Posted on 01/17/2005 11:06:27 AM PST by anotherview
10:31 14 January 2005
Exclusive from New Scientist Print Edition
Barry Fox
After the tsunami hit Sri Lanka on 26 December, Victor Goonetilleke, head of the island's amateur radio society, delivered a short-wave radio set and two 12-volt car batteries to the prime minister's emergency headquarters in Colombo. At the same time, three of his friends drove through the devastation to Hambantota, on the hard-hit south-east coast, where they set up another battery-powered short-wave radio.
For two days, while the military struggled to restore electricity supplies and phone lines, the prime minister was able to use the short-wave link to talk to staff on the ground.
Short-wave signals from Sri Lanka, the Andaman Islands and mainland India also helped to spread news of the disaster around the world. The same happened after the 9/11 attacks and last year's hurricanes in the Caribbean. When phones and mains electricity are down, making the internet unusable, short-wave radio enthusiasts are able to maintain emergency communications.
But not, perhaps, for much longer. Plans to deliver broadband internet signals to homes and businesses down mains electricity cables, rather than telephone lines, could cause interference that will drown out the faint signals from distant short-wave transmitters. Unshielded cables
Power companies in the US and Europe are pressing ahead with the technology, with the aim of setting up in competition to existing phone-based services. The downside is that the packets of internet data pulsing down unshielded mains cables makes the cables behave like aerials that send short-wave interference beaming out over a wide area.
Unless interference of this kind is tightly controlled, it could spell the end for emergency short-wave communications. "A few extra decibels of interference from future networks and I would not have been able to hear the news from amateurs in Sri Lanka, India and the Andaman Islands," says Hilary Claytonsmith of the International Amateur Radio Union's UKbranch.
The threat began when the US government gave the go-ahead to broadband over power line (BPL) technology in October. And the European Commission (EC) is close to approving its own version, called power-line communications (PLC). The names are different but the technology is the same: broadband data is sent into people's homes as a high-frequency signal piggybacked on the 50 or 60-hertz mains supply. Unhappy coincidence
Because the mains is a noisy environment with ever-changing patterns of interference from sockets, switches, control circuits and electric motors in appliances, the power-line data must be spread over many high-frequency carrier signals if it is to be delivered at the 5 to 10 megabits per second that these services are aiming for.
The carrier frequencies used range up to 30 megahertz - which by unhappy coincidence is the radio band that travels best around the world. It is used for amateur radio, short-wave broadcasting (such as the BBC World Service and Deutsche Welle) and includes several dedicated emergency frequencies (see graphic). Because these frequencies bounce off the ionosphere, they carry long distances, which makes them ideal for long-range intercontinental broadcasting.
When the US Federal Communications Commission (FCC) gave the go-ahead to BPL, it ruled that at frequencies up to 80 megahertz service providers must use filters on their household equipment. These could be set by a service engineer to chop out any internet transmission frequencies shown to be causing interference to any short-wave radio receivers nearby. The EC and the European Committee for Electrotechnical Standardisation (CENELEC) are trying to set similar filtering rules. Deciding on importance
But radio amateurs fear that the rules will allow the filtering to be lifted if it is having a serious effect on internet access speeds. The EC says it wants firm rules that balance "technical, social and economic" factors against the "importance" of services which suffer interference. But who is to decide what is more important, and on what grounds, the radio amateurs ask.
Michael Copps, the one FCC commissioner who opposed BPL, believes the organisation has made a rod for its own back. It is going to have to "work hard to monitor, investigate and take quick action" over any power-line internet interference to radio amateurs and others, he says.
Some technical fixes may be in the works though. The BBC, for instance, is developing a PLC modem that makes use of the fact that the short-wave frequencies for broadcast radio change throughout the day, as ionospheric conditions dictate. The BBC modem detects which frequency bands are in use at any one time - and filters them out. Such technology is not part of any PLC or BPL system currently in trials, however.
BPL ping
bpl
Infrastructure.
I live next to power lines and I can't get shortwave stations at all. All buzzing noise. I can barely pick up the strongest AM stations.
If this goes through, it'll really suck.
I have cable internet at college so its not really a problem. Right now I'm VNCing into my home computer to do my downloading.
I do know that broadband will eventually be coming to the rural areas. There are already government grants for nonprofits who wish to setup wireless internet in rural areas. I doubt BPL will be as cost effective as WiMax. IIRC, WiMax has about a range of 30 miles and about 70Mbps bandwidth.
Bottom line = money for the President's friends and contributors in the energy industry and utilities. I have no problem with that if the technology made sense. In this case it does not and the FCC pushed new rules through. NTIA issued a negative report on BPL, word came down from the White House, and it suddenly was possible that the problems could be fixed in their revised report.
This is within my area of expertise. The problems cannot be fixed.
Now, there is a competing system that operates above 800MHz that is very promising indeed.
Go to the head of the class. WiMax is far more cost effective and can handle much higher bandwidths.
WIMAX technology IS promising. WIMAX base stations and repeaters could piggyback on select existing cellular towers for maximum coverage.
"Why is the government pursuing BPL? We have excess capacity of fiber backbones."
Because the scent of money is in the air.
You hit it on the head... and it wasn't just NTIA. ARINC (consortium responsible for HF communication with aircraft) sent a comment letter to the FCC that was practically smoldering.
This is a clear cut case of stated homeland security goals being compromised for the interests of campaign contributers. On the one hand the DHS has told the hams that they are essential to national emergency communications needs - while at the same time BPL is being pushed through which threatens to jam essential (see below) HF frequencies. 
Even though BPL is being sold as an answer to rural broadband there is no evidence that the power companies would find it economical to roll it out in those areas.
The power companies are just looking for an additional, unregulated, income stream.
Correct...there are miles of black/dark fiber, laying in wait un-implemented.
MD
BINGO!
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