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sporkme
drop the crantini and move it, sister
Premium,MVM
join:2000-07-01
Morristown, NJ
 ·Optimum Online
| reply to drjim
Re: FCC Official Anouncement
said by drjim  :Yes, but the ARRL has a Motorola system, and Motherola understands radio *far* better than these fly-by-night outfits. And doesn't Motorola's system use wi-fi-like radio for the "last mile"? | |
rf_engineer
join:2003-08-04
USA
| reply to Anon
Re: DS2 200 Mbps BPL tech is working with ARRL Laboratory !!!
said by BPL 200 Mbps :Hope this will give light to the matter. Congratulations on making a post that promotes your favorite chipset manufacturer and at the same time is on topic, all while using only nine exclamation points, not counting your sig line.  You've come a long way since your anonymous days »Earthlink uses Ambient BPL modems
Note that the system in operation at ARRL HQ is Homeplug based, not DS2, but DS2 did meet with ARRL. I haven't heard anything since; are they still working together? It would be nice to see a DS2 based system operating at ARRL HQ. Considering that there's several manufacturers using DS2 chips, I wonder why there isn't one of those systems operating there for testing. | |
BPL 200 Mbps
join:2006-11-05
Toms River, NJ | "I wonder why there isn't one of those systems operating there for testing."
You knew the answer, Mr. hamster !!!!
No body except DS2.es ...IMHO | |
rf_engineer
join:2003-08-04
USA | Actually I don't know the answer, otherwise I wouldn't have asked the question. The ARRL HQ site would be good for ingress interference testing as well. They run about six high power transmitters five days a week. | |
BPL 200 Mbps
join:2006-11-05
Toms River, NJ
| re: "DS2 provides a special mitigation technique called "Notching" which ensures that no interfering radio signals are produced at the critical frequencies used by short-wave radio. Notching has been a key requirement of recent rulings from both the FCC and the European Union. The flexibility of the DS2 product, with its programmable spectrum mask and downstream notching capability has been tested by the British Telecommunications regulator (www.ofcom.com) and has been praised in a published Ofcom report as a " a significant step towards a more EMC friendly PLT solution."
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Unleash the opportunities of a SYMMETRICAL 200Mbps “Smart Grid”, IPTV and in-home networking for business optimisation of your commercial opportunities of BPL/PLC with killer applications & services: in-home MDU networking, IPTV and triple-play... !!! | |
W1RFI
join:2003-05-12
Burlington, CT
| reply to rf_engineer
The Motorola system at ARRL HQ was also tested for ingress. The system had been installed at W1AW, the bulletin station at ARRL HQ in Newington, CT. The station operates simultaneously on 7 bands in the frequency range BPL uses, at a power level of 1500 watts on each band. The BPL system was installed in a test configuration with the wireless link shooting across the parking lot from the ARRL HQ administrative building to the W1AW building located about 300 feet distant. The bulletin-station antennas are clustered around the building, with the closest being the 3.5 MHz dipole that is about 20 feet over the building.
A 240-volt wire was run to one of the W1AW towers, to simulate a typical drop wire from an overhead pole to a premise. The Motorola BPL system was operated on the 120-volt wiring inside W1AW. Most of the building uses conduit, so separate plastic-sheathed "Romex" style wiring was run from the demark point to locations on the first and second floors of the building.
I was testing the sytsem with the Motorola engineer at the time the bulletins came on. The system data rate was not significantly slowed down from on/off-keyed CW, single-sideband or data transmissions. My conclusion was that the hardware filters provided significant rejection of nearby radiated signals.
Ed Hare
ARRL Laboratory Manager
225 Main St
Newington, CT 06111
Tel: 860-594-0318
Email: W1RFI@arrl.org
| |
W1RFI
join:2003-05-12
Burlington, CT
| reply to rf_engineer
>> You knew the answer, Mr. hamster !!!!
> Actually I don't know the answer, otherwise I wouldn't have asked the question.
It would be interesting to see if BPL200mbs is willing to share what answer he thinks you knew. (I am not sure why he is choosing a screen name that says that BPL operates at 200 millibits per second, though.)
From the onset, ARRL has left the doors to cooperation wide open. Motorola led the way in taking advantage of the opportunity, but at this later date, some of the other BPL manufacturers, utilities and ISPs are also ready to do what needs to be done to what needs to be done to improve the electromagnetic-compatibility (EMC) performance of BPL.
