[RFI] RE: Concerning BPL video

[Hare,Ed, W1RFI]

> Well, it's obvious from the BPL video that BPL is indeed needed. I say
> this because of the bandwidth that is used up by all the unjustified
> negative publicity concerning BPL. After listening to the 
> audio several
> times, I hear nothing that sounds like BPL. I'm a little 
> confused. 

Then I have to wonder what you may have heard that you thought was BPL, Mike.  The signals recorded in test area #1 were recorded while the involved amateur's BPL modem was downloading a streaming video. When it stopped downloading, the noise went away. There is no 60- or 120-Hz component, so it is not power-line sparking, and no power-line spark I know does that kind of popping.

In trial area #3, the sound being heard is the "keep-alive" pulses of a number of modems talking to each other, along with the occasional longer burst. I found this noise only in areas where the overhead power lines had BPL couplers, and outside those areas, we heard only the occasional normal power-line noise.  That system is a direct-sequence, spread-spectrum system. Again, there is no 60- or 120-Hz component.

In test area #4, the BPL system is another OFDM system, quite a bit different than the others. There is no doubt at all that those birdies heard every kHz or so are from the BPL system, because again, the signal drops off outside the test area. The involved BPL manufacturer also notes that those are their signals, so that one is a bit hard to explain away.

> Why? When I'm testing for BPL emissions, I can hear it while my 
> antenna is 20  feet from the source. However, when I drive away the signal is gone.

If the signal is inaudible 21 feet from the source, it is being radiated at much less than the FCC limits. If so, why is the industry asking that the limits be raised if their systems work right now well below those limits?  Perhaps this is good evidence that the FCC limits for BPL should be lowered?

> The questions I'm asking above are not because I'm looking 
> for answers. They are questions you should ask yourself. 
> I think I already know the answers.

Want to meet me in test areas #3 and 4 later this week? :-)  I have been to 4 test areas and I think I already know the answers, too. What is shown on that video is an accurate represenation of what was found in each of the systems.  

73, 
Ed Hare, W1RFI
ARRL Lab
225 Main St
Newington, CT 06111
Tel: 860-594-0318
Internet: w1rfi at arrl.org
Web: http://www.arrl.org/tis

> -----Original Message-----
> From: Mike @ RFI Services [mailto:mike at rfiservices.com]
> Sent: Saturday, August 09, 2003 12:20 PM
> To: rfi at contesting.com
> Subject: [RFI] RE: Concerning BPL video
> 
> 
> Well, it's obvious from the BPL video that BPL is indeed needed. I say
> this because of the bandwidth that is used up by all the unjustified
> negative publicity concerning BPL. After listening to the 
> audio several
> times, I hear nothing that sounds like BPL. I'm a little 
> confused. Maybe
> I down loaded the results of and interference complaint caused by a
> combination of power line sparking and several narrow band 
> inside noise
> sources. I'll listen again.
> Question:
> Has anyone ever heard of a complaint filed by a ham that is 
> experiencing
> RI from BPL? I have. The source was a touch control lamp 2 
> blocks away.
> With an active BPL system in the QTH.
> I'm in the business of locating the sources of RFI, regardless of the
> cause(s). So if BPL were a problem, it could be seen as another source
> of job security for me. However, to this date I haven't heard 
> of another
> complaint made by a ham claiming to have problems from BPL. Why?
> Has anyone else seen a complaint that the cause was found to be BPL? 
> Of all the concerns we read about on reflectors, why are they all
> responses to the concerns and never about a known problem? Surely
> someone would have had one by now. These test systems are in 
> areas that
> know one even knows about. Still no complaints. After everyone is
> notified that the system is under test and it is offered, still no
> complaints. Why?
> When I'm testing for BPL emissions, I can hear it while my 
> antenna is 20
> feet from the source. However, when I drive away the signal is gone.
> Why don't we put this much energy into stricter enforcement concerning
> Dimmers, touch control lamps, doorbell transformers, aquarium heaters,
> power supplies, TV sets and telephones. This would be a real 
> challenge.
> I investigate over 500 RFI complaints per year and over 60% 
> of them are
> the sources listed above. Their are more but they are the 
> most frequent.
> Power line carrier systems have been in houses and on power lines for
> the entire 25 years I've been involved in RFI. I can count the
> complaints concerning them on one hand. Those systems didn't 
> bypass the
> ham bands as do the new systems.
> The questions I'm asking above are not because I'm looking 
> for answers.
> They are questions you should ask yourself. 
> I think I already know the answers.> Very sincerely Best wishes,
> Mike Martin
> RFI Services
> 6469 Old Solomons Island Rd
> Tracy's Landing MD 20779
> 301-855-5961 Tel (E.S.T.)
> 410-741-5153 Fax
> 164*21*29180 Nextel
> mike at rfiservices.com
> www.rfiservices.com
> 
> 
> 
> 
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