Slashback: Privacy, Spectrum, Location

Slashback tonight brings you yet another handful of updates and amplifications to previously posted stories, including some naysaying to Lessig's idea of the spectrum as commons, more free books from Baen, and the European answer to GPS. Read on for the details.

Sir, you just need to trust us. geekee writes "An article on CNN claims that the proposed passenger-screening system for air travelers is much more innocuous than previously claimed. Now it is claimed that the Transportation Security Administration "will not view credit records, traffic violations or other personal data", according to Admiral James Loy. He also claims records of travel will not be maintained. "Airline reservation agents would provide a traveler's name, address, phone number, date of birth, and travel plans to the TSA, which would then check that information against a variety of commercial databases and an FBI watch list.", according to TSA spokeperson Heather Rosenker."

Thinking of the children means more than hiding their eyes. Jim Tyre writes: "You pointed out that my censorware.net piece ["CIPA Before the Supreme Court"] provided a nifty link to where the official supreme court oral argument transcript would be when available online. It's now available."

What's good for the mercantilists ... wait, no doesn't have the same ring. Lawrence Lessig says that the current radio spectrum is vastly underutilized, and that new technology can extract much more use from it, creating a true radio commons. Zo writes to point out that many Salon readers disagree: "Radio waves, bandwidth, the spectrum. . .Don't we know *anything* for sure?

Sir, these books smell fine ... what's the catch? silentbozo writes "Avid Slashdotters will remember the Baen Free Library, which puts up free web versions of Baen titles for ANYONE to download and read without having to mess around with encryption and DRM. They went a step further with this experiment last fall with the release of David Weber's War of Honor which had a bunch of novels in html, rtf, doc, palmdoc, and othe formats on CD (bound into the hardcover), which you could copy and give away to anyone. Well, they're at it again. In May, they'll have another CD for those of you who didn't get War of Honor, bound into John Ringo's Hell's Faire.

I got hooked reading John Ringo's books after browsing through my copy of the War of Honor CD... and it's a great way of catching up on the previous books in the series. Hell's Faire looks really good - I personally am looking forward to finding out what happens to the O'Neals as they fight the Posleen on Earth, and to the crew of Bun-Bun... Eat anti-matter Posleen-boy!"

As secure as ... well, you pick. Anthanos writes "pGina [http://pgina.xpasystems.com], a modular authentication framework for Windows, has come a long way since it was last noted on /. nearly a year ago. Since then a full-fledged LDAP plugin, PAM plugin, and chaining have all become part of the feature set. The kicker is the recently released Slashdot plugin, which allows authentication of Windows clients with... yup you guessed it, Slashdot Accounts! XPA Systems has even begun offering services revolving around this GPL product. Seems this may be the solution for people looking to merge authentication of Windows clients with MacOSX, Solaris, and other *nix boxen."

Let's see a handheld that uses both, please ... Mattias Östergren writes "Well aware of the risks with dependency of GPS the European Space Agency (ESA) have developed their own satellite navigation system, EGNOS. EGNOS is more accurate than GPS and the signal also tell you how much it could be off.

The first reference station have just been installed on the roof of the Land Survey in Gävle, Sweden. There is a Swedish press release about it."

Comments

Subscriber Preview

[Oculus Habent]

You know, previewing a story before it makes the page is really worthless on Slashback when you can't "Read More"

Re:Subscriber Preview

[iCEBaLM]

Only a fool would like MS-Vanilla over GNU/Butterscotch when there are so many reasons to eat butterscotch! It has enhanced flavor functionality as well as color functionality which distance itself so far from vanilla it's not funny. It's like comparing apples to oranges!

-- iCEBaLM

Looks like it's only usable in Europe for now ...

[dougmc]

About EGNOS ...

Consisting of three geostationary satellites and a network of ground stations,

If there's only three satellites, this must only be usable in Europe for now. Too bad -- 5cm accuracy would be sweet!

(Actually, the existing setup is sweet, but 5cm would be much sweeter.)

Re:The editors are morons!

[parsnip_soup]

Well the section is called slashBACK, meaning followups and information related to previous articles.

TSA background checks?

[teamhasnoi]

What does my credit have to do with whether or not I should be in an airplane? Does shitty credit mean you're more likely to take a plane down with you?

If so, how can anyone from Arkansas go anywhere?

But seriously, all this background check BS is too much. Scan people and baggage. Lock the cockpit. Put an 'air cop' on board. What can you do? Not pay for movie headphones? (Credit be damnned, they make you pay in cash.)

Background checks are unnessasary if the airport is secure in the first place.

Ahh...I see. Its cheaper to run my SS/DL #s and invade my privacy than it is to change a door on an airplane. It must be, or airline would have done it a long time ago, because they care about people!^W airplanes.

Re:TSA background checks?

[mmol_6453]

It has to do with statistics. Theoretically, the more information you have per data point, and the more datapoints you have, the more accurate your results are.

The problem is, if you have too much information per datapoint, you start getting false positives.

Think of it like your Bayesian spam filter(God, I LOVE Moz 1.3!)...the longer you train it (the more spam messages you feed it), the better it will be at recognizing the types of messages you give it.

However, if you, say, start feeding it messages from your ex-spouse, it will start homing in on on other stuff. Possibly personal mail, or maybe legal notifications (depending on your situation. :) ).

Re:TSA background checks?

[Anonymous Coward]

1) They said they were NOT doing credit checks.

2) OBVIOUSLY this is more than just deciding if a single individual is "secure" for a single flight. They are attempting to track individuals that are on "lists". If a suspected terrorist gets on a plane, the FBI now has till that plane lands to decide if they want to pay him(her) a visit or not. If 20 of them all get on planes in one day to one location, well then...

Re:TSA background checks?

[sixdotoh]

Put an 'air cop' on board

just as a side note, the term is actually 'air marshall.' which are some pretty highly trained, butt kickin, federal agents.

Re:TSA background checks?

[Anonymous Coward]

Any checks are too much. If they want to place a policeman on board ok, maybe two that do not know each other just encase.

The government believes it can get around the Constitution, because air travel is "voluntary". That means they can do the same to trains, ships, busses, and even buying a car.

The worst part is they believe this will work!

First why would some one walk into an airport to take out plane? When O'Hare and Orlando, to name two, have runways ends that are attached to 6 lane freeways. Searching your car pulling in to the airport is a joke. Search every car driving pass the end of a runway, with a plane only 50 to 100 ft over their head. Being that close, a piece of wire and a hook, that plane is yours!

It is time for people to stop believing it will get better... At best, McCarthyism is back to stay, and at worst Germany won W.W.II.

Re:TSA background checks?

[jackb_guppy]

And how do you know that "air marshall" is still a marshall on this flight?

You need two, that do not know each other. You allow all passengers to carry guns, so you do not have the good guys be known by bypassing security.

So we will have to remove all security.

So, let UAL and American go out of business, serves our goverment right.

Re:TSA background checks?

[mmol_6453]

Right...so they shoot each other?

Air marshalls get onboard incognito. The only sign that you're looking at one is that he got to bypass the metal detectors by flashing his wallet at the security gaurd.

Re:TSA background checks?

[mmol_6453]

idiot me...I only read half the post.

Anyway, people are too paranoid about guns to be comfortable with anyone having a gun onboard, let alone normal passengers.

Unfortunately, not many people carry...Only four people I know, and I live in a highly conservative area.

Re:TSA background checks?

[Aaron M. Renn]

Your credit actually seems to have a lot to do with a lot of things. Poor credit is correllated with a lot of things. For example, those with poor credit are more likely to have auto accidents and file claims. In fact, one insurance company I know had studies indicating that credit history was the most important predictor of future auto claims - even moreso that prior auto claims. Amazing.

This makes a certain amount of sense. While many people do end up in credit trouble through no fault of their own (catastrophic medical bills, job loss, etc), very often people who end up with poor credit do so because they are unable to properly manage their fiances. Perhaps this indicates they are also irresponsible in other areas of their life.

Re:TSA background checks?

[homer_ca]

I think the theory goes that if someone has NO credit history (as opposed to a good or bad credit history), it's almost the same as having no past, and there's a higher chance that this person is using a false identity or an alias. Not that it would have helped with 9/11 because the hijackers travelled under their own names.

Re:TSA background checks?

[Moses Lawn]

Anyway, people are too paranoid about guns to be comfortable with anyone having a gun onboard, let alone normal passengers.


The main reason people don't want guns on board planes is because having bullets flying around a pressurized cabin is a Known Bad Idea.

Re:TSA background checks?

[Moses Lawn]

This makes a certain amount of sense. While many people do end up in credit trouble through no fault of their own (catastrophic medical bills, job loss, etc), very often people who end up with poor credit do so because they are unable to properly manage their fiances. Perhaps this indicates they are also irresponsible in other areas of their life.


It's an awfully big conceptual leap to suggest that people who get into debt and don't pay their bills are also likely to blow up airplanes, now isn't it? Or is "irresponsible" now synonymous with "terrorist"?

If I was going to be a terrorist, I'd make sure I had spectacular credit and not do anything else to stand out from the crowd. Which, I suppose, means that I would rack up $10,000 in credit card bills. Oh well, so much for good credit.

Re:TSA background checks?

[tsvk]

...very often people who end up with poor credit do so because they are unable to properly manage their fiances.

Well, could you tell me then how I can properly manage my fiance.

She's not behaving very well and that is affecting my credit negatively.

Re:TSA background checks?

