Spoken like someone who doesn't own one or know much about them.
The Zaurus does compete with a notebook, more than any other "pocket pc" out there.
I may or may not be able to do the ONE SPECFIC THING that you want it to do, but that doesn't qualify you to call it a miserable failure.
That's like calling planes a miserable failure because we all drive cars. They're useful, but like everything else out there, they have strengths and weaknesses.
If you have a few small PDA-size computers which all have the software, redundancy can save you from this problem.
Great! So instead of carrying around one small, light, flexible map the soldier gets to carry around THREE brick sized PDAs.
That's not a solution in my book.
I suggest PocketPCs (or similar) with biometric identification
I would REALLY strongly suggest against that. Think about it: I shoot a soldier from behind, run up, grab his PDA, and use his fingerprint to log right in.
Biometrics are so frickin overrated it's sick. If you're gonna do something like that, use a PASSWORD so it dies when the user dies.
which are self-scrambling (or -destroying) if left unattended for a sufficiently long time.
Also a bad idea. A soldier has better things to think about than whether his PDA is going to self-destruct because he hasn't logging in recently enough.
A much better way would be to make it automatically log out after a short period of inactivity. (When logged out, all files would be in an encrypted format.)
No need to strand some poor soldier without a map because he forgot his PDA when he was taking a leak a mile back.
I'm not totally against the idea of electronic maps for soldiers, but I think one needs to consider the real-world implications of such a thing.
doesn't have VGA out nor DVI, so how exactly is
this useful again? Does it at least have a couple
of USB slots?
Does it take QIC-80 tapes and zip discs?
No, well then it's useless.
I mean, fuck, you're always going to be able find SOMETHING a device can't do and then say "it's useless".
(Of course you haven't done your homework either, since last I knew a VGA output card for the CF slot was already availible in japan and perhaps on the way to the US.)
If Diebold machines get in the 2004 primary election, we're all screwed if we're not voting for Bush. Think about it.
If by some chance, Kerry wins the election...and the media going apeshit because Bush has been dethroned
I think this is a good time to remind everyone that Bush's dad used to be head of the CIA.
I would be much more afraid that Bush wins (despite the "mission" being "accomplished"), with the help of some help from the same type of folks who brought us Iran-contra.
I would definately not put it past a memeber of the Bush family to break the law for politcal gain, so long as they think they won't get caught.
A machine that gives you a paper receipt of your vote isn't worth a damn if someone can hack the smartcard that records the votes to log something else after the certification is complete.
WTF are you talking about?!
You completely miss the point here:
The paper is supposed to STAY AT THE POLLS
The paper provides a way to DOUBLECHECK THE ELECTRONIC RECORD.
Paper-trail e-voting is THE solution. It's fuckin HARD to tamper with a piece of paper inside a locked metal box that is only opened in front of multiple witnesses. Bits can be silently and instantly manipulated, but paper's harder to fudge.
Given that this type of standardized interface exists, and that tools for "exploiting" it are readily available and fairly cheap, I don't see how it would be possible to keep this information (error codes and the like) secret.
You are misinformed.
ODBII is only a pathetic subset of what it should be.
"remapping" the engine is done via the ODBII port, but it's completely manufacturer-specfic and proprietary.
Other proprietary things include, ABS, climate controls, etc. All of that stuff you need a special manufacturer-specfic computer for.
You might be lucky and own a car where a 3rd party, reverse-engineered solution exsists, but many people aren't, and it's quite possible to keep things secret.
Seriously, all you need to do is use crypto, and keep the key on the same silicon as the processor, and presto, "you're fucked". At least unless you're a grad student at a university with a nanotech facility.
Personally, I'm in the process of reverse engineering the ECU for my '86 Mazda RX-7. Luckily, in those days, RAM, ROM, and CPU were all seperate chips. If the ECU in my car was using a modern processor with some built-in storage and code-protection features, there wouldn't be crap I could do.
In a few years, it's quite possible cracking the code on an ECU could become as difficult as cracking a smartcard. It's already difficult enough that for certain new cars like the RX-8, tuners are going with additional "piggyback" computers, rather than attempting to work with what's there. Mazda has the capability to re-flash the ECU, but you don't, and you many never depending on what security features they've chosen to include. IIRC BMW has just changed the proprietary codes on some of their cars as well.....
Hence, the diagnostic system in the car is unlikely to be "protected" by an access "protection" device any time in this decade, but after that all bets are off.
Actually, they are right now.
If you drive into the dealership with you 2004 whatever, chances are they can load new fuel/timng maps into you ECU quite easily, via the ODBII port.
Why can't I do this?
Two reasons....
1) The specs aren't published to do it.
