TACSPEED
Premium
join:2001-04-14
Tacoma, WA
 ·Advanced Stream
| reply to RoguePimp
Re: You've got to be kidding me
quote:
hey are joking right? Who does not have a complaint about BPL? There must be a way to work out the issues at hand
It looks like they are working on the interference issue.
From ISOC
Electro-Magnetic Radiation Issues
Earlier PLC systems such as the one developed by Nor.Web in the UK emitted a high level of radio noise in the 1-30 MHz bandwidth. This resulted in conflicts with the British government's Radio Agency, when it disrupted radio signals from the BBC World Service. The Department of Trade and Industry (UK) subsequently made it impossible to use PLC in the UK and contributed to the withdrawal of Nor.Web from the business.
Learning from the failures of Nor.Web approach, second generation PLC technologies are using techniques like OFDM, which substantially reduce the potential of interference to radio users, thanks to a decrease in transmitted power spectral density. The OFDM modulation spreads the signal over a very wide bandwidth, thus reducing the amount on power injected at a single frequency. Field trials of PLC technologies carried out during the last 2 years in Europe (Spain, Italy, Germany), North America, South America (Chile, Brazil) and Asia (Singapore) have shown that interference with radio users is no longer a problem for PLC.
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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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n2jtx
join:2001-01-13
Glen Head, NY
·Optimum Online
|  said by TACSPEED  :
Learning from the failures of Nor.Web approach, second generation PLC technologies are using techniques like OFDM, which substantially reduce the potential of interference to radio users, thanks to a decrease in transmitted power spectral density. The OFDM modulation spreads the signal over a very wide bandwidth, thus reducing the amount on power injected at a single frequency. Field trials of PLC technologies carried out during the last 2 years in Europe (Spain, Italy, Germany), North America, South America (Chile, Brazil) and Asia (Singapore) have shown that interference with radio users is no longer a problem for PLC.
In other words, rather than pollute just a few frequencies, we spread the noise across the entire spectrum thus raising the noise floor for everyone. Forget it. So far the only BPL system that looks good is the 5GHz system. |
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Transmaster
Don't Blame Me I Voted For Bill and Opus
join:2001-06-20
Cheyenne, WY
 ·Qwest.net
| reply to TACSPEED
said by TACSPEED :
All this does is raise the base noise level all across the spectrum. If you want a example listen to a shortwave broadcast in a city, then drive to the country and listen
again the difference in the over all noise is really surprising. So if you are on an FRS radio, or a cell phone this increase in the base noise level might mean the difference between being heard and not. This is really true for digital cell phones where you are either all there or not at all. It would be a hell of a note to not be able to get help in an emergency because a local LAN party was honking away on flaming Dragons of the outer wa-zoo over the area BPL system.
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TACSPEED
Premium
join:2001-04-14
Tacoma, WA
·Advanced Stream
| 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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N0JCG
join:2003-07-18
Minneapolis, MN | 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
| 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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N0JCG
join:2003-07-18
Minneapolis, MN | Actually, you could file a complaint with the utility and the FCC about the interference from the power line. |
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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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91439306
15,000 Watts of Bass Power
join:2002-10-16
New Milford, CT
| 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.
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Take care,
Mark & Mary Ann Weiss
Hear my Kurzweil Creations at: »www.dv-clips.com/theater.htm
Business sites at:
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'»www.mwcomms.com
'»www.adventuresinanimemusic.com
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TheMadSwede
Premium
join:2001-01-30
Holland, MI
·Charter Pipeline
| 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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N0JCG
join:2003-07-18
Minneapolis, MN | Have you filed a complaint? |
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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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W1RFI
join:2003-05-12
Burlington, CT
| reply to TACSPEED
> Learning from the failures of Nor.Web approach, second
> generation PLC technologies are using techniques like
> OFDM, which substantially reduce the potential of
> interference to radio users, thanks to a decrease in
> transmitted power spectral density.
OFDM does not decrease the transmitted power spectral density. It takes a certain amount of spectrum to transmit a certain data rate at any specific signal to noise ratio. In the US, the OFDM BPL systems operate at the FCC Part 15 radiated-emissions limits of 30 uV/m at 30 meters, just like other BPL systems.
Go to the ARRL video at »www.arrl.org/tis/info/HTML/plc#video and look at trial area #4, the Ambient BPL system in Briarcliff Manor, NY. It is an OFDM system based on the DS-2 chipset. That will demonstrate quite well that OFDM does not reduce the inteference potential. 30 uV/m is 30 uV/m is 30 uV/m when it comes to interference and the simple laws of antenna physics predict what signal levels will be received on nearby antennas.
Ed Hare, W1RFI
ARRL Lab |
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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
1 edit | 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
| 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.
--
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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