[wfrp01]

It has to do with statistics.

I think you hit the nail on the head. But here's the question. To what degree do we want our lives to be governed by actuarial accountants? How much can we trust them? Oh, math is math. But let's not let the word "statistics" get in the way of knowing that judgement calls are involved here.

This is really the BIG QUESTION for us all. How do you discern right from wrong? Correct and incorrect? Probable from improbable?

Think about Slashdot's moderation system for a moment. These guys are attempting to separate the wheat from the chaff. Whether they succeed or not, that is the goal. How would you improve on their method? How do you decide whether a statement is bullshit or prophetic?

Until someone can answer these types of questions definitively, I favor giving people the benefit of the doubt. Innocent until proven guilty. Else we are imposing poor judgement on people's livelyhood. Don't send people to jail when you don't really know what you're talking about.

Re:TSA background checks?

[theglassishalf]

...wrong. Bullet holes will not cause explosive decompression. In fact, in an aircraft such as a jumbo jet, there would be NO decompression; the system would just compensate for the leakage.

If you don't beleave me, look up how the systems work.

And yes, I am a pilot.

-Daniel

Re:TSA background checks?

[jackb_guppy]

So my kids are terrorist?

Re:TSA background checks?

[IWannaBeAnAC]

What happens if a bullet hits a window? Or some mechanism inside the door?

Re:TSA background checks?

[mmol_6453]

You end up witha greater airflow through the cabin. large planes are pressurized by ramming the air into the cabin. If more air is leaking out, then they increase the volume of air being rammed in.

Re:TSA background checks?

[IWannaBeAnAC]

Sorry, I simply don't believe you.

Sure, a slow leak is no problem. But a window or door failure is NOT a slow leak, it is a very rapid depressurization! A friend of mine who is an ATC once decribed a flight attendant training film he once saw. On failure of a window at altitude, the first thing that happens is that everyone sitting in that row disappears out the window (whether they are wearing seatbelts or not). People in surrounding rows who are not wearing seatbelts are also in trouble. Sharp pain in the ears as you have a couple of minutes (perhaps less) to struggle to get the oxygen mask on. The pilot is likely to start a rapid descent, scaing the sh*t out of the passengers, who most likely cannot hear anything because of the noise. Need I go on?

Re:TSA background checks?

[Anonymous Coward]

Yes...and so are you!

Only a terrorist would question the government, and its God-given leader, George W. Bush. Only He can smite our enemies and kill the infidels like you and your progeny!!!

Re:TSA background checks?

[Anonymous Coward]

Only terrorists and fifth columnists question the government and/or its Holy-annointed leader, George W. Bush. Neither of these groups deserve equal protection under the laws that my daddy, General Armond Hanz fought the gooks, slopes, krauts, kikes and wops to preserve.

Re:TSA background checks?

[julesh]

very often people who end up with poor credit do so because they are unable to properly manage their fiances.

Yeah. I had a friend who had that problem. She dumped him in the end...

Re:TSA background checks?

[Anonymous Coward]

That's what I find so scary about this. People will be singled out for some serious stuff based on some algorithm that is both secret and probably unintelligible. So much for due process. Yes, I know legally locking me in a room and making me miss my flight while they strip search me isn't a punishment, so due process doesn't apply.

Re:TSA background checks?

[homer_ca]

No, not your kids. If you want me to be more specific. ADULTS with no credit history and whose lack of credit history cannot be explained by circumstances such as recent immigration.

Re:TSA background checks?

[mmol_6453]

Have you ever been on the inside of a jet liner? Personally, I know I'm not small enough to fit through the window. Even lengthwise.

I think your friend was trying to scare you.

Re:TSA background checks?

[IWannaBeAnAC]

I have travelled in aircraft many times.

I agree that it is very hard to fit through a window. Unfortunately, that only means that being forced through one would be rather painful.

For a real example, when a cockpit window blows out, British Airways flight 5390. This link doesn't describe the event itself in much detail, but I do remember that he only survived through a pretty heroic effort by the flight attendants (like, his ankles were severly bruised from where they were holding onto him, all his clothes were blown off, etc). And this was only at 17,300 ft, it would have been much worse (certainly fatal) at 30,000 ft - even if the pilot had not been blown completely out of the aircraft he would have died of hypoxia after a matter of minutes.

See also an interesting article on decompression

I didn't spend long searching, but I couldn't find any real examples of incidents involving bad things happening with cabin windows, I wouldn't be surprised if the worst-case scanario (window blowing out while plane is cruising at high altitude) hasn't happened yet: the biggest danger is when the aircraft is ascending or descending and the pressure difference is changing rapidly. But this is less catastrophic than a depressurization at high altitude.

Missing tech format

[RLiegh]

They went a step further with this experiment last fall with the release of David Weber's War of Honor which had a bunch of novels in html, rtf, doc, palmdoc, and other formats

obviously not meant for technical documents; as I only see rtf, not rtfm format.

Re:Missing tech format

[andfarm]

RTFM is actually a real format under Mac OS X. It consists of an RTF bundled with images, used for readmes and such.

Re:Missing tech format

[rjamestaylor]

Depending on the genre, rtf may be fully descriptive.

[hint]

Bandwidth IS underutilized!

[mmol_6453]

Any RF technician or audiophile can tell you that if you want to focus in on a specific frequency or range, you need good/better AC filters.

For AM transmissions, theoretically a single, exact frequency can suffice. Assuming the transmitter is truly on the expected frequency, all you need is a very narrow bandpass filter.

For FM transmissions, it's a little bit trickier. Simply put, the voltage being applied to your speakers (if one ignores all the fancy equilizer circuitry in a radio) is dependent on the exact frequency being transmitted at a given time. The transmitter sends a constant-amplitude signal whose frequency changes with the amplitude of the audio sample.

With FM transmissions, you need bandwidth. You have to be able to discern between the high and low point in the signal, so your radio technology has to at least be capable of discerning between the frequency at the high point, and the frequency at the low point. The broader the bandwidth, and/or the more precise your transmitter and receiver, the more accurate the signal will be on the receiving end.

The point behind all of this is that we're much better at discerning between frequencies than we were fifty years ago, when the FM spectrum allocated. We should be able to fit a passable transmission in a much smaller bandwidth than we do now.

This has interesting possibilities. If you have stations with a high bandwidth (for audiophiles), mixed with low-bandwidth stations (for simple voice broadcasts, you can allocate your bandwidth much more efficiently.

The same concept can apply for digital technologies, too.

Re:Bandwidth IS underutilized!

[TeknoHog]

> For AM transmissions, theoretically a single, exact frequency can suffice. Assuming the transmitter is truly on the expected frequency, all you need is a very narrow bandpass filter.

No. Mr. Fourier tells us that an AM signal consists of a range of frequencies. A single, exact frequency is just a pure sine wave, it carries no information. The bandwidth required for AM is just the bandwidth of the signal to be carried.

For a simple example, try adding together two slightly different frequencies. You'll get an AM-like signal whose "carrier frequency" is the average of those frequencies, "modulated by" the difference of the frequencies.

Re:Bandwidth IS underutilized!

[mmol_6453]

No. Mr. Fourier tells us that an AM signal consists of a range of frequencies. A single, exact frequency is just a pure sine wave, it carries no information. The bandwidth required for AM is just the bandwidth of the signal to be carried.

I think we're both right...I was referring to the frequency of the carrier wave. The amplitude of the signal (which is also AC) is represented in the number of quanta received per unit time.

The fact that the signal has an AC frequency has no effect on the RF frequency it's being transmitted at.

Re:Bandwidth IS underutilized!

[Anonymous Coward]

If you send a single, exact frequency, all you get at the receiver is... a single, exact frequency. There's no information there. By modulating the amplitude, you are adding information by adding other frequency components to the signal. This expands the bandwidth of your signal as well.

Re:Bandwidth IS underutilized!

[jmorris42]

> For AM transmissions, theoretically a single, exact frequency
> can suffice. Assuming the transmitter is truly on the expected
> frequency, all you need is a very narrow bandpass filter.

Wrong. To send a 1KHz signal via AM you need 2KHz of bandwidth under theoretical best case conditions. You need bandwidth to even send Morse. If you are sending CW at a fast enough speed the bandwidth usage actually becomes non-trivial.

If you can't be bothered to actually study some information theory before opening your butt, at least study and pass a Ham radio exam.

Re:Bandwidth IS underutilized!

[mmol_6453]

No, you need a 2KHz carrier frequency. That's not the same thing as bandwidth. Your signal can't change faster than half your carrier's frequency, since it becomes difficult to discern between your signal's affect on your line voltage and your carrier frequencies, since both your carrier and signal frequencies manifest as AC voltage on your antenna.

Re:Bandwidth IS underutilized!

[Anonymous Coward]

Ok, you're so wrong it's not even funny. Pick up a basic communications theory book. If you have a "perfect" filter, that is, receive only one frequency, you will never pick up anything but that frequency. Pick up only 1MHz, you get a 1MHz tone. The signal that modulates the carrier expands the bandwidth. The previous poster was correct. The bandwidth of the receive filter must be equal to the bandwidth of the modulating signal.

Re:Bandwidth IS underutilized!

[MrTilney]

No, really, you're full of crap. It is bandwidth. The band of the signal in this case is 2KHz wide. Hence the name. Really, put a 2KHz signal on a carrier and look at it in a spectrum analyzer. It'll be 2KHz wide. Please stop commenting if you don't know what the hell you're talking about.