2) The you need some sort of "password".
#2 is the key here. For certain car's the password/"security seed" has been reverse enginneered (like Corvette's.... google on "LS1edit") but for many cars you're just screwed.
OBDII pisses me off because it's a pathetic subset of what you SHOULD have, and manufacturers know this. The is just no way, to, for example, bleed the ABS, via "open standard" ODBII commands.
To me, that's bullshit. When you're talking about things like ABS not working properly it's becomes a significant safety issue.
Then I come along and decide that I don't like you all, for whatever reason. So I build a transmitter that operates on the WiFi band, but spews noise with 2000 watts of power through a massive antenna. Suddenly your WiFi is worthless. However there's nothing you can do, since there's no regulation. What I'm doing is legal, though assinie.
Obviously we need regulation, it's just that the current regulation is just plain stupid.
It made sense back when everything was either AM or FM, but now the we have things like CDMA, TDMA, etc. the whole "one person per channel" concept is just stupid".
Look at the GPS system. You can buy a device that will receive from 12 different satellites on the same frequency ALL BROADCASTING SIMULTANEOUSLY.
We have to share the airwaves just like we have to share roads.
Except right now what we're doing is just having a seperate lane for fire, a seperate lane for ambulance, a seperate lane for trucks, a seperate lane for taxis, etc. It made sense back when rados weren't smart enough to "share", but that just isn't the case anymore.
The point is that the current FCC rules are outdated and wasteful, not that we shouldn't have regulation at all.
even if the hose was metal, it is long and has a significant inductance.
Know what else is long and has inductance?
A car.
Your assumption sabout free space impedance are also utter junk, the thing that matters is the apparent impedance at the end of the bit of metal, which can go a lot higher.
What matters is the power involved. With 1 watt of power, there's a limit to the electrical field you're gong to generate at the antenna, and everything goes downhill exteremely rapidly from there. Even if you had a PERFECT antenna one meter away from a cellphone, you're not going to be able to blow yourself up.
Try this simple experiment:
Take a cellphone.
Unscrew the antenna.
Hold it close to a grounded metal plate.
Place a call on another cellphone.
Watch in awe as no sparks appear.
Realize you're full of crap.
When people like you resort to bad language, it is because they either have no coherent argument, have lost the argument, or are just plain incompetent.
It was you as an expletive, to express shock and awe at the crap I was reading.
Any proper electrical engineer would be aware of capacitance and inductance, resonance and transmission line effects.
Guess what else "proper engineers" deal with? The real world.
An antenna is a transmission line terminated with an open circuit.
Actually, an antenna should be viewed as an impedance matching device to free space.
The voltage at the end is quite high.
Say cellphones had a whole watt of tranmitter power. Zo = 377 ohms, the impedance of free space. P=V^2/R, so V=19.4 volts RMS. That's 19.4 volts AT THE DAMNED TRANSMITTER!
"Repeat after me: 3 volts do not arc."
Sure it does, under a number of conditions.
None of these conditions are present in a cellphone.
But when breaking a circuit with current flowing through it you end up with exactly that microscopic gap initially. Once the air is ionized the arc can be sustained by a very low voltage. And with any inductance in the circuit at all (even the stray inductance from the wiring) the voltage will climb to maintain the arc until the current through the inductor is finally brought to a halt by the reverse voltage.
Nonsense. Utter nonsense. You're getting all sorts of concepts confused.
If there was a significant inductance, THE "CIRCUIT" WOULD NOT BE RESONATING AT RF FREQUENCIES.
So the arc can be "pulled out" to significant lengths.
This phenomena is caused by air's reduced resistance once you've started the arc.
This is EXACTLY the mechanism that produces the voltage spike in the primary (and thus also in the secondary) of the transformer in a contact-point type auto ignition.
No, it's not. An ignition coil is supplied with a continuous DC (NOT RF!) current flow.
The spark happens when an antenna, typically the pump nozzle, receives RF energy and converts it into voltage and current, which then may cause a spark between the antenna and another bit of metal, also technically an antenna but it will function more like ground in this instance, the vehicle body.
Bullshit. Why are you posting this drivel?
Do you have ANY idea what the power levels used by cellphones are?
To give an example of just one of the many ways this post is full of shit:
The NOZZLE would function as the ground because it's grounded through the gas pump. The CAR is what's insulated from the ground by its RUBBER TIRES.
This guy is 100% full of crap. Mods, I know I'm ranting here, but as an electrical engineer, the shit I'm seeing in this thread makes my stomach turn.
People like this make those of us who actually DO know something about electricity look bad.
I'm just flat out floored by the number of these bullshit "RF causing sparks" posts. The amount of people who don't know what the fuck they're talking about yet are willing to run their mouths is truely amazing.
