Check out the longwave transmitter/antenna setup at NIST's WWV in Colorado. While in this case the towers aren't "hot", NIST does employ several towers in order to hold up this capacitance hat. This transmitter operates on 60kHz!
I would have thought that a 200' antenna on top of a 200' tower, with the tower as the 'ground plane' would act as a vertically-oriented dipole and would have half-decent propogation... Assuming there were no ground (dirt) in the vicinity. Which is impossible. You're right;-)
IAAAmateurRadioOperator (and an engineer, just not a radio engineer, though the field is fascinating!)
Many old AM transmitter stations used the whole tower as the antenna, simply because the wavelength at such low frequencies was so long it would be impractical to stick a 200 ft. antenna on top of a 200 ft. tower.
They just load the tower at the base and the whole thing radiates!
The great thing about antenna design and RF theory is that all of the design happens in the mathematics domain, so all designs are infinitely scaleable. The only hitch may be in manufacturing, since small designs can be affected by molecular structure (or at least moreso than larger designs...)
The articles did mention that it could be used in the frequency bands that cell phones use, so you're in luck!
And actually, it would improve BOTH battery life and reception, since receiving a signal doesn't require any more or less power based on the antenna or incoming signal strength (excepting preamps). All other things being equal, if you decrease the transmit power, increase the antenna gain (which gives a gain for both receive and transmit), then you use less power overall, but can output an equivalent signal.
Improved reception is an unrelated (to power consumption) bonus.
I'd like to see a card that (as mentioned in the comments elsewhere) only activates its chip when the user presses some button, or some similar activity. That allows the user (consumer) to be in control of when the card is used.
Of course, Smart Cards already can do things like this, but I suppose we can't just use existing, proven methods...;-)
Re:Tell me I'm wrong
on
RFID MasterCard
·
· Score: 2, Informative
In that case, the RFID chip would still only output it's regular power, since the capacitor in it has a limited capacity. There would be no way to get the RFID chip to emit more power than it was manufactured to.
How would that decrease the security of the challenge-response method?
The intial string "to be encrypted" is random.
Re:Tell me I'm wrong
on
RFID MasterCard
·
· Score: 5, Informative
The power does come from the reader in the form of a low frequency, unmodulated RF signal (a sine wave) around 140 kHz (a very, very low frequency). An antenna on the RFID chip absorbs this RF energy into a capacitive component and the energy from each pulse of the low frequency "Activates" the chip to emit its information on a higher frequency (varies, from 400 MHz to 3 GHz, but mostly in the 400 MHz or 920 MHz bands, depending on the chip design).
The power with which the chip emits its information is dependent on the size of the capacitor on it, so feeding a higher "power beam" to it will not increase the output power.
However, RF energy decreases as the distance from the radiator increases (inverse square law), but does not technically (theoretically) go away completely at any distance from the radiator. If your subversive reader had a higher-gain receiving antenna than the official reader, then you would be able to read the data farther away than one inch.
Note that RFID chips have come a long way since the beginning and now can perform whole two-way transactions during each pulse of activity. The devices could implement a challenge-response type of authentication. The chip sends a string, the reader encrypts it with the secret code, and sends it back to the chip which checks to see if the string is encrypted correctly. If it is, then it sends the data (also enrypted) to the reader, all in one pulse from the "power beam".
While nothing can be totally secure AND also accessible to everyone, the challenge-response system is practical and effective (some mail servers use it so you can log into your mail server over an unencrypted channel without revealing your password).
Just picking nits, but if there are 1000g in 1kg, then 35% should be 350g of salt in 1000g of saltwater, or you should say 3.5% = 35g of salt in 1000g of salt water.
Likewise, 1 metric ton (1000kg) of sea-water at 35% (as you say) would be 350kg of salt, not 35kg.
We normally wouldn't even need to use the Reserves except that a prior administration decided we didn't need as large of an armed forces and proceeded to downsize the military.
There is no shortage of folks willing to enlist, but the military branches just weren't able to take them all due to policies limiting the size of the military.
Then, the current administration started mobilizing large numbers of troops and therefore, we needed to dip into the Reserve. Unfortunately, the Reserves are not as well trained as full-time soldiers.
I think the reason that there is even a "Door Close" button on elevators is for the firefighters to gain full control of the elevator.
If you notice in elevators (at least in the U.S.) there is a keyslot where you can switch the elevator from Normal to Off or Fire mode. In Fire mode, the elevator doors don't open until you press the door-open button and they don't close until you press the door-close button.