On a side note, just try transmitting at 2KHz. A half wavelength antenna is .5*c/2KHz=150km long.

Re:Bandwidth IS underutilized!

[nathanh]

Any RF technician or audiophile can tell you that if you want to focus in on a specific frequency or range, you need good/better AC filters.

Actually only the RF technician could tell you that. The audiophile would say that AM sounds warmer than FM but only if you're using oxygen-free radio waves. Then they'd start blithering on about how the crystals in their radio were hand-picked by virgins during the winter solstice.

Re:Bandwidth IS underutilized!

[0x1337]

A perfect n-tuned tank circuit which *ONLY* resonates on a given frequency is unfortunately impossible :(

If all else fails - we can revert to Tesla, Hertz and Marconi's spread-bandwith spark-gap/coherer communication :)

Re:Bandwidth IS underutilized!

[Anonymous Coward]

Don't make fun of my obession! It's all I've got, man!!!

*wahhhh* *sob*

Re:Bandwidth IS underutilized!

[istartedi]

I'm sure Lessig is a very capable lawyer, but I wonder what he would say if I asked him who Nyquist and Fourier are. Could he explain the theories for which they are well known?

Re:Bandwidth IS underutilized!

[pe1rxq]

If you transmit a signal with a 2KHz bandwidth on a carrier using AM you get a transmission signal that is 4KHz width (the message is on each side of the carrier in two sidebands). However where you to use Single Side Band (Suppress the carrier and one sideband) You get a 2KHz RF signal.
What is normally called AM has TWO sidebands and thus double the bandwidth of the message.

Jeroen

Re:Bandwidth IS underutilized!

[Hecatonchires]

It just sounds better. Can't you tell?

[Yes, this is a joke]

Re:Bandwidth IS underutilized!

[MrTilney]

Sorry, you are correct. I was actually referring to the previous comment.

Re:Bandwidth IS underutilized!

[jmorris42]

Yup, but why confuse people who are already confused with extra detail? SSB is efficient but until quite recently the difficulty in getting a perfect zero beat rendered it impractical for consumer applications. And now nobody in their right mind would propose a new AM based radio service in this all digital world we now live in. (Even if the bandwidth usage is better and the other problems are all solved tech.)

TSA Data Gathering

[dacap]

Awww. Not so threatening, eh? I was hoping the TSA would go for the whole data collection tamale. Think what happens when the US Gov tries to build a newly designed, big, complex system -- bidding by defense contractors is long, drawn-out, and then it is challenged and redone; the contractor that finally wins takes forever to complete it, if ever; if the contractor actually manages to build something, it's completely unusable; in disgust, the govt throws it away and starts the cycle again with more bidding. Just ask the FAA, LOL!

Therefore urge TSA not to compromise their standards, fellow /.ers. That way we'll have no data collection, ever.

Doors aren't the answer...

[aiken_d]

...secure, locked cockpit doors aren't going to look like such a good idea the first time some terrorist type spends years training to be a pilot and is sitting *behind* that door.

Cheers
-b

Re:Doors aren't the answer...

[user32.ExitWindowsEx]

Well, this system won't stop that either. Think about it.

Re:Doors aren't the answer...

[Mac Degger]

In which case, any other measures you've taken aren't going to help you either.

Re:Doors aren't the answer...

[zulux]

...secure, locked cockpit doors aren't going to look like such a good idea the first time some terrorist type spends years training to be a pilot and is sitting *behind* that door.


Especially now that it's looking like the pilots can will be able to carry sidearms in the future.

The copiolet can lock the door, shoot the pilot and have the plane into the ground in under a few seconds.

Hell, you don't even need to do that - If with an Airbus, just stomp on the rudder hard for a few seconds and and the tail section will fall apart.

Re:Doors aren't the answer...

[evilviper]

Good! Do the freaking background checks on the PILOTS then, not the passengers.

Re:Doors aren't the answer...

[Alioth]

I don't care if he's sitting *behind* that door. It's when he's on the other side *in front* of that door where the problems begin! (Unless you know of an aircraft where the flight deck is in the back).

Galileo Information

[Aaron M. Renn]

As I've long argued, there's no real justification for Galileo. It's about the EU (esp. France) wanting to avoid looking weak next to the US. It is about industrial policy and euro-prestige. There is no reason not to rely on the US GPS system, which already has billions in upgrades planned, including fully separate civilian only signals. The US also has local jamming capabilities that does not require the military to globally degrade signals.

At any rate, there's a lot of good Galileo information on the web. Here are some links:

• http://www.space.com/news/eu_gps_020326.html.
  
• http://www.ucis.pitt.edu/cwes/EUC/EUC_Research/Pol itics_of_Galileo/politics_of_galileo.html
  
• http://www.galileosworld.com/galileosworld/
  
• http://www.state.gov/r/pa/prs/ps/2002/8673.htm
  
• GPS http://ifen1.bauv.unibw-muenchen.de/Lehre/External /SpaceTech/GPS.pdf.
  

These links are from a file I have of info on Galileo. Hopefully no link rot.

Re:Galileo Information

[Anonymous Coward]

Trusting the US govenrment is not high on anyone's priority list....

Re:Galileo Information

[Anonymous Coward]

These links are from a file I have of info on Galileo. Hopefully no link rot.

Well gee, you could, uhm, maybe TEST THEM BEFORE POSTING THEM? You have five links there, it wouldn't be that hard.

Re:Galileo Information

[ergo98]

There is no reason not to rely on the US GPS system...

Really? I would beg to differ. I say this under the context that the US taxpayer bought and paid for the GPS, so they have no duty to guarantee any level of service, however some of the arguments against a European GPS system seems to be along the lines of the kid who's taking his ball home and gets angry when he sees that they got their own ball.

Political sidenote: I love how the administration has set up a whole slew of ridiculous propaganda techniques to give the illusion of a dangerous enemy to enrage the public into a president supporting, pollster responding public. Want to invade someone? Up your dubious "threat level" as if you are responding to some overt immediate threat from the deadly enemy. Want to pretend that your enemy is more powerful than they really are? Talk about disrupting GPS, lest they guide their 1960s era Soviet T55s by it... Eurasia...europa...who knows anymore. I am making no comment about the righteousness of this war, but I hope that people can see through these shallow manipulations.

Re:Galileo Information

[Aaron M. Renn]

The US did not degrade the GPS signal during the Afghanistan conflict. With emergency services such as cellular E-911 relying on accurate GPS, I think it's unlikely the US would likely degrade the signal. (Now watch them turn it down 30 seconds after I post this....) Keep in mind, even with Galileo, the US military would doubtless jam the signal if they felt their battlefield superiority was threatened.

Re:Galileo Information

[Mac Degger]

Yeah...I mean, imagine a GPS signal which is 4 times as accurate, and gives you an error margin to boot. And it's a system which doesn't have a built in inacuracy for the public, and won't be changed in accuracy whenever someone wants to have a war, thus making it safe for missioncritical applications (like airtravel, all year round surveying etc).

Nah, an obviously inferior system, made by people who are jealous of another counrty. It couldn't have anything to do with a part of the world wanting a better system soonest, while fostering a quite handy knowledge base.

I bet you lost that long argument, didn't you?

Re:Galileo Information

[pseudochaotic]

Eurasia...europa...who knows anymore. No, no. We're at war with Eastasia now.

Re:Galileo Information

[nexex]

whoops we already beat you, sorry.

get a waas capable reciver, >3m accuracy.

http://www.garmin.com/aboutGPS/waas.html

Re:Galileo Information

[farnz]

Make it work in Europe, Africa, the Far East, Australia, anywhere beyond America, and you might have a point.

Until then, a better GPS for the world is a good idea; if nothing else, two systems means that if one fails, the other is still useful.

Re:Galileo Information

[Mittermeyer]

I agree that Europe would do well to have it's own system for the reasons you mention, but they BETTER be able to degrade it at will, otherwise attackers will be able to build Galileo-driven targetting systems and cruise missiles will be able to hit European targets using their own satellites.

As far as anyone else using them against us is concerned, we'll just jam the Galileo frequencies in our AO. Americans would be advised not to buy Galileo handsets because we may have to set up jammers for all non-GPS constellations.

Re:Galileo Information

[ergo98]

I agree that Europe would do well to have it's own system for the reasons you mention, but they BETTER be able to degrade it at will, otherwise attackers will be able to build Galileo-driven targetting systems and cruise missiles will be able to hit European targets using their own satellites.

Because terrorists have cruise missiles? Nah, they'll just drive a truck full of fertilizer out front (and they'll get in the country via the airports legally, as the 9/11 bombers did with the US): No need for GPS for that. Of course for conventional war that's why there are lots of international agreements and such: First World nations tend to not go to war with each other anymore, which is why most have such an aversion to war. (Although it tends to be that those who know war the least are the most hungry for it).

As far as anyone else using them against us is concerned, we'll just jam the Galileo frequencies in our AO. Americans would be advised not to buy Galileo handsets because we may have to set up jammers for all non-GPS constellations.

Who, exactly, is going to attack the US homeland with Galileo directed devices? In any case, I wouldn't at all be surprized if the myopic, xenophobic administration did just such a trade-barrier under the guise of "Homeland Security", just as they've eroded personal liberties.

Re:Galileo Information

[Mittermeyer]

Yes it is more likely that a container nuke or truck bomb will be the likely vector of attack. Nonetheless plenty of other nations are gaining the capability to build cruise missiles, and would be more then happy to build their guidance by using Galileo. We also have allies that can be attacked by such weapons, and have an interest in being able to protect them.