Ok, I'm going to debunk this two ways: technically and non-technically.
First, the technical. Say cellphones had a whole watt of tranmitter power. Zo = 377 ohms, the impedance of free space. P=V^2/R, so V=19.4 volts RMS. That's right folks 19.4 volts AT THE DAMNED TRANSMITTER!
Now the non-technical. If cellphones are so dangerous why the fuck haven't police cruisers, with their myriad of higher-power systems been exploding at pumps?
You quoted: Education has the highest correlation coefficient to lack of belief in a personal god. By most surveys, more than 90% of professional scientists don't believe in a personal god.
And said:
I can buy the second statement, but not necessarily the first. There are plenty of people with higher education who are not scientists.
This made me laugh out loud. Of course there are plently of educated people who aren't scientists, that does not dispute anything in that second sentence.
It's like me saying., most people with doctorates make a pretty good living. 90% lawyers make in the neighborhood of 100K/year.
Well, of course not EVERYONE with a doctorate is a lawyer, but saying that does nothing but show that you missed the point.
Religion is about suppressing your own ego and having compassion for those around you, which is something that a lot of scientists could sorely use.
Suppressing your own ego how? By believing that have found the one true religion? By claiming to "know" things about god based on unverifiable, anedotal evidence, that was meant to be allegorical?
Compare that to a scientist who submits his ideas to things like peer review and independent verification by impartial third parties who is expected to hold himself to a high standard of credibility.
In fact my opinion is that the existence of God is an axiom. This fits because axioms are initial assumptions that cannot be tested, and as yet nobody has even developed a convincing test for the existence of God.
Arguments like this are funny. I can say:
"I have an undetectable Nerf Ball that floats above my head and follows me everywhere I go."
Guess what?
You can't prove me wrong!
Why not?
Because the statement is specfically formulated to be that way. It's not a REAL axiom, it's more of a play with words and semantics.
See, what a Nerf Ball is, is already defined. If it's "undetectable", then it's not a Nerf Ball any more than George Bush is. Realistically, "undetectable Nerf Ball"=NOTHING. This means my statement can be restated as:
"I have nothing that floats above my head and follows me...."
There reason your "axiom" is not getting disproved is because the contruction is logically flawed to begin with.
As for the "90% of scientists" claim, I think that's a nasty prejudice on the part of scientists, rather than something to be proud of.
Actually, this shows a "nasty prejudice" on your part. Did you every stop to think that these scientists might have made logical, reasoned conclusions, rather than snap judgements, and maybe the reason most of them don't believe is because it does not make sense? That and perhaps they have even the slightest grasp on the history and psychology of man.
Calvin: What makes the wind?
Dad: Trees sneezing.
Calvin: Really?
Dad: No, but the real answer is much more complex.
If you want to spend the rest of your life arguing the intracacies of "trees sneezing", and making progressivly ridiculous exceptions in order to keep your theory from being disproven, I can't stop you, but don't be suprised when scientists don't take your "axiom" very seriously.
How could this be modded insightful? What kind of sheep are populating slashdot these days? You could learn enough about encryption to know that this is nonsense just by reading slashdot comments on past RFID articles, let alone actually having any common sense.
Yeesh. What an arrogant asshole you are. The post I was replying to made no mention of crypto. Of course RFID tags *could* emply public/private key crypto, but the reality is that most of the don't and won't.
RFID tags with actual crypto processors are significantly more expensive, harder to find, and there's no mention of their use in this article.
What you're assuming is like assuming that cars given away in radio station contests all have bullet-proof glass. Sure bullet-proof glass is availible, but it's stupid to just assume it's there.
If only you understood the first thing about encryption. The key is never transmitted.
Look up public/private key systems.
It is NOT a good idea to make the assumption that encryption is involved here. Most RFID tech (read: what Walmart's calling for) is NOT going to involve encryption.
Do you actually think this bar paid the extra money for the *expensive* RFID tags with actual processors in them? I may have a bridge to sell you......
RFID tags come with a random 128-bit number burnt into them at the factory. Sorry.
You don't get it.
All you would need is a simple RF recording and playback device.
When you walk up to the bar, I hit "record". When you pay, I've got your 128 bit number.
Then I walk up the bar and hit "play". Congratulations, your "unique" 128 bit number has just paid for my drink.
It would be similar to the "codegrabbing" devices that have been used to bypass car alarms and garage doors.
If one was particularly clever, they could build the device as an attachment to a device like an ipaq or an ipod, allowing it to be used inconspicuously.
Yeah, because I know *I* have the resources to defend myself in court because my programs have an interface that is similar to some corporation's software?
