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Broadband Over Gas Lines — a Pipe Dream?
prostoalex writes, "USA Today says we might see some progress in broadband over gas pipes, as startup Nethercomm (warning: Flash site) is working on the technology to deliver broadband Internet over this medium using ultrawideband radio. According to the article: 'Broadband in Gas would require installation of an ultrawideband transmitter that's linked to an Internet backbone... at a gas company's network hub. A receiver would be placed at a customer's gas meter. Build-out costs are about $200 per household, Nethercomm says. By contrast, broadband over power lines costs about $600 per household, while phone and cable TV networks each cost well over $1,000 per home to build.'" The article ends on a downbeat note. The upcoming trials that Nethercomm touts are difficult to confirm: "We're intrigued by the technology, but we never got that far in our discussions," says a gas company spokeswoman. And the ultrawideband chip company that had been working with Nethercomm, Freescale Semiconductor, has turned its attention to other projects.
All the newer gas pipes around me come out of the ground as a flexible plastic rather than a metal pipe line. And I live in New Orleans, where we're getting a lot of new gas lines! Is this supposed to be carried by the metal in the pipes or is there going to be some kind of translator in the streets that takes care of it? This is, of course a moot point, since we're supposed to get muni wi-fi, but don't other cities have plastic pipes too?
Suck a lemon?
Now, I may not know enough about this technology, but my understanding of UWB (Ultra Wide Band) is that it does not reach very far, and is better suited for WPAN's... Heres is the definition straight form googles mouth.
Ultra-wideband (also UWB, and ultra-wide-band, ultra-wide band, etc.) usually refers to a radio communications technique based on transmitting very-short-duration pulses, often of duration of only nanoseconds or less, whereby the occupied bandwidth goes to very large values. Ultra-wide-band may also be used to refer to anything with a very large bandwidth (e.g.: a type of sampling rate in the Speex speech codec). This article discusses the meaning in radio communications. en.wikipedia.org/wiki/Ultrawideband
anyone care to explain this better to me?
Look up waveguides. Metal-walled conduits can be used to transmit RF energy. This doesn't necessarily mean you can just slap a transmitter onto a gas line.
Sending suitably high frequency EMR through a metal pipe is called a 'waveguide', and its pretty much the standard way to deal with microwave communication. In waveguide the sides do indeed absorb some energy, but with smooth sides and good conductors, the losses are quite small. You need to avoid certain gases, which interact with the microwaves, absorbing the signal. Water is probably the most notable, but with suitable choice of frequencies you can step around most gases (which is why we can send stuff through the air).
All the gas pipes in my city are made of plastic, making this whole idea quite improbable.
No, it's an opium reference. Crackheads don't sleep.
the signal is sent inside the gas line...the type of material doesn't matter. Think radio waves through the dense vapor in the gas lines (hence the ultrawideband)
A transmitter is installed at the gas companies end...and a receiver is installed at the customer end (and obviously a transmitter of some sort as well).
They don't specify in the article directly, but they imply that they're not using the pipes as conductors in the traditional sense, but rather transmitting the signal within the pipes, using them as waveguides. Waveguides are an excellent transmission medium for very specific frequencies -- namely the resonant frequency and its harmonics -- but they're very expensive, and dents, dings, and improper couplings add VSWR, which could (and often does) attenuate the signal dramatically or even entirely. Bends in waveguide also cannot be more than 1/2 the wavelength, so right angles tend not to work well. The solution they've proposed is to use ultrawideband, which apparently just means using a large swath of spectrum rather than a single frequency, so that if the VSWR of one frequency is too high, another frequency should still get through.
Anyway, having wires running along the pipe would make no difference, since the signal is internally reflected, not transmitted through the metal. Essentially you have two small antennae -- one at each end (although obviously more than that for this proposed setup) -- and the antennae is traditionally 1/4 wavelength, placed at a specific location within the waveguide to prevent phase cancelling. Since the signal is internally reflected (like fiberoptic, for example), nothing on the ouside of the "pipe" matters. You could possibly install coupling from the point where the copper pipe ends to some external line, but I think the existance of the plastic pipe would screw things up nonetheless, and the tracer wire likely isn't shielded or twisted, meaning it's a shitty transmission medium.
I've never heard of waveguide made out of plastic, but the wikipedia article says it's doable for optical frequencies. Obviously fiberoptics are fiberglass, but I sort of doubt it would work well for RF. If I'm not mistaken, it's the optically reflective characteristic of glass which makes fiber work, not the fact that it's a dialectric. I think that plastic would just get hot and melt/burn -- not a good thing for a flammable gas line.
At any rate, I doubt the system would work at all, since the network of pipes is so complex. Some houses may get great reception at all frequencies (doubtful), while others might get no signal at any frequency (almost guaranteed). Also, any time someone adds to or modifies the network of pipes, they'll change the transmission characteristics of the entire system. It's difficult enough to keep an RF waveguide system operational when it's purpose-designed, let alone when it was never a design consideration. The proposed ultrawideband solution may help, but I doubt it would work well.
https://www.eff.org/https-everywhere