Who would have these cruise missiles and use them? Well for starters China if they attack Taiwan and we help defend it. They may not attack us directly but they would attack Guam and possibly the Panama Canal.

I am afraid I cannot agree with your thesis re: First World nations- WWII was within a generation of WWI and the horrors of the Great War did not serve as a deterrent.

TSA vs. FOIA

[NOLAChief]

IIRC, government-held info that's supposed to be purged from someone's record has a nasty tendency to stick around (whether by accident or by design). I wonder how hard the TSA and the DHS will make it to submit a FOIA request to verify that this information *is* being purged after each flight.

I agree with many Salon responses to rx spectrum

[LM741N]

As an RF/Microwave Engineer, I deal with the problems with RF interference daily. A recent article I saw online lauded the participation of ham radio operators in disaster situations including the World Trade Center relief operation.
Imagine thousands of devices and gadgets emitting radiation on random frequencies, and you can see the problems that might arise in critical communication situations. The background noise level at HF frequencies is already very bad due to consumer devices. I would hate to see it get any worse.

EGNOS != GPS

[ByTor-2112]

EGNOS is the European answer to WAAS, folks, not GPS.

EGNOS isn't GPS

[fruity_pebbles]

EGNOS is the EU's equivalent of the FAA's WAAS. EGNOS and WAAS are systems that supplement GPS by providing corrections (thus giving higher accuracy) and integrity monitoring, so a GPS receiver will be informed if a GPS satellite is outputting bad data.

EGNOS is only available in Europe at the moment because it's only being transmitted from one geostationary satellite that's sitting over Europe. WAAS is currently being transmitted from two geostationary satellites over the Americas.

Neither system is what I'd call new - they've been in a sort of beta test phase for years, and there are already consumer receivers on the market that support EGNOS/WAAS.

Re:EGNOS isn't GPS

[ByTor-2112]

Mod this guy up, he actually posted the details that I was too irritated to bother with.

Do ANY of you slashdotters actually know anything about the technology you harp about? Or maybe check the URL's...

Re:EGNOS isn't GPS

[GoRK]

Also of note, there is a european answer to GPS called Galileo, but it's really not moving very fast, and won't necessarily be any more accurate for civilian use than GPS is for civilian use.

Re:EGNOS isn't GPS

[mmol_6453]

Geosynchronous satellites have to orbit around the equator...

Re:EGNOS isn't GPS

[cymen]

Well you do, right? Jeeze... Sometimes it is too easy.

Re:EGNOS isn't GPS

[Anonymous Coward]

"WAAS is currently being transmitted from two geostationary satellites over the Americas"

That's close enough, but these satellites are called WAAS-AOR and WAAS-POR because they are over the Atlantic and the Pacific (Ocean Regions). They are actually Inmarsat satellites, also mainly used for maritime communications. WAAS is just an added service.

Re:EGNOS isn't GPS

[Anonymous Coward]

Some do but all evidence points to moderators generally don't. All threads on GPS here and earlier show with painful clarity that those modded "Insightful" frequently are wrong.

If this forum is to retain some value I hope moderators can limit their use of "Insightful" to topics they actually know enough about to truly determine is insightful as opposed to wriiten lucidy but wrongly.

Re:Looks like it's only usable in Europe for now .

[OS2_will_prevail!]

Perhaps I just don't get it, but I am having trouble figuring out why anyone (outside of a small subset of the population) would need accuracy less than 50 feet or so. I suspect people that really need accuracy greater than this currently have the tools to achieve such accuracy. It's not like most people are letting their GPS device drive their vehicles or something. Plus for people that need better accuracy, there are means by which to get it, depending on how much you want to spend.

But, as I said earlier, perhaps I just don't get it....

Dear Sir,

[Anonymous Coward]

Boo-fucking-hoo.

Sincerely,
Slashdot

Re:Looks like it's only usable in Europe for now .

[Anonymous Coward]

Agreed. Clearly only terrorists would want anything with an accuracy better than 50 feet.

Data rate is proportional to bandwidth.

[Christopher Thomas]

For AM transmissions, theoretically a single, exact frequency can suffice. Assuming the transmitter is truly on the expected frequency, all you need is a very narrow bandpass filter.

If you try to send an AM signal across a 1 Hz band, you will get a 1 Hz bandwidth signal out at the other end. Not very useful if you were trying to play music. Definitely not useful if you were trying to transmit data.

The number people are interest in is data rate. Data rate is bandwidth times the log to base 2 of the number of levels you can distinguish. Different encoding schemes (FM, wide-spectrum coding) express the relation differently, but the same limit applies.

You can narrow the bandwidth, but as soon as you hit noise limits, your data rate starts going down too. *That's* the problem. Low-noise electronics doesn't help if the noise is from other users.

The only way to avoid user clutter is to switch to something other than a broadcast system, which involves either large dishes or short-range transceivers and hubs connected to a _wired_ backbone.

Re:Data rate is proportional to bandwidth.

[DShard]

This is assuming no triangulation of source. If I treat my input as a point, I get interfernce at any given frequency because I treat all transmission as coming from and arriving to this imaginary space. (this is the way traditional broadcasting is treated)

If on the other hand I treat my input as a three dimensional space all of a sudden I can have as many broadcast sources as my ability to process them can tolerate. I can distinguish signal based on directionality, though I have new concerns like multi-path signals and two sources coming one behind the other.

It is true that bandwidth is a high school math problem to figure out for a given source, but it is a technological problem why we have interfernce.

Re:Data rate is proportional to bandwidth.

[Christopher Thomas]

This is assuming no triangulation of source. If I treat my input as a point, I get interfernce at any given frequency because I treat all transmission as coming from and arriving to this imaginary space. (this is the way traditional broadcasting is treated)

If on the other hand I treat my input as a three dimensional space all of a sudden I can have as many broadcast sources as my ability to process them can tolerate. I can distinguish signal based on directionality, though I have new concerns like multi-path signals and two sources coming one behind the other.

If you have a receiver that is smaller than the signal wavelength (i.e. is an omnidirectional point receiver, moving or non-moving), you will end up not having enough information to disambiguate sources when the system is beyond the capacity limit that I outlined previously. This is easy enough to demonstrate; the total amount of information available to you is the amount that one transmitter could produce, assuming that signal generation and reception fidelity are equivalent. Trying to distinguish between multiple sources dumping as much information as they can into the environment requires pulling extra information out of nowhere, which you aren't able to do.

Knowledge of the location of the sources, or of where signal-affecting surfaces are in your environment, or of the motion of your receiving unit (for synthetic aperture tricks) makes signal processing easier when you're below the saturation point, but doesn't help you when the total amount of information you're trying to extract is greater than that received.

If you feel I'm overlooking something, then let's consider an artificial case that's easy to analyze. Assume straight sampling of signal data from zero to a given frequency with a given number of detectable data levels (linear for easy analysis). Assume sources and receivers are point sources (which they are if they're smaller than a wavelength). Do whatever you like with the environment and with data processing, and show me how you'd get one receiver to reconstruct the continuously-streaming signals from two sources.

If there's a way to do this, great; I'll have learned something today. If you feel that it is only possible by changing one of the problem constraints, we'll negotiate (IIUC it's only possible by changing the problem to make the total data received at least equal to the total data transmitted, by any of a variety of means).

Re:Looks like it's only usable in Europe for now .

[ergo98]

I believe the claimed accuracy is 5 meters.

Cheers!

Re:Looks like it's only usable in Europe for now .

[Carl Drougge]

Where does that 5cm number come from? It says 2m in the swedish text, and 5m in the english text..?

(1m = 100cm, for those who find the decimalness of the metric system confusing)

that's pretty shortsighted

[DrSkwid]

2 bits are enough for anybody

Re:that's pretty shortsighted

[OS2_will_prevail!]

2 bits are enough for anybody

1 bit is plenty thank you. On or off, what else is there?

Re:that's pretty shortsighted

[Anonymous Coward]

On, off, or not yet observed.

Re:that's pretty shortsighted

[DrSkwid]

I was thinking in pseudo-physical terms where 1 and 0 are two bits

i don't know why I was but i was

Re:that's pretty shortsighted

[OS2_will_prevail!]

I was thinking in pseudo-physical terms where 1 and 0 are two bits

Then we are in agreement! ;)

Re:that's pretty shortsighted

[Nicolas MONNET]

Some people are that binary: "you're either with us or against us."

That kind of people is rather harmless when they get drunk, but as soon as they stop they start harassing random people.

Re:that's pretty shortsighted

[desdemona]

THere are 10 types of people: those that get binary, and those that don't.

Re:that's pretty shortsighted

[DrSkwid]

there are 10 types of people

those that get trinary
those that don't
and some other lot

Not so bad on Lessing.

[Erris]

Most of the letters, but one or two bizare ones supported Lessings basic thesis. Tom Rouch has this offensive comment for Salon:

It would be much more productive if Reed and other "architects of the Internet" spend time finding solutions to EM pollution caused by switching power supplies and digital systems, rather than proposing ways to make problems worse in areas they clearly don't understand.

This comment follows a rant which ironically ignores most modern radio breaktrhoughs: packet routing and frequency hopping on low power devices to create a network with far greater bandwith than a single transmitter per frequency set up that's current. Instead, he focus on ancient details of antenae size and signal propagation. It's amazing that someone could ignore the demonstrated reality of Alohanet and 802.11B meshworks and then call others ignorant.