That's a damned good idea.
Well, that's something else that obviously needs to change. Right now civil ligitgation is like a no-limit poker game, where once you run out of money for lawyers, you loose by default.
I think that's something else that definately needs to change, but I still feel that the concept of an organization that can understand the nuances of every type of technology in the world is an outdated concept. There's just too much out there now.
It would be like the copyright office trying to verify that your "new" song isn't a ripoff on any other song that has come before.
I hate to burst your rant bubble, but that's always how it has worked. The USPTO is not in the business of saying a patent is "valid" or not.
They don't have the last say, but they're currently supposed to do supposed to check out applications, and often reccommend changes. It's definately not a "shall issue" short of thing where I hand you a document and I automatically get a patent.
What become clear to me over the last few years is that the US Patent Office has descended to little more than a registry system, like copyright registration. All a patent really says these days is "I had this idea on this date."
Personally, I think the USPTO should stop claiming to even attempt to research patents. They should just take your submission, slap a date on it, and stick in their files. The USPTO clearly does not have the resources/desire/ability to verify that everything that crosses their desks are actually vaid patents, so we should quit assuming that they are and let the court system sort it out when necessary.
I'd like to see auto makers combine the output from different energy sources into all-wheel acceleration of a normal car. I remember seeing something on the news a few years ago about Ford experimenting with that on an Explorer, trying to jazz up the acceleration of a bigger vehicle.
Most murder has nothing to do with making a profit for the murderer.
Perhaps maybe that's because where you live there are laws in place against murder?
The point is, if you've got something I want, there is ALWAYS going to be an incentive for me to kill you an take it. The idea is to create an ADDITIONAL disincentive. Just as you cannot remove the incentive for me to kill you and take your stuff, you cannot remove the financial incentive for spam. It's just not gonna happen.
The citizens of the United States really need to get over this "Land of the Free" bullshit and realise that their government is just as tyranical, expansionistic and controlling as any other.
Oh come on. Get real buddy.
Sure the US has its problems, but saying we're just as bad as anyone else is just plain stupid.
It really is just mindblowingly stupid. We have written laws, elected representatives, checks and balances, etc, etc. If you think this you no better than some dictator with a gun running aroud doing whatever he wants you're a moron.
Sure, I'm upset about the patriot act, "enemy combatant" status, etc, but I'm still glad to not live in a country where a bunch of AK-47 wielding "Judge Dredd" motherfuckers go around wasting anyone they want.
You missed his point.
First off, supersonic is FAST. From a HUMAN viewpoint a supersonic bullet is so fast that it could fly right by your nose and you wouldn't even see it. Just because there are faster things out there, doesn't mean it's not fast by any reasonable definition of the world.
And his point is that RIGHT NOW there isn't a radar out there that will pick up a bullet in the air.
Lots of problems sure, but not totally impossible to consider in the not so distant future.
Acutally, there's about one metric assload of problems. Besides getting the wavelength small enough, you would also need to be able to complete the search for and tracking of the bullet in a TINY amount of time because you need time left over to do something about it. You can't just say "You have 100ms to respond" because your radar has to find the bullet in the air first. THEN, once you know there's a bullet in the air, you need to determine its trajectory well enough that you know where it's going to be within 1mm. Once, you've done that you have however much is left over to actually do something about the bullet.
Let's think about this here:
Say you could actually build a radar with a beam width of 1mm, and you want to detect the bullet 100m away:
2*arctan(.001/100)=2E-5 rad say you want to check a 90 deg by 90 deg area... ((pi/2) * (pi/2)) / 2E-5 = 123370 beam positions but wait....how long does light take to travel 100m ? 100m / 3E9 m/s = 3.3E-8 seconds multiply this by the number of beam positions: =.004112 seconds and of course this gives the pulse that hit the bullet no WIDTH and they'd therefore be undetectable (no power to detect), so you need to multiply in a pulse width as well. The wavelength we're using is 1mm, so the frequency is v=f * lambda 3e9 m/s= f *.001m f=3e12 Hz so period is T = 1/f = 3.33E-13 s say we use five periods 3.33E-13*5*123370=2.056E-7 seconds to get some power on the target (Hey, this # doesn't look so bad:)
So we're already up to about 4 ms to get a SINGLE return from the target, but you're going to need multiple returns in order to decide there's acutally a bullet there. Say you require 3 returns from the bullet, that'd be 12ms. This would be the time it takes before you even BEGIN to point your laser in the right direction. Then your radar goes into a tracking mode, trying to get a good enough position on the bullet, while laser itself is trying to get pointed in the right direction.
