Slashdot Mirror
FCC on Ultra-Wideband, DSL Services
ibirman writes: "According to Yahoo, the FCC has approved limited use of Ultrawideband (UWB) technology above 3.1 gigahertz. The article states that Sprint PCS among others has been campaigning to keep the minimum above 6 gigahertz claiming "interference". From what I have read, interference is not an issue, so I wonder what their real agenda is? Funny that the article does not mention that UWB could revolutinize high speed wireless networking." There's a Newsbytes story that decribes an upcoming ruling on DSL providers, which would exempt DSL carriers from the open-access requirements in place for most telephone services. There are a few links to statements on the front page of fcc.gov, but I don't see the actual orders for either of these yet.
sPh
It's possible that a UWB system could interfere with these, but your UWB transmitter would have to be very close to your cell phone or TV. It's only been approved for very short distances, so there shouldn't be much risk of interfering with other people's cell phone reception, just that in your own home or office. Still, it's an interesting loophole for people who want to block cell phone signals. ("No officer, this isn't an illegal cell phone jammer, it's a UWB network!")
Larry Fullerton, now of Time Domain, invented a radar and wireless system based on pulses of energy less than a billionth of a second in duration. The scheme is known as ultrawideband. Although ultrawideband pulsed radar has been around for decades, the U.S. Patent and Trademark Office decided in 1987 that Fullerton's system was original enough to be patented.
In the early 1990s, however, Thomas E. McEwan, then an employee at the Livermore lab, came up with a related idea for a "micropower impulse radar" that employed different circuitry and worked at much lower power. His device can function for years on a couple of penlight batteries, he states. He got patents, too, and assigned them to his employer, which started licensing the invention to manufacturers. But McEwan failed to cite Fullerton's invention as "prior art" in his original patent application.
Sprint backed the wrong horse and spent millions in licensing fees to Livermore lab. Their opposition to UWB is pure vindictiveness.
Now Time Domain refuses to license UWB to sprint, putting them at an extreme disadvantage to ATT and other competitors.
Beautiful technology though... this is one of those real "could change the world" technologies like the step from Analog to Digital signaling
If voting were effective, it would be illegal by now.
According to my frequency allocation chart, the 4.2 to 6GHz band is reserved (dually with some other things) for 'Experimental PCS'. Perhaps they're worried about people running amok in 'their' band?
Thanks,
--
Matt
As you can imagine, this introduces some inefficiencies in routing! The airlines would desperately like to go to "Free Flight", which would allow them to route airplanes as more or less as desired (this is a vast simplification for you aero-nauts out there, and leaves out the problem of hubs entirely).
But Free Flight depends not only on GPS, but the advanced location services that the FAA and other GPS consumers would like to roll out over the next ten years. Those services will require absolutely pure signals on the existing allocated freqs, and possibly more freqs as well.
So they don't want anything messing with the GPS signal.
sPh
had a story about this on Morning Edition this morning.
a m
Here's the audio file of the segment:
http://www.npr.org/ramfiles/me/20020214.me.07.r
A commentator on there seemed to think it would interfere with all sorts of things acting like a "layer of jelly" which the poor little GPS device could not operate through.
Most people would die sooner than think; in fact, they do.
First, comparing the two systems' measurement accuracy is apples and oranges. UWB might be usable as a point-to-point ranging source, sort of like a stud finder, but it only tells you how far a given object is from, say, your handheld transmitter. GPS, on the other hand, gives you a three-dimensional position fix anywhere on earth (as long as you can see a reasonable patch of the sky). The two are simply not measuring the same thing. (Furthermore, a properly set up variant of GPS called a "differential" setup can deliver accuracy of better that 1cm.)
Second, UWB is not necessarily as low-power a system as is claimed in the article. Typical UWB transmitter power levels are around 1 milliwatt (typical cell phones are around 1 watt), which is ten times higher than what Cringely claims. (The idea is that because the energy is spread across a wide swath of frequencies, the power in any one band is relatively low.) Furthermore, UWB power levels are strongly dependent on the desired distance between transmitter and receiver.
Third, applications are currently being developed for using GPS and its variants indoors.
Finally, UWB can pose problems for GPS. The nominal GPS signal is, by design, about 15dB below the ambient noise floor -- that is, it's about 30 times quieter than the static you'd receive if you tuned a radio between stations. Thus GPS can be particularly sensitive to even very low-level intereference. I work in a GPS Lab and we have been examining the potential UWB-GPS interference issues for about the past two years. The point is, this is a big deal because GPS will likely be used in a number of safety-critical applications (e.g. landing airplanes) within the next 5-10 years. Dismissing the potential objections to UWB out of hand is therefore not only ill-advised, but potentially dangerous.
The list of publications on the lab's main page includes papers with detailed explanations of the points I've made above.
-FP
It's from radio terminology from (human) generations ago.
ELF (extremely low frequency)
VLF (very low frequency)
LF (low frequency)
HF (high frequency)
VHF (very high frequency)
UHF (ultra high frequency)
microwave (microwave - subdivided in to bands designated by one or two letters which HAVE changed)
IR (infrared)
X-ray (x-ray)
Gamma ray (gamma ray)
I think there may have been a medium frequency but I'm not sure. There's also:
IF (intermediate frequency) which is unrelated, referring to an internal signal in a superheterodyne receiver.
RF (radio frequency) which is more generic, covering everything from ELF to UHF or perhaps microwave, although its use tends to drop off outside the range between LF and HF.
Similarly there was narrow band and wide/broad band (referring to signal bandwidth significantly less than, or more than, that of AM or early-version FM signals modulated by telephone-quality voice). It's logical for radio engineers to apply the same set of modifiers when they start working with more extreme schemes and have to differentiate them from previous technology.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
NASA's Aviation Safety Reporting System (ASRS) database has a large number of reported incidents where cellular telephones, and other electronic devices, have caused interference with aircraft communications and navigation equipment.
Mea navis aericumbens anguillis abundat
In last week's EETimes, there was a good intro to UWB and its challenges, as well as a discussion about the (considerable) importance of the FCC ruling that just took place (in a front page story). The Web versions are:
--
Mad science! Robots! Underwear! Cute girls! Full comic online! http://www.girlgeniusonline.com/
You'd be limited with UWB in "bandwidth" which should read transmission capacity only by the speed with which you couple pulse a radio signal. If I can get 100 pulses of a 30m signal that is a hundred bits per second I can send you. The more pulses I can transmit the more data I can transmit. At least this is the best understanding of UWB I have. Old habits die hard for a lot of people. Here is a good EE Times story about UWB.
I'm a loner Dottie, a Rebel.