Then again a simple search pulls up stuff about Tom Rauch. Is this guy a profesional slammer or what?

• Some strange blow up over RF amps in the early 90's
• Another Amplifier blowup.
• Interesting tube rant.

Well, fine, he knows his tubes and amps, IF the first person linked to above is not correct in assesing him as a whore. You have to be suspicious of people who rant so.

All of the other letters on that page supported Lessing's conclusion that the broadcast spectrum is poorly allocated and mostly empty. There was that one bizare and false analogy to a pinhole cameras with no pinhole. I've never seen a pinhole radio, it must be intersting.

Re:Not so bad on Lessing.

[Christopher Thomas]

This comment follows a rant which ironically ignores most modern radio breaktrhoughs: packet routing and frequency hopping on low power devices to create a network with far greater bandwith than a single transmitter per frequency set up that's current.

Mesh routing schemes break down in highly populated areas - you end up with too many messages needing to be routed by any given node, and the fraction of node bandwidth used for that node's messages dropping like a rock.

Relation is a fun exercise in calculation that takes about 2 minutes.

The only way around this is to link to a backbone and strongly limit transmitter power, which sort of torpedoes the "let's stop regulating the spectrum" argument.

You can do point-to-point without a backbone, but only with a large dish or a large *wired* array of transceivers.

how many?

[Anonymous Coward]

how many lives per gallon are you getting america?

That's a very good question. How many lives should we be getting? If it's under ten, I've got no problem with that. Anything over that would make me consider downgrading my Lincoln Aviator to something more sensible like a Ford Excursion.

Four or five lives for me to drive down to the grocery store? Hell of a deal, I say! What do you expect me to do, walk?!?!?

I'm sure if these people in Arabia or whatever the hell it is could feel the supple leather of my seats or the raw power of America's finest sport utility vehicle, they'd be more than happy to trade their lives so I could ride in style. I don't understand those people anyway, living in huts and raising camels. I don't see how their poor real-estate buying choices are my problem. If they don't like it there, they can just move, can't they? Not move here, of course, this country is far too crowded and our resources are too limited. But isn't there some country where they could go and buy a nice villa? Surely there must be.

It's not like we didn't tell them, "leave the city, we're going to be dropping some bombs." They had plenty of warning! I just don't understand what they're complaining about.

Re:Looks like it's only usable in Europe for now .

[mmol_6453]

It's not like most people are letting their GPS device drive their vehicles or something.

No, but they let Microsoft Streets do it for them. And it's really annoying when your car symbol jumps from one street to a parallel one.

Anyway, check out Geocaching. It's awesome, but an accurate GPS helps out a lot. You go around finding boxes of prizes with only a GPS coordinate and a couple of clues. It's great for excercise, and it's fun! You hear me, geeks? FUN EXCERCISE!

Re:Looks like it's only usable in Europe for now .

[mmol_6453]

+/- 32ft is the normal disclaimer my GPS gives me...It gets down to 16 ft in a good coverage area. (i.e. not under a bunch of tall trees, or in a concrete building.)

Radio Spectrum Underutilized

[digitaltraveller]

Currently there are three ways to partition the available spectrum:

FDMA (Frequency Division Multiple Access): The standard technique of TX/RX on different frequencies (or colors if you read the analogy on Slashdot a few days ago). Ho-hum, it's the first thing I would have tried too. Our predominate and most wasteful technique.


CDMA (Code Division Multiple Access): A set of spread-spectrum techniques that use a sort of RF kung-fu to manipulate previously considered undesirable properties of radio waves to advantage. On the coolness factor the engineers that designed these technologies should be in the nonexistant Engineering Hall of Fame. The scuttlebut is that some of this technology was invented by Qualcomm as early as WWII but was highly classified until recently, so Qualcomm still holds most of the patents to this today.


TDMA (Time division multiple access): This involves standard unix-like time splicing, except using radio signals. GSM works like this by partitioning groups of eight consecutive time slots to form a TDMA frame with a duration of 4.615 ms. Each transmitter (cell-phone) in the area gets one burst period (a slot) of duration 15/26 ms (approx. 0.577 ms) to use the channel. This is an immensely powerful technique, and one that is infinitely scalable. It's only limitation is the speed of our electronics, which can and should maintain it's exponential speed curve. This is why the spectrum is underutilized.

Re:Radio Spectrum Underutilized

[Christopher Thomas]

[TDMA] is an immensely powerful technique, and one that is infinitely scalable. It's only limitation is the speed of our electronics, which can and should maintain it's exponential speed curve.
This is why the spectrum is underutilized.

You do realize that as sampling rate goes up, spectrum use (bandwidth) goes up, right?

Any given region of spectrum can only carry so much data, any way you slice it. Power, noise/clutter, and bandwidth combined determine (and limit) data rate.

Re:Radio Spectrum Underutilized

[CBravo]

>Any given region of spectrum can only carry so much data, any way you slice it.

I'll slice you a vector. Maybe you should rtfa before saying this because that is what the article is about.

Re:Radio Spectrum Underutilized

[Kunta Kinte]

Currently there are three ways to partition the available spectrum.

CDMA's and CDMA hybrids are being used in favor of the others. Everyone's doing CDMA now.

Checkout http://www.astalavista.com/mobile/wct.shtml for a longer list.

Re:Jim Tyre is a fine human being

[Anonymous Coward]

Absolutely. Garrison Keillor is a fucking weak hack. You should go kick his listener supported ass.

not Lessig : it was David Reed / David Weinberger

[DrSkwid]

it's :
The myth of interference
Internet architect David Reed explains how bad science created the broadcast industry.

- - - - - - - - - - - -
By David Weinberger

Re:I agree with many Salon responses to rx spectru

[Remik]

You misunderstand the arguement. The frequencies are far from random, and the equipment is designed to expect frequency hoping, amongst other things. That is the most basic step toward a better utilized spectrum, one that has been used since WWII.

-R

Too Cool.

[joejoejoejoe]

The kicker is the recently released Slashdot plugin, which allows authentication of Windows clients with... yup you guessed it, Slashdot Accounts!

Heh, i read the blurb, not the article (yet) but hell, THIS KICKS ASS!

My useless slashdot account is no longer so useless. Can I have a fake email address to link stuff to and have the messages sent to my useraccount on this site?!??!?! With the ability to respond? Ok, Ok, Ok, I guess i want joejoejoejoe@slashdot.org! Yeah!

Free Email, there has to be money in there somehwere to make it worth while. ;)

This means ... what?

[A nonymous Coward]

Are we gonna run credit checks on the pilots too?

Re:Looks like it's only usable in Europe for now .

[norweigiantroll]

You've obviously never tried to find a geocache hidden in a field of boulders and rocks. Look for an hour or so and you get pretty mad.

EGNOS enhances GPS, doesn't replace it

[RevLimiter]

EGNOS is the European version of WAAS, a system that enhances GPS accuracy by providing differential corrections (like DGPS, only from a satellite instead of a ground-based transmitter).

It's currently in testing, and is expected to be turned on for real soon.

See http://gpsinformation.net/waasgps.htm

Aldenata OGL D20 RPG on the disc & on the web

[Robotech_Master]

One noteworthy thing about the CD-ROM that's not mentioned in that orientation is that it will include a (partly-)OGL D20 RPG based on the Aldenata books, which you can currently find hosted in rich text form at Alldenata.net under the link marked "rules." (I'm not entirely sure why the spelling of the aliens changed between the first few books ("Alldenata") and the most recent one ("Aldenata"); nobody on the John Ringo Baen Bar group seems to want to talk about it.)

Re:I agree with many Salon responses to rx spectru

[MrTilney]

Yes, and if you want to redesign and replace every radio on the planet, using technology that is significantly more expensive, or doesn't even exist yet, be my guest. But you have to replace my TV with the $20,000 frequency hopping spread spectrum one.

Also frequency hopping spread spectrum was designed to stop jamming since it's hard to broadcast across a very wide spectrum at high power. But give one of these transmitters to everyone in a metropolitan area and watch the mayhem insue. All cell networks use spread spectrum technology, and there are still subscriber limits.

RTFA!

[MrTilney]

Please read the original article before you attack the character of people who put their real names in the reply. The pinhole camera thing came right out of the article, and highlighted the gross lack of technical knowledge of the author. College freshmen in physics and engineering know that radio waves interfere. It's the basis of quantum mechanics.

The reply of Rauch was completely accurate. I'd like to see you send any signifcant power at modern radio or TV frequencies without a giant antenna. Mesh networking may be nice, but what happens when you're alone on a back road with your .1W transmitter that can send 100m? And, it still doesn't change the fact that all of the technologies that you mentioned are incompatible with existing technologies.

Let the people who have EE and not CS degrees build the radios. Real life is not digital.

Re:RTFA!

[dlakelan]

So what you're saying is that the reason we can't move forward with radio technology is that people in the back woods will have no way to watch "Must Miss TV" (TM)?

The sheer failure to grasp the concept is so amazing to me. Even the geeks don't get it.

1) Open up some portion of the spectrum to unlicensed transmitters that are limited only by reasonable health concerns and basic mode of operations limits(ie. a few watts effective radiated power in the UHF band with "minimal required output power" type regulations).

2) Allow modern economics, silicon engineering, and market demand factors to create useable mesh communications technologies, software defined radios, and software defined directional antennas.