Essentially, I'm trying to say that a radar-guided laser that shoots down bullets isn't something that's just a few years of, it's something that sits near the fundamental limits of what can be done. Even during that "long" 100ms you're talking about, using a radar that we can't build right now, 12% of it is gone before you even know a bullet is in the air. From that point, you need to hit the bullet enough times with your radar to be able to aim your laser at it, and THEN you'd need to "zap" the bullet with your laser long enough to do something about it.
And meanwhile it's not that hard to make the bullet go twice as fast, or to fire five bullets at once. (Combine those two and you're fucked.)
Slashdot Mirror
Zaurus comes close but still fails miserably.
Spoken like someone who doesn't own one or know much about them.
The Zaurus does compete with a notebook, more than any other "pocket pc" out there.
I may or may not be able to do the ONE SPECFIC THING that you want it to do, but that doesn't qualify you to call it a miserable failure.
That's like calling planes a miserable failure because we all drive cars. They're useful, but like everything else out there, they have strengths and weaknesses.
If you have a few small PDA-size computers which all have the software, redundancy can save you from this problem.
Great! So instead of carrying around one small, light, flexible map the soldier gets to carry around THREE brick sized PDAs.
That's not a solution in my book.
I suggest PocketPCs (or similar) with biometric identification
I would REALLY strongly suggest against that. Think about it: I shoot a soldier from behind, run up, grab his PDA, and use his fingerprint to log right in.
Biometrics are so frickin overrated it's sick. If you're gonna do something like that, use a PASSWORD so it dies when the user dies.
which are self-scrambling (or -destroying) if left unattended for a sufficiently long time.
Also a bad idea. A soldier has better things to think about than whether his PDA is going to self-destruct because he hasn't logging in recently enough.
A much better way would be to make it automatically log out after a short period of inactivity. (When logged out, all files would be in an encrypted format.)
No need to strand some poor soldier without a map because he forgot his PDA when he was taking a leak a mile back.
I'm not totally against the idea of electronic maps for soldiers, but I think one needs to consider the real-world implications of such a thing.
doesn't have VGA out nor DVI, so how exactly is this useful again? Does it at least have a couple of USB slots?
Does it take QIC-80 tapes and zip discs?
No, well then it's useless.
I mean, fuck, you're always going to be able find SOMETHING a device can't do and then say "it's useless".
(Of course you haven't done your homework either, since last I knew a VGA output card for the CF slot was already availible in japan and perhaps on the way to the US.)
"A computer with a bullet in it is just a paperweight. A map with a bullet in it is still a map."
-Maj. Keith Hauk
.if you're gonna base all your corporate strategy on lawsuits, you better get your sh*t together and at least make the court deadlines on time.
:)
It's awfully hard to produce things that don't exist by ANY dealine
If Diebold machines get in the 2004 primary election, we're all screwed if we're not voting for Bush. Think about it. If by some chance, Kerry wins the election...and the media going apeshit because Bush has been dethroned
I think this is a good time to remind everyone that Bush's dad used to be head of the CIA.
I would be much more afraid that Bush wins (despite the "mission" being "accomplished"), with the help of some help from the same type of folks who brought us Iran-contra.
I would definately not put it past a memeber of the Bush family to break the law for politcal gain, so long as they think they won't get caught.
WTF are you talking about?!
You completely miss the point here:
- The paper is supposed to STAY AT THE POLLS
- The paper provides a way to DOUBLECHECK THE ELECTRONIC RECORD.
Paper-trail e-voting is THE solution. It's fuckin HARD to tamper with a piece of paper inside a locked metal box that is only opened in front of multiple witnesses. Bits can be silently and instantly manipulated, but paper's harder to fudge.Given that this type of standardized interface exists, and that tools for "exploiting" it are readily available and fairly cheap, I don't see how it would be possible to keep this information (error codes and the like) secret.
You are misinformed.
ODBII is only a pathetic subset of what it should be.
"remapping" the engine is done via the ODBII port, but it's completely manufacturer-specfic and proprietary.
Other proprietary things include, ABS, climate controls, etc. All of that stuff you need a special manufacturer-specfic computer for.
You might be lucky and own a car where a 3rd party, reverse-engineered solution exsists, but many people aren't, and it's quite possible to keep things secret.
Seriously, all you need to do is use crypto, and keep the key on the same silicon as the processor, and presto, "you're fucked". At least unless you're a grad student at a university with a nanotech facility.
Personally, I'm in the process of reverse engineering the ECU for my '86 Mazda RX-7. Luckily, in those days, RAM, ROM, and CPU were all seperate chips. If the ECU in my car was using a modern processor with some built-in storage and code-protection features, there wouldn't be crap I could do.