So, the door close button doesn't normally work, but it's there for a reason.
I think that's one reason why the seperating of DSL and the POTS line is happening so slowly (or nonexistently) in the U.S.
I can just see the phone companies using the subscriber number as the identifier for everything account-related and they just don't want or (think they) can't afford to retool it to something else.
Silly little technical reasons why good ideas don't happen...
I didn't miss it. The point was that if the signal is out there, it can be decoded. Just about any technology on signal processing is first written about in research papers before it gets implemented commercially.
If you're an IEEE Signal Processing Society member, check out the proceedings of the ICASSP conferences. Lots of information on OFDM transmission techniques.
And as another poster mentioned, with projects like GNUradio around, it's a matter of writing a decoder to the raw data acquired. I am not saying a police scanner would help, but the technology used for radio receiver circuits is certainly no secret.
It's like hacking (def: figuring out how things work) the airwaves.
Security:
Nextel Wireless Broadband(TM) is as secure as DSL or Cable. In addition, it is a broadband access network based on a proprietary signal processing technology operated over licensed spectrum. Designed across multiple layers, the broadband system prevents unauthorized entities from gaining network access. Depending upon your needs, additional security layers can also be enabled through VPN clients for secure corporate access or SSL for secure Internet transactions. With Nextel Wireless Broadband(TM), you can unwire the Internet and connect to all of your favorite VPN/SSL-secured applications - with confidence.
I find it amusing. They say that is it secure because it's proprietary technology on a licenced radio service so no one can "gain unauthorized network access". I have several radios and scanners that can certainly receive frequencies that this operates on, if not transmit as well. One does not have to "gain unauthorized network access" just to listen.
The closing sentence basically says "enjoy our service but take your own precautions about secure access."
I'm not saying it's insecure (what is secure, truly!?). I do take a dislike to the reassurance of security with the disclaimer that any security should be provided by yourself buried in the rhetoric.
Digital cash is not a very good solution. Why throw technology at something that could be solved by going back to simple metal coins for currency. While not foolproof, it's certainly easier to implement than "secure and anonymous digital cash".
The downsides are clear though (heavy, bulky, uneconomical to produce in many denominations, etc.) which is why we moved away from it.
The low ID people don't care about Karma. When we got account, there was no such thing. We just don't feel like spouting off pages of junk about every story.;-)
What I would like to know is, what are the wires that follow train tracks? Ancient telegraph lines perhaps? Who owns them? Are they still used? If not, why the hell are they still there?
At least in Rural Texas, where you see short (10 feet high) poles strung with wires, half rotted or fallen over, they were telegraph cables. The rails are still used, but the cables aren't.
Communication to/from the train is done by radio and communication between rail stations is done by regular telephone.
As I take the Constitution regarding copyrights is just as stated 'securing for limited times the exclusive right to their work'.
That's it. And apparently SCO thinks that 'exclusive right to their work' means that an author of a work cannot choose to give away the work.
Why does SCO think that copyright laws restrict authors from doing whatever the hell they want with their own creations? I think this is the first flaw in their 'open letter'. It's all based on the idea that Congress says you have to keep your own work secret for x years.
I'm not sure of that. I think the issue is that there was too little regulation in the US mobile market early on, which led to fragmented standards and the mindset in the providers that they offered a service that was unique.
In Europe and Japan, most folks don't need to know what protocol is used by their phones to communicate with the network because it's a standard.
In the US, everyone *should* know, but they don't because the providers never bring it up for fear of confusing folks (which it would). CDMA, TDMA, GSM, AMPS, GPRS, Dual-mode, Tri-band, EDGE, G2, G3, G2.5, WTF?!!
I've heard some folks in one of the local cell-phone stores here in TX use tri-mode and tri-band interchangeably. The sellers don't even know. All that matters to them is telling the customer that "Tri means 3 and dual means 2 and 3 is bigger than 2!!".
And then there's the whole "locked handset" business discussed elsewhere in the article. I did and internship at Nokia one summer and learned for the first time that providers who purchase the large amounts of handsets from Nokia request the ability to have the phone only connect with one network, even though they technically could connect with many more. To protect their investment. Now that adds to the confusion of the customer. "What do you mean I can't get service with Company X and my Phone A that I still have from Company Y? My buddy has service with Company X and has Phone A and it works fine. Why won't MY phone work!?"
