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Spark Gaps and Ultra Wide Band Data Transmission
Embedded Geek writes: "It sounds like the revenge of Marconi, but Scientific American has a story about the use of spark gap technology for Ultra Wide Band (UWB) data transmission to send data at 100 to 500 Mbps across short distances (five to ten meters). As with every new technology, 'engineers expect these UWB units to be cheaper, smaller and less power-hungry than today's narrowband radio devices,' but there might be some truth to the hype. The secret appears to be the lack of a carrier wave, allowing use of wide swaths of the spectrum for transmission (the few comments I read at the FCC site referenced in the article addressed spectrum allocation)." Read below for a few more links, too.
"The article pitches the technology as a challenger or succesor to Bluetooth and 802.11a. There are several commercial companies investigating the technology (Aetherwire, Multispectral, and others are cited in the article) and Intel has a paper cited in the article. Spin off applications from the components needed to make this technology work might include a GPS style system accurate to one meter and a radar technology that would allow seeing through walls for construction, rescue, and (ahem) law enforcement."
Cringely already had a good article about this. It can be found here.
No, I don't think the problem is a health one, but as has been pointed out, I think it will up the background noise level, meaning that other users of the rf spectrum will have less chance of using weak signals as they will be lost amid the higher noise levels. Ask any amateur radio enthusiast about computer/cordless phone noise etc, and other man made interference.
Radio HAMS are to radio like we are to computers, they see the problems before most people have heard of the cause. Marconi spark transmitters can have a vast range, due to HF emmisions ( a Marconi spark transmitter made the first America-England transmission), OK these things are going to have a bandwidth limitation, but people use 3ghz ++ too, If these devices become common, then services on these microwave bands will suffer to some extent.
Best mitigating circumstance is that amateur/professional microwave stuff is going to be using highly directional antennas, which will help keep signal/noise ratio high. There will I think be a detrimental effect though overall.
Merlin --- We're an autonomous collective... Help, Help, I'm being oppressed!!
Yes, and about 5 thousand watts were being broadcasted in almost every direction just to do 3 watts of lighting. It's emmensely inefficient. Fun, and interesting. But impractical beyond belief.
Contrary to popular belief, coding is not all free blow-jobs and beer. Those things cost MONEY!
S/N is the signal-to-noise ratio, W is the bandwidth, C is the (theoretical maximum) data capacity.
It's easier to get capacity by raising the bandwidth consumption than by raising the power level, since the S/N is inside the logarithm. Then a virtuous circle gets started, because you can drop power level, which means someone nearby can operate without having you interfere with them, which means more people can each have whatever data rate C turns out to be.
This is really just a radical extension of spread spectrum radio.
Two companies that have been pioneers in UWB are Pulson and Aetherwire.
Pulson (and its predecessor company, Time Domain) has been desparately trying to commercialize this technology for radio communication for years. More than five years ago they demonstrated a few-milliwatt UWB radio with 100-mile range. They have mostly been held back by patents taken out by Lawrence Livermore. Livermore claims to have invented all of this stuff, and has been rediculously rough on licensing. Also, the FCC has been unclear until very recently on how it would license UWB.
Aetherwire has attempting to use UWB technology to build localizers, basically extremely short range, extremely low-power peer-to-peer short-range version of GPS. The localizers would all cooperate at keeping track of where the other ones were within a few hundred meter radius. If you've read A Deepness in the Sky by Vernor Vinge, it's all about localizers.
Now that the FCC has cleared the way, I expect to see tremendous progress in UWB. It's going to revolutionize many fields, from radio to positioning to radar.
thad
I love Mondays. On a Monday, anything is possible.
Did anybody else think this was an illogical spot in the article?
Ironically, the more challenging technical problem appears to be finding ways to stop other emitters from interfering with UWB devices. This area is one in which narrowband systems have a decided advantage--all such systems are fitted with a front-end filter that prevents transmitters operating outside their reception bands from causing trouble. Unfortunately, a UWB receiver needs to have a "wide-open" front-end filter that lets through a broad spectrum of frequencies, including signals from potential interferers. The ability of a UWB receiver to overcome this impediment, sometimes called jamming resistance, is a key attribute of good receiver design. One approach to improving jamming resistance is to install so-called notch filters that attenuate those narrow parts of the spectrum where interference is known to be likely. Another protective measure that has been developed would be to use automatic notch filters that seek out and diminish the signals of particularly strong narrowband interferers.
First: part of the point of a plain UWB system is that you ignore interference by looking for your signal in ALL of the freqencies you use, at the same time. If a pulse shows up across enough of the range, it's probably good, and if it's actually a blast from another UWB source (a light switch, perhaps?), that's what error correction's for.
Second: there's the issue of ignoring interference. I suppose that at these ultra-low ERPs, they could be exempt, but as they're using bandwidth allocated to other services, they've got to meet Part 15, part of which specifies that they must A)not cause interference to licensed services, and B)accept interference from licensed services.
Like I said, they meet the first one pretty well, but part of the second one is to force awareness on the user of the Part 15 device that they're conflicting.