In a few years, it's quite possible cracking the code on an ECU could become as difficult as cracking a smartcard. It's already difficult enough that for certain new cars like the RX-8, tuners are going with additional "piggyback" computers, rather than attempting to work with what's there. Mazda has the capability to re-flash the ECU, but you don't, and you many never depending on what security features they've chosen to include. IIRC BMW has just changed the proprietary codes on some of their cars as well.....
Hence, the diagnostic system in the car is unlikely to be "protected" by an access "protection" device any time in this decade, but after that all bets are off.
Actually, they are right now.
If you drive into the dealership with you 2004 whatever, chances are they can load new fuel/timng maps into you ECU quite easily, via the ODBII port.
Why can't I do this?
Two reasons....
1) The specs aren't published to do it.
2) The you need some sort of "password".
#2 is the key here. For certain car's the password/"security seed" has been reverse enginneered (like Corvette's.... google on "LS1edit") but for many cars you're just screwed.
OBDII pisses me off because it's a pathetic subset of what you SHOULD have, and manufacturers know this. The is just no way, to, for example, bleed the ABS, via "open standard" ODBII commands.
To me, that's bullshit. When you're talking about things like ABS not working properly it's becomes a significant safety issue.
Then I come along and decide that I don't like you all, for whatever reason. So I build a transmitter that operates on the WiFi band, but spews noise with 2000 watts of power through a massive antenna. Suddenly your WiFi is worthless. However there's nothing you can do, since there's no regulation. What I'm doing is legal, though assinie.
Obviously we need regulation, it's just that the current regulation is just plain stupid.
It made sense back when everything was either AM or FM, but now the we have things like CDMA, TDMA, etc. the whole "one person per channel" concept is just stupid".
Look at the GPS system. You can buy a device that will receive from 12 different satellites on the same frequency ALL BROADCASTING SIMULTANEOUSLY.
We have to share the airwaves just like we have to share roads.
Except right now what we're doing is just having a seperate lane for fire, a seperate lane for ambulance, a seperate lane for trucks, a seperate lane for taxis, etc. It made sense back when rados weren't smart enough to "share", but that just isn't the case anymore.
The point is that the current FCC rules are outdated and wasteful, not that we shouldn't have regulation at all.
How could it happen? The timeline is all wrong. It would have to be like, Kirk's granfather or something.
They'd probably just pull the same crap they did when the wanted to have scotty show up.
rubber AND metal.
even if the hose was metal, it is long and has a significant inductance.
Know what else is long and has inductance?
A car.
Your assumption sabout free space impedance are also utter junk, the thing that matters is the apparent impedance at the end of the bit of metal, which can go a lot higher.
What matters is the power involved. With 1 watt of power, there's a limit to the electrical field you're gong to generate at the antenna, and everything goes downhill exteremely rapidly from there. Even if you had a PERFECT antenna one meter away from a cellphone, you're not going to be able to blow yourself up.
Try this simple experiment:
When people like you resort to bad language, it is because they either have no coherent argument, have lost the argument, or are just plain incompetent.
It was you as an expletive, to express shock and awe at the crap I was reading.
Any proper electrical engineer would be aware of capacitance and inductance, resonance and transmission line effects.
Guess what else "proper engineers" deal with?
The real world.
An antenna is a transmission line terminated with an open circuit.
Actually, an antenna should be viewed as an impedance matching device to free space.
The voltage at the end is quite high.
Say cellphones had a whole watt of tranmitter power. Zo = 377 ohms, the impedance of free space. P=V^2/R, so V=19.4 volts RMS. That's 19.4 volts AT THE DAMNED TRANSMITTER!
"Repeat after me: 3 volts do not arc."
Sure it does, under a number of conditions.
None of these conditions are present in a cellphone.
But when breaking a circuit with current flowing through it you end up with exactly that microscopic gap initially. Once the air is ionized the arc can be sustained by a very low voltage. And with any inductance in the circuit at all (even the stray inductance from the wiring) the voltage will climb to maintain the arc until the current through the inductor is finally brought to a halt by the reverse voltage.
Nonsense. Utter nonsense. You're getting all sorts of concepts confused.
If there was a significant inductance, THE "CIRCUIT" WOULD NOT BE RESONATING AT RF FREQUENCIES.
So the arc can be "pulled out" to significant lengths.
This phenomena is caused by air's reduced resistance once you've started the arc.
This is EXACTLY the mechanism that produces the voltage spike in the primary (and thus also in the secondary) of the transformer in a contact-point type auto ignition.
No, it's not. An ignition coil is supplied with a continuous DC (NOT RF!) current flow.
The spark happens when an antenna, typically the pump nozzle, receives RF energy and converts it into voltage and current, which then may cause a spark between the antenna and another bit of metal, also technically an antenna but it will function more like ground in this instance, the vehicle body.