3) Sit back and reap the rewards of human ingenuity.

Outside of the bandwidth assigned for unlicensed use you will not see interference due to the requirements that the devices not generate it.

When we have enough experience and/or have created a system that truly offers reliable communications without the need for pre-assigned frequencies, then we can completely remove all frequency assignments and recover all the spectrum

The RF engineers that jump on people's back about antenna sizes and power outputs and distortion and soforth are stuck in their tunnel vision that the future will look just like today.

The futurists (Lessig, Reed, etc) publishing in a venue like Salon are not supposed to spell out the nitty gritty details of each step along the way, they are supposed to show us where we should be headed. I'm apalled that even the geeks can't take the ball and run with it.

As for radio waves "interfering" they create a superposition, but that superposition is different at different locations. You are assuming that these radios will be stupid and have antennas at a single location. With several antennas seperated by even short distances combined with motion on th e part of some stations, and reflections, you can recover a tremendous amount of information from multiple sources.

Re:RTFA!

[MrTilney]

From you blatently simplistic arguments, I can see that you suffer from the same ignorance of actual communications theory as the author of the Salon article.

First, people are already doing exactly what you say. Bluetooth, 802.11a,b,g and other technologies operate on unlicensed bands. However, you may notice that you're 802.11 performance sucks if someone near you uses a microwave.

Second, different frequencies have different propagation characteristics in the real world. There is some scarcity, it's not fake. CDMA cell phones use all kinds of spectrum reuse techniques, and they still interfere with each other.

Third, the smart antenna argument, is being used by the lazy geeks who "don't get it". But it's not exactly cheap or easy to implement. Furthermore, for the frequencies used today, it isn't very applicable because the spacing is larger than your average cell phone. That's why it's used in cell phone base stations and those cool WiLan array base stations.

And finally, yes, some people want to send signals farther than 100m. That will take real power, and interfere with all of your "mesh networks."

If you think you can fix it, take some damn communications classes. Build one of these "smart radios." Then you'll see what the problems are.

Re:RTFA!

[dlakelan]

I have had an amateur radio license since 1989 and have my share of communications and radio frequency theory.

WiFi is just the barest beginning and restricted to as you say a propagationally challenged spectrum.

The point that you have missed is that the investment required takes economic incentive that doesn't exist in the current regulatory structure.

You have missed the point that at first "we" want our own band with good propagation that won't interfere with current usage. One good example would be unused UHF television frequencies, most of these are unused in most areas, and it would be relatively simple to detect them and not interfere.

The fancy multi-array antenna systems and mesh protocols will come a lot faster when it's possible to sell 160 million units a year unlicensed.

Once they come, the current users will migrate away from their outdated broadcast technologies VOLUNTARILY because the new technologies will offer so much more... And if they don't so what...

Re:RTFA!

[MrTilney]

I'm not making the argument that new technologies shouldn't be researched, or that the current regulatory scheme is correct. This thread started because someone made some very ignorant and mean statements based on an article that was highly flawed. I was simply trying to state that the "the FCC is a relic of old thinking" crowd overstates things.

And, personally, I think we should stick them on an airplane with some very powerful wideband transmitters. Over the ocean, though.

Re:FP

[YOU LIKEWISE FAIL IT]

Whoever you are, you've made me very proud.

*wipes coke off keyboard*

YLFI

Its easy to find uses for high accuracy.

[MyNameIsFred]

While the subset of people that need high accuracy maybe small, that doesn't mean they're not economically significant. Just making surveying easier would be a hugh cost savings. Think of all the things that are surveyed. The lot your home sits on. The street in front of your house. In oil exploration, there's surveying of seimic sensors. The list goes on and on.

Re:Its easy to find uses for high accuracy.

[OS2_will_prevail!]

While the subset of people that need high accuracy maybe small, that doesn't mean they're not economically significant

Certainly I would agree with what you say. I am fairly familliar with paying surveying bills, so lessening them would be a help. However surveyors will not be using handheld Garmins to do their work anytime soon. (Indeed, I do not believe that GPS data is valid for a legal survey)

I suppose that the intent of my original post was twofold.

One, to ask the honest question of why would Joe/Jane Average need 5cm accuracy from a GPS device. I must confess ignorance on this. (Although I am learning, I have been refered to geochaching twice now.) While Selective Availability might be problematic for that, it is certainly not the end of the world.

And two, to state that people that require accuracy will not be affected by the reinstatement of Selective Availablity. WAAS, the Coast Gaurd, and others provide differential signals to get GPS recievers into the sub-meter accuracy range, and since these systems were created under SA in the first place, they should be unaffected. Indeed, as I saw on this link (I think) that was posted with the comments on the original story, there are methods of using the military's own encrypted differential signals to increase accuracy, and I doubt the military is going to fool with their differential signals anytime soon. I suppose I should turn off the blockquote now...

As an aside, while I never surveyed for a profession, I did learn (kinda) how to do it back in college. I always thought it would be rather fun to go find the "iron pin located 2 chains NW of a big oak tree" that was driven there 150 years ago or so....I am sure that if I did that for a living, I would find that quite dull.

In summary, I fear that I did not express myself properly in my original post. It is not the first time, I fear. (as hard as that is to believe!)

Re:Its easy to find uses for high accuracy.

[hughk]

However surveyors will not be using handheld Garmins to do their work anytime soon. (Indeed, I do not believe that GPS data is valid for a legal survey)

It depends on what you mean by legal. I know people who lay roads by GPS. The receivers they use for benchmarking (the key anchor point for a survey) are static things. A true survey benchmark is a point which has been extremely accurately located. The alternative to benchmarks (which are normally in built up areas) are trig points (also located down to the mm level). There are many cases where these benchmarks are just not available, so reliance is made on a GPS reference station.

They have used SA signals before, but the average out the errors by waiting for multiple sattelite passes. In the end it is down to cm level. After the benchmark, surveying uses mostly optical techniques. This is slow. I do know that some people have used multi-pass GPS to establish a local DGPS signal to give corrected signals to portable receivers.

Handheld GPS doesn't go to the cm level at the moment. It will do, but not with the current GPS satellite system. Backpack systems can and do. For example, some of the searchers for the Columbia debris were using the backpack units to fix the location.

Please, do some research once in a while

[MrTilney]

Where the hell do you get your info?

Most modern radios (I mean those in cell phones/WiLan) use a combination of these techniques. Furthermore you have a serious lack of understanding of the technologies you mentioned.

First, CDMA is considered on the forefront of spread spectrum technologies today, TDMA is old-hat. Second, TDMA is not infinitely scalable. If you have shorter time slices, you increase the bandwidth. There is no free lunch, you have to use bandwidth to send data. You can sometimes increase efficiency, but nothing is infinitely scalable.

Really, put the infinitely scalable TDMA system in the engineering hall of fame with the perpetual motion machine and brickwall filter.

Re:Please, do some research once in a while

[WolfWithoutAClause]

TDMA is old-hat.

Yes, but not necessarily worse for that. WiFi uses it, as does ethernet for that matter.

Second, TDMA is not infinitely scalable.

True, and false ;-)

True in the sense that sending more bits between two nodes increases the frequency band used, and eventually the band interferes with surrounding bands.

However, if power control, node routing and directional antennas are used the network throughput scales up proportional with the number of users; and TDMA supports this.

Re:Please, do some research once in a while

[MrTilney]

Quite right on all fronts.

I was simply trying to dispel some of these myths that the communications ignorant seem to be propagating.

Many older technologies are still in wide use. Also, power control, node routing, and directional antennas will improve just about any point-to-point communications.

This will ruin my karma, but...

[john.r.strohm]

The statement about AM is flat-out wrong.

Do the fscking trig.

Consider a sinewave modulating signal. Let c be the carrier frequency, and m be the modulating frequency. Recall that cos(u) varies between -1 and 1. We want the modulating control signal to vary between 0 and 1, so the modulator is 1/2(1+cos(m)).

We use cos(u) because it simplifies the key trick in the derivation. OBVIOUSLY, it is just a phase shift to do it in sin(u).

Then the fundamental equation of AM is

f(t) = 1/2(1+cos(m))cos(c) (1)
= (1/2 + 1/2cos(m))cos(c)
= 1/2 cos(c) + 1/2 cos(m)cos(c) (2)

The first term is the carrier wave. Observe that it carries half of the input power and NONE of the modulating signal.

Recall from basic trig

cos(u+v) = cos(u)cos(v) - sin(u)sin(v)
and
cos(u-v) = cos(u)cos(v) + sin(u)sin(v)

Then
cos(u+v) + cos(u-v) =
(cos(u)cos(v) + cos(u)cos(v)) +
(sin(u)sin(v) - sin(u)sin(v))
which simplifies to
cos(u+v) + cos(u-v) = 2 cos(u)cos(v)
Or
cos(u)cos(v) = 1/2(cos(u+v)+cos(u-v))

That looks familiar. Recall (2)

f(t) = 1/2 cos(c) + 1/2 cos(m)cos(c) (2)

Substituting

f(t) = 1/2 cos(c) + 1/2(1/2(cos(m+c)+cos(m-c)))
= 1/2 cos(c) + 1/4 (cos(m+c) + cos(m-c))

And there you have it. You have a carrier wave, and you have two sidebands, and the bandwidth of the whole thing is twice the modulating frequency.

The next step is to observe that the Fourier theorem applies and is carried straight through, and so ANY modulating signal will generate two sidebands, one above and one below the carrier wave, each preserving the harmonic content of the modulating signal, but with one reversed in frequencies.

