W1RFI
join:2003-05-12
Burlington, CT
| reply to Middieman
Re: Current Technologies track record wrt interference
My apologies for the typo:
For the HomePlug link:
»p1k.arrl.org/~ehare/rfi/HomePlug···ARRL.pdf
HomePlug is an industry specification originally designed by an industry consortium for in-premise BPL modems. It uses OFDM (multiple carriers) between 4 and 21 MHz. Carriers in or immediately adjacent to the following spectrum have been turned off to protect sensitive reception in the licensed Amateur Radio Service:
7-7.3 MHz
10.1-10.15 MHz
14.0-14.35 MHz
18.068-18.168 MHz
At the time, the several available channels in the 5.2 MHz region did not exist for Amateur Radio.
Ed |
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Middieman
Eschew Obfuscation
join:2001-02-05
Elkins Park, PA
| Pretty interesting stuff there on Homeplug, W1RFI.
It uses the low bands, which to me is a poorly conceived idea.
And it seems that it might be detectable from a ham next door to someone with a Homeplug system if the Ham's antenna is less than 60 feet away. That could be a problem for some people. (It does not happen to affect me because I'm much further than 60 feet from other people's houses.)
However, it'd be a good idea for the ARRL to test how a ham's transmissions affect the Homeplug system. Since the device must accept interference from sources that have licensed priority (hams) then the Homeplug people might be interested in knowing that their system might be better away from ham frequencies all together... to avoid Homeplug being blown the hell out of the water by 1500 watts on the low bands.
-=[Middie]=-
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All your base are belong to DSL Reports! |
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W1RFI
join:2003-05-12
Burlington, CT | Actually, such testing has been done:
»www.arrl.org/tis/info/HTML/plc/degrade.html
Ed, W1RFI@arrl.org |
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Middieman
Eschew Obfuscation
join:2001-02-05
Elkins Park, PA
| I read the PDF of the interference study specific to the Homeplug in house module. That's just as interesting, isn't it.
It seems that a ham in front of someone's house in his/her car can completely knock out a Homeplug system with only 4 watts. (No one uses only 4 watts in a car on HF.)
Then I see later in the results section (but not how the estimate was arrived at) that BPL could be knocked off the air if their living at least within a HALF MILE of a ham radio operator. It sounds like a guess to me, based upon most hams using at least 100 watts on the low bands.
I think that the half mile radius can at least double to a mile when the power is cranked up to just 400 watts or so--a very realistic operating power for hams.
That should be disturbing to the people who make the Homeplug system.
-=[Middie]=-
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All your base are belong to DSL Reports! |
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W1RFI
join:2003-05-12
Burlington, CT
| I can add that in Cincinatti, I did a quick test with 75 watts under the same circumstances and saw no effect on the BPL system. Clearly, something was different, but we don't know what from that fast test.
I have offered repeatedly to Current and other BPL manufacturers to help with some better controlled testing, but so far, no takes. Some utilities seem more interested, but the only additional testing done was the work done in Cottonwood, AZ.
Ed |
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