Bullshit. Why are you posting this drivel?
Do you have ANY idea what the power levels used by cellphones are?
To give an example of just one of the many ways this post is full of shit:
The NOZZLE would function as the ground because it's grounded through the gas pump. The CAR is what's insulated from the ground by its RUBBER TIRES.
This guy is 100% full of crap. Mods, I know I'm ranting here, but as an electrical engineer, the shit I'm seeing in this thread makes my stomach turn.
People like this make those of us who actually DO know something about electricity look bad.
I'm just flat out floored by the number of these bullshit "RF causing sparks" posts. The amount of people who don't know what the fuck they're talking about yet are willing to run their mouths is truely amazing.
Ok, I'm going to debunk this two ways: technically and non-technically.
First, the technical. Say cellphones had a whole watt of tranmitter power. Zo = 377 ohms, the impedance of free space. P=V^2/R, so V=19.4 volts RMS. That's right folks 19.4 volts AT THE DAMNED TRANSMITTER!
Now the non-technical. If cellphones are so dangerous why the fuck haven't police cruisers, with their myriad of higher-power systems been exploding at pumps?
You quoted:
Education has the highest correlation coefficient to lack of belief in a personal god. By most surveys, more than 90% of professional scientists don't believe in a personal god.
And said:
I can buy the second statement, but not necessarily the first. There are plenty of people with higher education who are not scientists.
This made me laugh out loud. Of course there are plently of educated people who aren't scientists, that does not dispute anything in that second sentence.
It's like me saying., most people with doctorates make a pretty good living. 90% lawyers make in the neighborhood of 100K/year.
Well, of course not EVERYONE with a doctorate is a lawyer, but saying that does nothing but show that you missed the point.
Religion is about suppressing your own ego and having compassion for those around you, which is something that a lot of scientists could sorely use.
Suppressing your own ego how? By believing that have found the one true religion? By claiming to "know" things about god based on unverifiable, anedotal evidence, that was meant to be allegorical?
Compare that to a scientist who submits his ideas to things like peer review and independent verification by impartial third parties who is expected to hold himself to a high standard of credibility.
In fact my opinion is that the existence of God is an axiom. This fits because axioms are initial assumptions that cannot be tested, and as yet nobody has even developed a convincing test for the existence of God.
Arguments like this are funny. I can say:
"I have an undetectable Nerf Ball that floats above my head and follows me everywhere I go."
Guess what?
You can't prove me wrong!
Why not?
Because the statement is specfically formulated to be that way. It's not a REAL axiom, it's more of a play with words and semantics.
See, what a Nerf Ball is, is already defined. If it's "undetectable", then it's not a Nerf Ball any more than George Bush is. Realistically, "undetectable Nerf Ball"=NOTHING. This means my statement can be restated as:
"I have nothing that floats above my head and follows me...."
There reason your "axiom" is not getting disproved is because the contruction is logically flawed to begin with.
As for the "90% of scientists" claim, I think that's a nasty prejudice on the part of scientists, rather than something to be proud of.
Actually, this shows a "nasty prejudice" on your part. Did you every stop to think that these scientists might have made logical, reasoned conclusions, rather than snap judgements, and maybe the reason most of them don't believe is because it does not make sense? That and perhaps they have even the slightest grasp on the history and psychology of man.
Calvin: What makes the wind?
Dad: Trees sneezing.
Calvin: Really?
Dad: No, but the real answer is much more complex.
If you want to spend the rest of your life arguing the intracacies of "trees sneezing", and making progressivly ridiculous exceptions in order to keep your theory from being disproven, I can't stop you, but don't be suprised when scientists don't take your "axiom" very seriously.
How could this be modded insightful? What kind of sheep are populating slashdot these days? You could learn enough about encryption to know that this is nonsense just by reading slashdot comments on past RFID articles, let alone actually having any common sense.
Yeesh. What an arrogant asshole you are. The post I was replying to made no mention of crypto. Of course RFID tags *could* emply public/private key crypto, but the reality is that most of the don't and won't.
RFID tags with actual crypto processors are significantly more expensive, harder to find, and there's no mention of their use in this article.
What you're assuming is like assuming that cars given away in radio station contests all have bullet-proof glass. Sure bullet-proof glass is availible, but it's stupid to just assume it's there.
If only you understood the first thing about encryption. The key is never transmitted.
Look up public/private key systems.
It is NOT a good idea to make the assumption that encryption is involved here. Most RFID tech (read: what Walmart's calling for) is NOT going to involve encryption.
Do you actually think this bar paid the extra money for the *expensive* RFID tags with actual processors in them? I may have a bridge to sell you......