Also, the European market may be saturated, but I doubt it's because it's been around longer than the US cell market. The US cell market has been around longer, but has vast expanses of rural places who now demand cell service.
Slashdot Mirror
And this "hat" isn't made of tinfoil! ;-)
Check out the longwave transmitter/antenna setup at NIST's WWV in Colorado. While in this case the towers aren't "hot", NIST does employ several towers in order to hold up this capacitance hat. This transmitter operates on 60kHz!
I would have thought that a 200' antenna on top of a 200' tower, with the tower as the 'ground plane' would act as a vertically-oriented dipole and would have half-decent propogation... Assuming there were no ground (dirt) in the vicinity. Which is impossible. You're right ;-)
IAAAmateurRadioOperator (and an engineer, just not a radio engineer, though the field is fascinating!)
Many old AM transmitter stations used the whole tower as the antenna, simply because the wavelength at such low frequencies was so long it would be impractical to stick a 200 ft. antenna on top of a 200 ft. tower.
They just load the tower at the base and the whole thing radiates!
The great thing about antenna design and RF theory is that all of the design happens in the mathematics domain, so all designs are infinitely scaleable. The only hitch may be in manufacturing, since small designs can be affected by molecular structure (or at least moreso than larger designs...)
The articles did mention that it could be used in the frequency bands that cell phones use, so you're in luck!
And actually, it would improve BOTH battery life and reception, since receiving a signal doesn't require any more or less power based on the antenna or incoming signal strength (excepting preamps). All other things being equal, if you decrease the transmit power, increase the antenna gain (which gives a gain for both receive and transmit), then you use less power overall, but can output an equivalent signal.
Improved reception is an unrelated (to power consumption) bonus.
You're right, that's a possiblity. A real one!
;-)
I'd like to see a card that (as mentioned in the comments elsewhere) only activates its chip when the user presses some button, or some similar activity. That allows the user (consumer) to be in control of when the card is used.
Of course, Smart Cards already can do things like this, but I suppose we can't just use existing, proven methods...
In that case, the RFID chip would still only output it's regular power, since the capacitor in it has a limited capacity. There would be no way to get the RFID chip to emit more power than it was manufactured to.
How would that decrease the security of the challenge-response method?
The intial string "to be encrypted" is random.
The power does come from the reader in the form of a low frequency, unmodulated RF signal (a sine wave) around 140 kHz (a very, very low frequency). An antenna on the RFID chip absorbs this RF energy into a capacitive component and the energy from each pulse of the low frequency "Activates" the chip to emit its information on a higher frequency (varies, from 400 MHz to 3 GHz, but mostly in the 400 MHz or 920 MHz bands, depending on the chip design).
The power with which the chip emits its information is dependent on the size of the capacitor on it, so feeding a higher "power beam" to it will not increase the output power.
However, RF energy decreases as the distance from the radiator increases (inverse square law), but does not technically (theoretically) go away completely at any distance from the radiator. If your subversive reader had a higher-gain receiving antenna than the official reader, then you would be able to read the data farther away than one inch.
Note that RFID chips have come a long way since the beginning and now can perform whole two-way transactions during each pulse of activity. The devices could implement a challenge-response type of authentication. The chip sends a string, the reader encrypts it with the secret code, and sends it back to the chip which checks to see if the string is encrypted correctly. If it is, then it sends the data (also enrypted) to the reader, all in one pulse from the "power beam".
While nothing can be totally secure AND also accessible to everyone, the challenge-response system is practical and effective (some mail servers use it so you can log into your mail server over an unencrypted channel without revealing your password).
I think the government is mandating Digital TV, not HDTV. Digital TV doesn't have to come in HD format and HD doesn't have to be digital.
Helter Skelter!!!
(yes, mod me down... I don't care. Props to the quote of one of the greatest bands ever!)
Just picking nits, but if there are 1000g in 1kg, then 35% should be 350g of salt in 1000g of saltwater, or you should say 3.5% = 35g of salt in 1000g of salt water.
Likewise, 1 metric ton (1000kg) of sea-water at 35% (as you say) would be 350kg of salt, not 35kg.
We normally wouldn't even need to use the Reserves except that a prior administration decided we didn't need as large of an armed forces and proceeded to downsize the military.
There is no shortage of folks willing to enlist, but the military branches just weren't able to take them all due to policies limiting the size of the military.
Then, the current administration started mobilizing large numbers of troops and therefore, we needed to dip into the Reserve. Unfortunately, the Reserves are not as well trained as full-time soldiers.
