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."

Comments

Because of the short pulses

[BiggestPOS]

These are supposed to look like noise to anything else transmitting. Since they spread the signal around a LOT of specturm, they are generally just raising the level of background noise.... What happens when enough of these devices get out there, and the noise floor rises to equal Everest?

Re:Because of the short pulses

[n9hmg]

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.

Intel looking to fabricate UWB radios on CMOS

[JohnDenver]

Think about it: Short-wave radios fabricated on a chip that are capable of 100-500 Mbits/sec.

1. Your PDA would be your CPU + Memory
2. You could put your harddrive in your coat pocket.
3. When you walk towards a monitor, you could wirelessly dock to it or the neighboring keyboards/mice.

This is actually an old article, but I honestly believe if Intel gets this right, UWB is going to be HUGE.

Here's another article:
http://zdnet.com.com/2100-1105-840393.ht ml

IANA Explosives Expert but...

[Anonymous Coward]

"...For example, rather than picking up recorded movies at the video store, we may end up downloading films using a portable mass-storage unit and UWB wireless transmission while filling the car up at the fuel pump..." The whole spark gap transmiter + gasoline fumes seems bad for some reason.

Think of it as Bluetooth on Crack

[JohnDenver]

100-500 Mbits/sec can pretty much serve as a wireless bus for most of your components. With that kind of speed, you could physically seperate your (CPU+Memory) (Harddrive) (Monitor)

Not to mention all of the wireless possibilities linking to Home Entertainment system, Car, Access Control Devices, Etc.

Given Intel's goals to make UWB cheap as they're trying to fabricate it on CMOS it would be everywhere where wires used to be.

MY ERROR 1/3000 of a cell phone Hair Dryer

[JohnDenver]

1/3000 of a cell phone.

Ultrawideband communications systems would share the same problem except that they deliberately operate at power levels so low that they emit less average radio energy than hair dryers, electric drills, laptop computers and other common appliances that radiate electromagnetic energy as a by-product. This low-power output means that UWB's range is sharply restricted--to distances of 100 meters or less and usually as little as 10 meters. For well-chosen modulation schemes, interference from UWB transmitters is generally benign because the energy levels of the pulses are simply too low to cause problems.

A typical 200-microwatt UWB transmitter, for example, radiates only one three-thousandth of the average energy emitted by a conventional 600-milliwatt cell phone.

Pulson and Aetherwire are great companies in field

[Thagg]

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

No a magic technology.

[3flp]

This is just a different method of sharing spectrum among different users. The currently used methods are pretty good. They have been under development for about 100 years. The Rf spectrum is a limited resource. The amount of information that can be transmitted over the spectrum is limited by Shannon's theorem (read his 1949 paper). This limit can't be increased. What UWB does is spreading its information over really wide bandwidth, raising the noise floor for everybody else. If there are enough UWB transmitters around, they will interfere with each other to the point of uselessness. Also, this will f**k up every other user of the Rf spectrum. In addition, with UWB, the spectrum can't be managed by assigning different frequency bands to different entities. Everyone jsut uses all of the spectrum all the time. The strongest transmitter wins. Sounds like this technology has a good chance of being approved in the US...