Your explanation of FM is just as bad. I'm not going to do the derivation, because it is MUCH messier, involving very ugly Bessel functions, and I don't have my textbook handy.

You can reduce the bandwidth of an FM signal, but you lose fidelity.

You can reduce the bandwidth of an AM signal by band-limiting the input audio information, which is routinely done in voice communications gear: the full audio spectrum goes up to NOMINALLY 20 kHz, but the useful speech formants are pretty much all found between 300 Hz and 3 kHz.

You can suppress the AM carrier wave, and you can suppress one of the sidebands. This is also routinely done, in single sideband communications. This involves loss of redundancy and loss of easy tuning, which in turn makes careful tuning much more important: any mistuning comes out as distortion.

Re:This will ruin my karma, but...

[Anonymous Coward]

Interesting. So when you show genuince evidence of factual knowledge and can show the nitty gritty technical details (this is news for nerds, right?) you get modded no higher then 4.

Re:Looks like it's only usable in Europe for now .

[OS2_will_prevail!]

You are correct. In fact, I had no idea that there was any such thing as geochacheing until this very moment. From visiting the website, it would appear that it is supposed to be at least somewhat difficult? Thusly, less accuracy should make for more fun?

In all seriousness, it says much for the state of humanity when we can engage in such things due to the availabilty of free time. We're not so bad off after all I suppose. (Not that I begrudge geocachers, I do stupid things with my freetime as well.....like read /. )

Re:Looks like it's only usable in Europe for now .

[Mac Degger]

RTFA. Sorry, but RTFABetter :). It states that this system is a precursor to Galileo, the worldwide system, but that this is in place above Sweden (and thus as you said available only in part of Europe).

But yeah, it is sweet...and that's 2 meters (according to the swedish text as oposed to 5 meters in the english text...strange, that)PLUS an estimate of error in the reading (which could be 0.001 mm or 1 meter :)

Missed one Re:Radio Spectrum Underutilized

[WolfWithoutAClause]

There's also have a sort of space division multiplexing- i.e. using directional antennas. That concept is used on TV aerials among others.

Re:Looks like it's only usable in Europe for now .

[Anonymous Coward]

Regarding availability; read the text! It says:

EGNOS will achieve its aim by transmitting a signal containing information on the reliability and accuracy of the positioning signals sent out by GPS and GLONASS.

So EGNOS works rather like WAAS. They provide corrections to the GPS signal. How do they obtain the corrections? A network of fixed ground stations with precisely known positions receives GPS, compares the GPS position with the actual position, and computes GPS corrections. Those corrections are beamed up to a satellite, which beams them back down for appropriately configured GPS receivers to make use of. The GPS receiver looks at the corrections for nearby ground stations, and linearly interpolates a correction for its location.
The accuracy of such a correction depends on the density of ground stations (the nearer you are to a ground station, the more applicable its correction signal). The coverage area is wherever the administrators decide to sprinkle their ground stations. Presumably EGNOS will limit their ground stations to Europe, but in principle they could put them everywhere. So it looks like EGNOS is just WAAS for Europe.

Re:I agree with many Salon responses to rx spectru

[Remik]

The evidence is out there, the technology is feasible. What is being suggested is that wireless spectrum be given the same chance that the wired network received, an end-to-end arrangement with the smart technology on the ends and an essentially stupid network.

It worked for the wired internet, why can't it work for wireless?

-R

!logic

[spankus]

GPS has spawned a 12 billion dollar a year industry, it is relied upon solely for navigation in numerous countries without the ability to develop rudimentary navaids, and it helps broadcast american goodwill worldwide.

Capitalism dictates that GPS will never go away

The only people I'd opt out of GPS are the French.

Re:!logic

[torpor]

Capitalism also dictactes that there will be competing standards, and in this light, I say bring on the EuroGPS!

Lord knows, the backwash from drinking American coolaid is harsh enough as it is without them futzing with GPS along the way ...

GPS: The New WoMD!

Re:Looks like it's only usable in Europe for now .

[SimonInOz]

You've never been sailing, have you? In the fog ... Try it some time - you might suddenly get to appreciate the advantages of accuracy.

Or you could try flying - in poor viz.

But I agree, you just don't get it.

Most Important Use for High Accuracy

[oldCoder]

The most important use for high accuracy is in targeting weapons by GPS, what the US Air Force is doing in Iraq this very day...

Thanks to Moore's law, it won't be long before we'll able to convert a street address to coordinates, and feed those to our robotic model airplane (or RPV) and drop a load of semtex on the house of the guy who cut us off in traffic the other day. Take that! you arrogant bastard!

Fortunately, the day is coming soon when maybe 30 countries (and perhaps their terrorist proxies) will have nuclear weapons, which, combined with a good navigation system, means the human race won't have to worry about navigation for too much longer. We'll be extinct.

Re:Most Important Use for High Accuracy

[hughk]

The most important use for high accuracy is in targeting weapons by GPS, what the US Air Force is doing in Iraq this very day...

For a nuclear weapon, you don't really need a CEP of 50 metres or better unless you are trying to hit a missile silo. Even for a few hundred Kg of HE, a CEP of 10 metres or better is fine.

Re:Most Important Use for High Accuracy

[oldCoder]

GPS is more than one needs for nuclear weapons targeting, but is very convenient. The electronics are available anywhere, and the techniques for connecting it to an autopilot are readily available. If you're on a budget, you can test it out near home, reprogram it, bring your airplane in range, and just let it go.

If GPS is used this way, it will certainly be the most important use of GPS. The hard part, of course, is building the bomb. But that's getting easier. And if North Korea has its way, there will be a free market in nuclear warheads.

Re:Most Important Use for High Accuracy

[hughk]

The interesting thing is that the cost of a GPS system is immense, but with mass production of the receiver chips, the marginal cost is minute. In fact, it is probably cheaper to build the bomb than to launch a GPS constellation.

Somehow, I don't think there would be such a free market in nuclear weapons because an attack on America with a North Korean bomb, would probably bring retribution on the producer, not just the user.

Re:I agree with many Salon responses to rx spectru

[MrTilney]

Because the channels are very different. The physical network that the internet is routed over has the similiar problems, this is why wired data rates are limited. The data only network of the internet represents an ideal channel, although it is rate limited. In the real world, try as you might, the laws of electromagnetics keep getting in your way.

Re:Looks like it's only usable in Europe for now .

[OS2_will_prevail!]

You've never been sailing, have you? In the fog ... Try it some time - you might suddenly get to appreciate the advantages of accuracy

Tell me something...why do you think that the Coast Gaurd provides a free differential beacon? Could it be because you need something to make GPS more accurate than it is with Selective Availability? No...that could not be it. If you are sailing around, relying on nothing but a GPS reciever without differential correction to figure out where you are and where you are going, then you deserve to run aground.

Or you could try flying - in poor viz

Next time you are in your airplane flying around in poor visibility, you might notice that there are numerous round gauges and dials there in front of you in the cockpit. Theses are called instruments, and by reading them correctly, you will be able to figure out where you are going. In visibilty that is so poor that you cannot look out and see the world around you, you will be operating under instrument flight rules, or IFR. Hope you are certified for IFR flight. It is interesting to note that IFR has existed much longer than GPS, and in fact a GPS reciever is not one of the instruments that your craft must posess in order to operate under IFR.

My whole point is that people that need accuracy have it now, and will continue to have it. Its just not free.

But I agree, you just don't get it

Perhaps not, but in this regard, we are equals.

Re:Looks like it's only usable in Europe for now .

[SimonInOz]

Tell me something...why do you think that the Coast Gaurd provides a free differential beacon?

Er - they don't - I'm in Australia. The diferential service is pretty limited. Lots of coast, not many people.

People got to places before GPS. Even before sextants. And compasses. And charts. But they died a lot doing it.

I like GPS - its universal availablity and accuracy is a boon to all. Better accuracy would be good.

I obviously fit into the group you don't believe in, the ones who would like better accuracy and don't currently have access to it. But I'd have thought that was me and all the other non-wealthy offshore sailors in the world. Why should accuracy be restricted to the rich, as you appear to suggest, when a system available to all can offer it?

I reckon something else is going on here. Could it be you can't stand the idea of those dashed Europeans (especially France) having a more accurate system than the good old USA?

Re: "there's no real justification for Galileo."

[Anonymous Coward]

Well, I would say with the U.S. governments being increasingly warlike and anti "rest of the world", there must be.

It demonstrated it with anyone who has opposed the current Administration. Theres no guarantee a U.S. administration will be allies, never mind friends with the rest of the world. How can the rest of the world rely on their technology?

Trusting the GW Bush administration

[Nicolas MONNET]

You know what, trusting the Bush administration after the hilarious episodes of:

- Fake uranium orders from Niger
- Student's thesis from 12 years ago presented as convincing evidence
- Meaningless wiretappings presented as evidence ... conjures up images of the Goatse guy asking for more, much more up the ass.

Arg! The argument is the point!

[Erris]

Mesh routing schemes break down in highly populated areas - you end up with too many messages needing to be routed by any given node, and the fraction of node bandwidth used for that node's messages dropping like a rock.

That's debatable but think about what you are saying. If only a fraction of the currently restricted bandwith were so well utilized! As it is, you hear silence. Which is preferable? The possibility of a clog or enforced silence and frustration? What is it that you stand for?