Ever seen the movie "Black Hawk Down"? Bill did that.
I think the reason that there is even a "Door Close" button on elevators is for the firefighters to gain full control of the elevator.
If you notice in elevators (at least in the U.S.) there is a keyslot where you can switch the elevator from Normal to Off or Fire mode. In Fire mode, the elevator doors don't open until you press the door-open button and they don't close until you press the door-close button.
So, the door close button doesn't normally work, but it's there for a reason.
I think that's one reason why the seperating of DSL and the POTS line is happening so slowly (or nonexistently) in the U.S.
I can just see the phone companies using the subscriber number as the identifier for everything account-related and they just don't want or (think they) can't afford to retool it to something else.
Silly little technical reasons why good ideas don't happen...
Well, if you've been harassing them "for a while now", it appears that they get all of your money.
I didn't miss it. The point was that if the signal is out there, it can be decoded. Just about any technology on signal processing is first written about in research papers before it gets implemented commercially.
If you're an IEEE Signal Processing Society member, check out the proceedings of the ICASSP conferences. Lots of information on OFDM transmission techniques.
And as another poster mentioned, with projects like GNUradio around, it's a matter of writing a decoder to the raw data acquired. I am not saying a police scanner would help, but the technology used for radio receiver circuits is certainly no secret.
It's like hacking (def: figuring out how things work) the airwaves.
Check out their "Features" list under the Personal category at http://www.nextelbroadband.com/pu_features.html
I find it amusing. They say that is it secure because it's proprietary technology on a licenced radio service so no one can "gain unauthorized network access". I have several radios and scanners that can certainly receive frequencies that this operates on, if not transmit as well. One does not have to "gain unauthorized network access" just to listen.
The closing sentence basically says "enjoy our service but take your own precautions about secure access."
I'm not saying it's insecure (what is secure, truly!?). I do take a dislike to the reassurance of security with the disclaimer that any security should be provided by yourself buried in the rhetoric.
Digital cash is not a very good solution. Why throw technology at something that could be solved by going back to simple metal coins for currency. While not foolproof, it's certainly easier to implement than "secure and anonymous digital cash".
;-)
The downsides are clear though (heavy, bulky, uneconomical to produce in many denominations, etc.) which is why we moved away from it.
I say bring back the $20 gold coin!
heh. And wouldn't you know I visited the site for at least a month before I signed up for an account.
(yes, this is off topic.)
The low ID people don't care about Karma. When we got account, there was no such thing. We just don't feel like spouting off pages of junk about every story. ;-)
Don't you mean '...for dislosing that dead software operating system is "3 times better"...'
;-)
At least in Rural Texas, where you see short (10 feet high) poles strung with wires, half rotted or fallen over, they were telegraph cables. The rails are still used, but the cables aren't.
Communication to/from the train is done by radio and communication between rail stations is done by regular telephone.
Why does SCO think that copyright laws restrict authors from doing whatever the hell they want with their own creations? I think this is the first flaw in their 'open letter'. It's all based on the idea that Congress says you have to keep your own work secret for x years.
Absurd.
I'm not sure of that. I think the issue is that there was too little regulation in the US mobile market early on, which led to fragmented standards and the mindset in the providers that they offered a service that was unique.
In Europe and Japan, most folks don't need to know what protocol is used by their phones to communicate with the network because it's a standard.
In the US, everyone *should* know, but they don't because the providers never bring it up for fear of confusing folks (which it would). CDMA, TDMA, GSM, AMPS, GPRS, Dual-mode, Tri-band, EDGE, G2, G3, G2.5, WTF?!!
I've heard some folks in one of the local cell-phone stores here in TX use tri-mode and tri-band interchangeably. The sellers don't even know. All that matters to them is telling the customer that "Tri means 3 and dual means 2 and 3 is bigger than 2!!".
And then there's the whole "locked handset" business discussed elsewhere in the article. I did and internship at Nokia one summer and learned for the first time that providers who purchase the large amounts of handsets from Nokia request the ability to have the phone only connect with one network, even though they technically could connect with many more. To protect their investment. Now that adds to the confusion of the customer. "What do you mean I can't get service with Company X and my Phone A that I still have from Company Y? My buddy has service with Company X and has Phone A and it works fine. Why won't MY phone work!?"
Also, the European market may be saturated, but I doubt it's because it's been around longer than the US cell market. The US cell market has been around longer, but has vast expanses of rural places who now demand cell service.