RFID tags come with a random 128-bit number burnt into them at the factory. Sorry.
You don't get it.
All you would need is a simple RF recording and playback device.
When you walk up to the bar, I hit "record". When you pay, I've got your 128 bit number.
Then I walk up the bar and hit "play". Congratulations, your "unique" 128 bit number has just paid for my drink.
It would be similar to the "codegrabbing" devices that have been used to bypass car alarms and garage doors.
If one was particularly clever, they could build the device as an attachment to a device like an ipaq or an ipod, allowing it to be used inconspicuously.
Yeah, because I know *I* have the resources to defend myself in court because my programs have an interface that is similar to some corporation's software?
That's a damned good idea.
Well, that's something else that obviously needs to change. Right now civil ligitgation is like a no-limit poker game, where once you run out of money for lawyers, you loose by default.
I think that's something else that definately needs to change, but I still feel that the concept of an organization that can understand the nuances of every type of technology in the world is an outdated concept. There's just too much out there now.
It would be like the copyright office trying to verify that your "new" song isn't a ripoff on any other song that has come before.
I hate to burst your rant bubble, but that's always how it has worked. The USPTO is not in the business of saying a patent is "valid" or not.
They don't have the last say, but they're currently supposed to do supposed to check out applications, and often reccommend changes. It's definately not a "shall issue" short of thing where I hand you a document and I automatically get a patent.
What become clear to me over the last few years is that the US Patent Office has descended to little more than a registry system, like copyright registration. All a patent really says these days is "I had this idea on this date."
Personally, I think the USPTO should stop claiming to even attempt to research patents. They should just take your submission, slap a date on it, and stick in their files. The USPTO clearly does not have the resources/desire/ability to verify that everything that crosses their desks are actually vaid patents, so we should quit assuming that they are and let the court system sort it out when necessary.
I'd like to see auto makers combine the output from different energy sources into all-wheel acceleration of a normal car. I remember seeing something on the news a few years ago about Ford experimenting with that on an Explorer, trying to jazz up the acceleration of a bigger vehicle.
Here's a link you might like.
Most murder has nothing to do with making a profit for the murderer.
Perhaps maybe that's because where you live there are laws in place against murder?
The point is, if you've got something I want, there is ALWAYS going to be an incentive for me to kill you an take it. The idea is to create an ADDITIONAL disincentive.
Just as you cannot remove the incentive for me to kill you and take your stuff, you cannot remove the financial incentive for spam. It's just not gonna happen.
The citizens of the United States really need to get over this "Land of the Free" bullshit and realise that their government is just as tyranical, expansionistic and controlling as any other.
Oh come on. Get real buddy.
Sure the US has its problems, but saying we're just as bad as anyone else is just plain stupid.
It really is just mindblowingly stupid. We have written laws, elected representatives, checks and balances, etc, etc. If you think this you no better than some dictator with a gun running aroud doing whatever he wants you're a moron.
Sure, I'm upset about the patriot act, "enemy combatant" status, etc, but I'm still glad to not live in a country where a bunch of AK-47 wielding "Judge Dredd" motherfuckers go around wasting anyone they want.
You missed his point.
First off, supersonic is FAST. From a HUMAN viewpoint a supersonic bullet is so fast that it could fly right by your nose and you wouldn't even see it. Just because there are faster things out there, doesn't mean it's not fast by any reasonable definition of the world.
And his point is that RIGHT NOW there isn't a radar out there that will pick up a bullet in the air.
Lots of problems sure, but not totally impossible to consider in the not so distant future.
Acutally, there's about one metric assload of problems. Besides getting the wavelength small enough, you would also need to be able to complete the search for and tracking of the bullet in a TINY amount of time because you need time left over to do something about it. You can't just say "You have 100ms to respond" because your radar has to find the bullet in the air first. THEN, once you know there's a bullet in the air, you need to determine its trajectory well enough that you know where it's going to be within 1mm. Once, you've done that you have however much is left over to actually do something about the bullet.
Let's think about this here:
Say you could actually build a radar with a beam width of 1mm, and you want to detect the bullet 100m away:
Essentially, I'm trying to say that a radar-guided laser that shoots down bullets isn't something that's just a few years of, it's something that sits near the fundamental limits of what can be done. Even during that "long" 100ms you're talking about, using a radar that we can't build right now, 12% of it is gone before you even know a bullet is in the air. From that point, you need to hit the bullet enough times with your radar to be able to aim your laser at it, and THEN you'd need to "zap" the bullet with your laser long enough to do something about it.
And meanwhile it's not that hard to make the bullet go twice as fast, or to fire five bullets at once. (Combine those two and you're fucked.)