sansui. Forget about using a portable or clock radio. 100% obliteration.
Realize, though, that it's not necessarily the fault of the radio station. Every receiver contains a filter in the "front end", the first part of the receiver that gets the signal from the antenna. The job of this filter is to attenuate signals that we aren't interested in receiving. A perfect filter would infinitely attenuate unwanted signals. In the real world, though, a front end filter attenuates the unwanted signals a large amount, but some of the unwanted signal gets through the filter. Taken to the extreme, when you have a powerful transmitter next to a receiver, a large amount of unwanted signal will get through. This unwanted signal gets to subsequent stages and gets detected and converted to audio.
Better receivers have better filters and will be able to tolerate strong signals, especially ones that are adjacent or close by your intended receive frequency. One could also put a "notch filter" ( »www.scott-inc.com/html/fmnotch.htm ) in front of the receiver to add additional attenuation to the unwanted signal.
quote:
Not a damned thing anyone can do about it.
Actually, FM stations are required to help resolve blanketing issues in some situations »www.current.org/pb405.html and »www.scott-inc.com/html/73318.htm ...
( Update: Ooops, I didn't see the dates in your post. Buy a notch filter  ) |
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91439306
15,000 Watts of Bass Power
join:2002-10-16
New Milford, CT
| reply to TheMadSwede
I live within the fall zone of a 50,000-watt FM tower, and ya know what? Not a damned thing anyone can do about it. They were here since 1959 and the houses came in the 1960s.
It is called 'blanketing' interference and radio receivers have to accept it.
It wipes out the ENTIRE FM dial up here, on my Jensen car stereo, and most of the dial on the wife's Sansui. Forget about using a portable or clock radio. 100% obliteration.
Not a damned thing anyone can do about it.
--
Take care,
Mark & Mary Ann Weiss
Hear my Kurzweil Creations at: »www.dv-clips.com/theater.htm
Business sites at:
'»www.dv-clips.com
'»www.mwcomms.com
'»www.adventuresinanimemusic.com
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rf_engineer
join:2003-08-04
USA
| reply to TheMadSwede
said by TheMadSwede :
I hate to turn this into an "interference annoyance" forum, but I live less than a mile from an FM tower for a local station and it jacks with at least 2 other stations that I enjoy.
It may be an issue with your receiver. A lot of pieces of consumer equipment can't deal with strong signals nearby, especially if they fall on the right frequency (aka the "IF image frequency") or are adjacent to a distant station you're trying to receive. So this may not be the fault of the local FM station. You should probably start by talking to the chief engineer of the station and give specifics. They don't like FCC compliants and should be willing to help or at least figure out what's really going on. |
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N0JCG
join:2003-07-18
Minneapolis, MN | reply to TheMadSwede
Have you filed a complaint? |
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TheMadSwede
Premium
join:2001-01-30
Holland, MI
 ·Charter Pipeline
| reply to 91439306
I hate to turn this into an "interference annoyance" forum, but I live less than a mile from an FM tower for a local station and it jacks with at least 2 other stations that I enjoy.
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Hey - there's this thing called spell check... |
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91439306
15,000 Watts of Bass Power
join:2002-10-16
New Milford, CT
| reply to W1RFI
said by W1RFI :
The interference you describe from power lines is not legally acceptable. The FCC has written advisory notices to over 30 power companies to date, requiring that they correct the harmful interference from their power lines.
ARRL has a cooperative agreement with the FCC to try to resolve these cases directly with the power companies, but after those reasonable efforts fail, the FCC is willing to start waving the stick.
See:
»www.arrl.org/tis/info/part15.html
for information about the FCC Part 15 regulations.
Ed Hare, W1RFI
ARRL Laboratory Manager
I would like to see them correct the severe RFI from the new traffic signal lights (LED) used in CT now. When I'm 1/4 mile or less from one of those things, it buzzes louder than the audio of the AM station I'm trying to hear.
Who the heck approved these solid state traffic lights without RFI testing first? They would have put in filtering had they bothered to test them before deploying thousands around here.
--
Take care,
Mark & Mary Ann Weiss
Hear my Kurzweil Creations at: »www.dv-clips.com/theater.htm
Business sites at:
'»www.dv-clips.com
'»www.mwcomms.com
'»www.adventuresinanimemusic.com
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W1RFI
join:2003-05-12
Burlington, CT
| reply to TACSPEED
The interference you describe from power lines is not legally acceptable. The FCC has written advisory notices to over 30 power companies to date, requiring that they correct the harmful interference from their power lines.
ARRL has a cooperative agreement with the FCC to try to resolve these cases directly with the power companies, but after those reasonable efforts fail, the FCC is willing to start waving the stick.
See:
»www.arrl.org/tis/info/part15.html
for information about the FCC Part 15 regulations.
Ed Hare, W1RFI
ARRL Laboratory Manager |
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N0JCG
join:2003-07-18
Minneapolis, MN | reply to TACSPEED
Actually, you could file a complaint with the utility and the FCC about the interference from the power line. |
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TACSPEED
Premium
join:2001-04-14
Tacoma, WA
·Advanced Stream
| reply to N0JCG
quote:
The FCC part 15 emission level is only a guide. No unlicensed device can cause harmfull interference, regardless of emission level.
There's obviously more to it. Since when I drive my car under a high voltage power line I get interference with my AM radio reception. Unless you are saying that power lines are licensed devices. In which case, interference caused by PLC is legally acceptable.
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Fiber Optics is the future of high-speed internet access. Stop by the BBR Fiber Optic Forum. |
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N0JCG
join:2003-07-18
Minneapolis, MN | reply to TACSPEED
The FCC part 15 emission level is only a guide. No unlicensed device can cause harmfull interference, regardless of emission level. |
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TACSPEED
Premium
join:2001-04-14
Tacoma, WA
·Advanced Stream
| reply to Transmaster
Does the emission level due to PLC using OFDM exceed FCC regulations?
Do FRS radios and cell phones raise the base noise level?
We wouldn't want breaker, breaker Bob's CB or the kids walkie talkies to interfere with that emergency call.
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Fiber Optics is the future of high-speed internet access. Stop by the BBR Fiber Optic Forum. |
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