Re:Looks like it's only usable in Europe for now .

[DJPenguin]

Surely if you have the GPS coordinates then you don't need the clues? Or do they just get you within a few hundred meters of the cache and you have to work out the rest for yourself?

James

Re:Looks like it's only usable in Europe for now .

[mmol_6453]

The caches are usually hidden. Also, sometimes the person who placed the cache couldn't get very good signal, and even if he could, he may not have been able to put the GPS in the exact position of the cache.

Even if the coordinates are exact, there's still the z factor.

Re:Looks like it's only usable in Europe for now .

[ByTor-2112]

That's for very expensive units that do postprocessing of the (I believe) pseudorange data that most handhelds don't output, as well as other corrections. Some require a link to another station to apply corrections. This is only found in survey-grade consumer GPS equipment.

Re:Looks like it's only usable in Europe for now .

[DancingSword]

I hear they needed some accuracy when digging the Channel Tunnel, like for putting cables in place, and mapping their precise position ( so as to not be drilling, or whatever, through 'em years later )...

Re:I agree with many Salon responses to rx spectru

[Anonymous Coward]

One point that all the respondants to the article seem to miss is that today's radio receivers effectively monitor only a single "point" in space. If you could use multiple antennae and look for phase differences then it would definitely be possible to resolve multiple transmitters on the same frequency -- something along the lines of a "phased array" receiver. The resulting device might be too bulky for the consumer market though.

The question is: do we really need this type of thing for the "broadcast" model of radio communication or can't we just use wireless networks for everything?

Re:FP

[unitron]

"*wipes coke off keyboard*"

Since Colombia was mentioned, which kind of coke?

Re:I agree with many Salon responses to rx spectru

[jafiwam]

Ah. Finally someone comes to the meat of the matter. Expect a submarine patent on the radio techonology that allows this new RF stuff to happen on such narrow bandwidths. You heard it here first.

Re:Looks like it's only usable in Europe for now .

[RevDobbs]

I am having trouble figuring out why anyone (outside of a small subset of the population) would need accuracy less than 50 feet or so.

Ask the people who were in an uproar when the found out that their Pentium 60's might have a floating-point division error that manifests itself in the fiftenth decimal place.

Bigger Better Stronger Faster and insanely Accurate. Isn't that everybody's goal?

Re:Looks like it's only usable in Europe for now .

[minektur]

Do you really think future tunnel digging enterprises will used satelite-based location devices - underground and perhaps even underwater, where the radio-waves are unlikley to penetrate?

Re:Looks like it's only usable in Europe for now .

[Lars T.]

More Information about EGNOS and WAAS.

You Dolt

[Anonymous Coward]

You give a link to a rumor that was started by the president of the German Auto club.

The US has not degraded nor have they threaten to degrade the signal.

You really really really are paranoid and dumb. The very things you accuse the US of being...you're ten times worse because you think you're smarter and you're the dumbest F'er on the planet.

The european system *is* all about vanity. Too bad you can't get past your own ideas and petty jealousy of the US.

Game over. You lose.

Re:You Dolt

[ergo98]

You give a link to a rumor that was started by the president of the German Auto club

Actually no I gave a link to a Slashdot discussion where people discuss the vulnerability of the world relying upon a system that the US administration controls.

The US has not degraded nor have they threaten to degrade the signal.

Actually when the US removed selective availability, they did so with the SPECIFIC DISCLAIMER that they retain the right to turn it back on whenever they felt like it. This is public policy my ignorant, backwards friend.

You really really really are paranoid and dumb. The very things you accuse the US of being...you're ten times worse because you think you're smarter and you're the dumbest F'er on the planet.

Ooooh, peirces like a knife!

The european system *is* all about vanity. Too bad you can't get past your own ideas and petty jealousy of the US.

You are exactly the sort of pissy "it's my ball!" sort of idiot that causes people to build their own system.

Re:Arg! The argument is the point!

[Christopher Thomas]

think about what you are saying. If only a fraction of the currently restricted bandwith were so well utilized! As it is, you hear silence. Which is preferable? The possibility of a clog or enforced silence and frustration?

Clogging is a certainty without imposed limits; people are greedy that way. Removing band restrictions just guarantees that *all* parts of the spectrum are clogged.

Band restriction is a quality of service issue - if you want to be able to use your cell phone, or to put up an antenna and hear music from your favourite radio station, there must be a guarantee that the person next door isn't cluttering up that section of the spectrum for you. This is especially true for emergency services, and for bands that interfere with important equipment (radio beacons at airports come to mind).

What is it that you stand for?

Wired backbones. All the bandwidth you can eat, and much less contention for it. Limit wireless to short range, and put hubs everywhere. Problem solved (for urban areas; rural areas are an entirely different problem with different constraints).

bad policy

[Erris]

you say: Limit wireless to short range, and put hubs everywhere. Problem solved (for urban areas; rural areas are an entirely different problem with different constraints).

So you would have no free long range high power spectrum at all? That's realy short sighted (pun intended), and I'm happy to think that the FCC chairman disagrees with you. The cost of all that badwith you want would be considerably less if more spectrum was given over to 802.11B type freedom. The equipment is cheap enough that people would build the infrastructure and run it as a free public service.

Re:bad policy

[Christopher Thomas]

Limit wireless to short range, and put hubs everywhere. Problem solved (for urban areas; rural areas are an entirely different problem with different constraints).

So you would have no free long range high power spectrum at all?

There would be a few bands open for hobbyists, just like there are now. Want to build a 1 kW transmitter? Go ahead - just get your ham license first. Decide you're not going to play nicely in the community? Your license gets revoked.

Without management, anything longer than short-range will cause too many people to step on each others' toes.

The cost of all that badwith you want would be considerably less if more spectrum was given over to 802.11B type freedom. The equipment is cheap enough that people would build the infrastructure and run it as a free public service.

The free public service would then start charging a modest fee to support its overhead, and then the core of people running it would slowly drift to the dark side as bureaucracy started fossilizing, and you'd end up with something indistinguishable from the bandwidth providers we currently have.

Do you think that Cthulhu came to earth and decided to found UUNet to torment the mortals? Large-scale utility providers _naturally_ evolve to become this way!

If you want cheaper bandwidth, start a letter-writing campaign to get better government regulation of the industry. It's a utility, just like phone and power and water and so forth. Manage it like one.

Re:Looks like it's only usable in Europe for now .

[DancingSword]

They needed to know precisely where they were GOING TO PUT THE THING, down to the 3cm, IIRC, because they needed to know the materials required, where the international rights/responsibilities changed, what kind of chalky-grey-stuff they were going to be tunnelling through ( use GPS, test sea-floor, move a bit, use GPS, test sea-floor, using triangulation of low-freq, which does penetrate water, or physical connection-to-bottom-of-sea, or whatever ), but they /did/ need precise measurements for the engineering.

Sorry if I fucked-up the rendition of it..

( engineers/architects usually get to go by surveyor's maps for city-stuff, right? well the chunnel was put where there weren't any surveyors-maps, so they had to create 'em, and there aren't alot of little bronze surveyor's spikes embedded in usual European sand beaches )

as it was in the begining ...

[Erris]

There would be a few bands open for hobbyists, just like there are now. Want to build a 1 kW transmitter? Go ahead - just get your ham license first. Decide you're not going to play nicely in the community? Your license gets revoked. Without management, anything longer than short-range will cause too many people to step on each others' toes.

Nonsense! No electronic device, licensed or unlicensed my interfere with federally allocated spectrum. You don't need to yank a license to shut someone down any more than I need to build my own kW system (the orignial 802.11 alocation was supposed to be 100W!). If it were legal to use the spectrum, reputable builders would come to the rescue. But the most important thing you miss is that the spectrum WILL BE USED where TODAY IT CAN'T BE!

The free public service would then start charging a modest fee to support its overhead, and then the core of people running it would slowly drift to the dark side as bureaucracy started fossilizing, and you'd end up with something indistinguishable from the bandwidth providers we currently have.

That's about as silly a notion as they come. "Because things are bad they always will be and we should not change."

Re:as it was in the begining ...

[Christopher Thomas]

No electronic device, licensed or unlicensed my interfere with federally allocated spectrum. You don't need to yank a license to shut someone down any more than I need to build my own kW system (the orignial 802.11 alocation was supposed to be 100W!). If it were legal to use the spectrum, reputable builders would come to the rescue.

You miss my point. I'll state it more clearly:

If you have a reason to transmit signals long distances, you can do so cheaply by filling out the appropriate forms and following the rules.

Reputable builders already exist - check out the ham community and the suppliers they buy from. If you want to *use* a 1 kW transmitter, you'd better have a license for it.

But the most important thing you miss is that the spectrum WILL BE USED where TODAY IT CAN'T BE!

And this is a problem why?

If you're running short-range to wired hubs, there is no shortage of data capacity in the bands already alotted.

If you for some reason want to operate a higher-power transmitter and use it to flood large parts of the spectrum with your data... then I'm glad you don't have a transmitter. You and everyone else in your neighbourhood would be stepping on each others' toes. You have nicely proved my point.

That's about as silly a notion as they come. "Because things are bad they always will be and we should not change."

If you believe that there is a magical way to run a wired backbone at half the cost to the user, sell the business plan to the highest bidder. Last I checked the backbone providers were pretty deep in the red.

Re:Looks like it's only usable in Europe for now .

[minektur]

Your more verbose explanation makes quite a bit more sense. Thanks.