Those doors were open before access BPL came down the pike. ARRL's work with HomePlug helped them to design a product that has deployed without major interference problems. Their product specification includes notches in all of the ham bands. To date, there are 6,000,000 HomePlug devices deployed, and ARRL doesn't have a single reported case of interference involving HomePlug and Amateur Radio. Frankly, why the rest of the access BPL industry actively avoids any formal specifications for their product to do the same thing is puzzling at best. I have tried to persuade the IEEE P1775 BPL EMC committee to do so, to no avail.
To date, the most successful BPL company has been Current Communications, with BPL deployed past 60,000 homes in Cincinnati and in progress past 2,000,000 homes in Dallas. Their product uses HomePlug specifications, and not surprisingly, they have not had major interference problems. They also maintain regular dialogue with ARRL. It is ironic to me that with all the fuss that some in this industry have gone through to avoid having to address interference responsibly, the most successful BPL company is building on work that ARRL helped do. See:
»p1k.arrl.org/~ehare/rfi/HomePlug···ARRL.pdf
Other companies are also cooperating. I have regular conversations about EMC issues with Amperion, Current, IBEC, Mitsubishi, and Corinex. These companies are serious about EMC and sincerely want to see their products deploy successfully without interference problems. They are the ones that have positioned themselves to best be able to do that.
I also maintain ongoing dialogue with the electric utility industry. It is always interesting to note that after the IEEE meetings, I am most often dining with guys from the power industry, asking and answering questions. (Most of these utilities are hungry for information, and they know that I will tell them things that the BPL sales folks probably won't.)
Other companies are not as cooperative. In once case, I ran into engineers from one of the companies at one of the BPL sites. Their responses to interference complaints there claimed they wanted to cooperate, but when I invited the engineer to take a quick ride in my mobile station to see firsthand what interference I was seeing, he told me that he couldn't do that. That company's idea of cooperation didn't include taking a 10-minute ride in my car.
BPL200mbs is correct in one of the claims he is making about his investment, though -- DS2 has made incremental improvements in their notching. At about -40 dB, both the work done in the ARRL Lab with their engineers and my own experiences in the field show a significant improvement in the interference potential *to Amateur Radio." At the Corinex installation in Houston, I found that most of the system was operating legally and that except in the two areas where I saw the system operating over the FCC limits, the notching was adequate to be a reasonable general EMC solution. A fixed station there had filed an interference complaint, and CenterPoint did what was needed to correct the interference. When I visited that station, I confirmed that the interference was fixed.
What this shows is that if BPL avoids locally used spectrum, it will not interfere with frequencies it doesn't use. That, however, needs to be much better than the early deployments of BPL, that had 25 dB of notching on a good day. Some in the industry have quietly confessed to me that their early systems had problems. I appreciate the improvements, but I also note that they are not going to take back the things they said and did to try to avoid resolving those early problems. The credibility of this industry is still strained by their early claims that BPL would be inaudible to licensed radio users or that BPL on overhead power lines is a point source and other technical nonsense.
But even my experience in Houston shows me that if BPL is to avoid interference, it can do so on only the spectrum it protects with notches. In Houston, that includes the Amateur bands. It does not include shortwave bands or CB. The fact that, even with the care CenterPoint has taken to do things right, I found two nodes operating above the FCC limits tells us that considerable care must be taken to do things right. IMHO, only those companies that are willing to listen to and respond to those with interference complaints and those willing to carefully check each node installed have a shot at making it work. And right now, those conditions don't exist with every BPL manufacturer, integrator or electric utility.
One thing I do know, however -- gratuitous insults are not going to solve anything. Many of BPL200mbs's posts have been deleted for the insulting terms he is fond of using. Even "Mr. Hamster" was intented to evoke anger, not understanding.
»www.arrl.org/bpl
Ed Hare
ARRL Laboratory Manager
225 Main St
Newington, CT 06111
Tel: 860-594-0318
Email: w1rfi@arrl.org | |
BPL 200 Mbps
join:2006-11-05
Toms River, NJ
| it should be up to 600Mbps BPL ... !!!
up to 600 Mbps !!!
Corinex Communications showcases the 600Mbps
Multi Dwelling Unit Gateway at HITEC 2006
World’s First MDU Networking device that offers up to three simultaneous
200Mbps Powerline and Coax backbones within a building
(»broadbandoverpowerlines.blogspot···ces.html)
re: "In addition to utilizing Ambient’s industry-leading, FCC-certified X2 BPL Access Node (with up to three 200Mbit BPL interfaces), Ambient-designed next-generation overhead and underground couplers and BPL modems in the deployment, Ambient will provide the engineering and technical support needed to design, support and assist in the deployment and management of the network. The deployment will also include X2 nodes with integrated 802.11a/b/g Wi-Fi support to provide wireless access. "
(»http://broadbandoverpowerlines.b···has.html)
Will this answer your BANDWIDTH slowdown fear ?
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Unleash the opportunities of a SYMMETRICAL 200Mbps “Smart Grid”, IPTV and in-home networking for business optimisation of your commercial opportunities of BPL/PLC with killer applications & services: in-home MDU networking, IPTV and triple-play... !!! | |
W1RFI
join:2003-05-12
Burlington, CT
| Nice Ambient commercial.
said by BPL 200 Mbps :it should be up to 600Mbps BPL ... !!! ... Will this answer your BANDWIDTH slowdown fear ? I'm not sure what fear you think I have, but so far, the systems I have seen don't come anywhere NEAR 200 Mb/s to the end user.
And my quip about your screen name is that 200mbs is 200 millibits/second. You may want to use the correct capitalization and use a capital M to indicate megabits/second.
Ed | |
drjim
Premium,MVM
join:2000-06-13
Torrance, CA
clubs: | Thanks again, Ed, for providing some facts based on real world use and testing.
73, Jim KQ6EA
--
One man's Magic is another man's Engineering. | |
rf_engineer
join:2003-08-04
USA
| reply to BPL 200 Mbps
said by BPL 200 Mbps :it should be up to 600Mbps BPL ... !!! up to 600 Mbps !!! Will this answer your BANDWIDTH slowdown fear ? No. I haven't seen a BPL subscriber getting anything near 200 Mbs. (If there was a subscriber getting 200Mbs, you would certainly see press releases and articles here.) And if you knew anything about networks, 200 Mbs would be the backbone speed, not the end user speed. Has any vendor gotten 200 Mbs BPL to work on an overhead line and actually deliver a full 200 Mbs? | |
W1RFI
join:2003-05-12
Burlington, CT
| Shannon's information theorum says that with absolutely perfect modulation, to attain 200 Mb/s using a 20 MHz channel, the signal-to-noise ratio at the end of the circuit would have to be 30 dB. With an estimated 15 dB loss between an injector and the repeater located 1000 feet away, the system would have to start out at 45 dB signal-to-noise. Unfortunately, at typical noise levels, that would put the system well above the FCC emissions limits.
At a more reasonable 10 dB signal-to-noise ratio, 70 Mb/s is the upper theoretical limit.
This assumes perfect modulation and demodulation. In practice, getting within 10 dB of the Shannon limit is considered to be pretty good. That would give a typical 20 Mb/s to the end user, not counting any bits used for system overhead.
The only G2 system whose data rate I tested had other indications that something was actually wrong with the system, so its results are really not useful at this time. I do expect to get back there, though, and as these other commerical systems come on line, sooner rather than later, we will see independent speed tests done for G2 as they have beend done for G1.
Ed | |
rf_engineer
join:2003-08-04
USA
| said by W1RFI :Shannon's information theorum says that with absolutely perfect modulation, to attain 200 Mb/s using a 20 MHz channel, the signal-to-noise ratio at the end of the circuit would have to be 30 dB. With an estimated 15 dB loss between an injector and the repeater located 1000 feet away, the system would have to start out at 45 dB signal-to-noise. Unfortunately, at typical noise levels, that would put the system well above the FCC emissions limits. At first I was thinking your 20 Mhz channel was a bit too small, considering there's about 80 Mhz of spectrum BPL is using (1 to 80 Mhz). But the lower 21 Mhz is not contiguous space as there's the mandatory NTIA notches and the amateur band notches. Then there's frequency reuse that needs to be considered. Each BPL repeater segment needs a different frequency band as the repeater can't prevent RF from one segment bleeding onto another; you're depending strictly on line attenuation for isolation between segments. I'm guessing n=3 or n=4 frequency reuse? Last you need separate frequencies for transmit and receive, so you need double the frequency bands/"channels". So, it's conceivable that one would need six to eight "channels" to work with. So your 20 Mhz channel figure is reasonable as the required number of channels would fit into what's usable in the 80 Mhz of spectrum.
Your 15 dB of loss between the coupler and repeater seems low to me, especially if you consider VHF frequencies. Have you seen this in practice or in your modeling?
At a more reasonable 10 dB signal-to-noise ratio, 70 Mb/s is the upper theoretical limit.
This assumes perfect modulation and demodulation. In practice, getting within 10 dB of the Shannon limit is considered to be pretty good. That would give a typical 20 Mb/s to the end user, not counting any bits used for system overhead. And no ISP in their right mind would give an end user the same speed that they have on their backbone. It would be too easy for one user to saturate the network and wreck the service for others. 10 to 25% would be reasonable. | |
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