The American cellular telephone market has evolved differently than the rest of the world. In Europe and Japan, you (gerneally, there are exceptions) go buy a nice phone or a cheap phone; whatever has what you need. You can expect to pay from $50 to over $500 for a phone, depending on the features you want.
Compare it to buyinga PDA or a laptop computer.
Then, you went and picked a phone plan you want and they gave you the account information in a SIM card, which you put in whatever phone you got and you're off to the races.
But in the US, phone prices were deemed too high to make good inroads, so providers subsidised the cost of the phones. So you buy your service and it comes with a "free" phone, or a "$30" phone.
When someone's phone breaks, they take it in and find that to get a new phone, they will have to pay over $100 for essentially the same model phone. Outrage ensues!;-)
Of course, the subsidising didn't work out exactly well because people got unhappy with some aspect of the service and left for another company. That's where the 1- and 2-year contracts started coming in, so the providers could recoup the costs of subsidising the phone.
In the mean-time, US cellular phone customers have come to believe that cell phones truely cost around $30-$50 and balk at paying what amounts to actual retail price for one. It doesn't help that many of these cell phones look and feel like $30 pieces of electronics rather than the $180+ pieces of highly engineered hardware that they really are.
105 km is a good ways off. But Amateur Radio operators have been getting better than this with their voice transmissions (and possibly digital) on frequencies from 50 MHz to 10 GHz at the 2003 September VHF QSO Party.
Our university station was making contacts on frequencies greater than 2.4 GHz for distances longer than 200 miles. Contrary to common sense, Line-of-Sight is not necessarily required to get microwave transmissions to work over long distances. But they're very weak;-)
If you do that, you might notice that you're sending the same bits as the source file. It doesn't make it any more legal if you wrap file transfer with some question-answer-protocol-which-doesn't-change-the- way-the-file-is-transfered.
Another simple alternative is to "ask" is bit n a 0? In that way, the server sends you the whole file bitwise-inverted. Doesn't sound like a way around the law either. (ignoring the fact that the intent is what is really looked at, not necessarily the methods).
Extending it further and all you're seeming to do is encrypt or otherwise encode the file in question before sending it.
Those spam-catching tools work by doing a reverse-dns lookup of the IP address that is trying to send the mail. This is different than doing a "forward"-dns lookup.
This shouldn't have any effect on those spam-catching tools.
I know I'd be disappointed if a relative of mine was killed in a terrorist attach. But I doubt I would sue anyone over it.
I'm not sure what this country's fascination is with the need to assign blame to (and demand compensation from) every unfortunate thing that happens to them.
That's the lawyers fault? Funny, I make that the fault of the people for allowing such a law to exist. Change it if you don't like it.
For allowing such a law to exist? What law are we talking about? I didn't know that we had to create an actual law that says a private party can accuse another another private party of something.
The U.S. has the civil court system to provide a forum in which private parties can duke it out in a civilized manner that's binding. But I don't see how it is the fault of "the people" that some (laywers?) take selfish advantage of the system.
I don't know about you, but many of the 'well-to-do' folks I have run into who have nice cars are some of the cheapest people around when it comes to paying for things that nobody can see...
That's why you hear stories of folks who make millions of [currency] per year and pay nearly nothing in taxes (in the U.S.); why pay for it when you can't flaunt it!
Vacuum tubes are still used as the final amplification stage for TV and radio broadcast transmitters. They're the best thing able to handle the power efficiently, even today. Try building a semiconductor transistor with a gate width measured in centimeters (compared with microns); it's tough.
I thought that the only reverse engineering that was outlawed by the DMCA was if it was used for defeating some access/copy control for a copyrighted work.
The DMCA doesn't automatically make any reverse engineering illegal. The law is there for the benefit of copyright holders. That's why it's called the Digital Millenium *COPYRIGHT* Act.
I don't know... I find that the comments are now more interesting than the stories.
In the early days, yes, the stories were mostly interesting or relavent. These days there's too much stuff that I personally don't care about. That's not a problem really; it's not my website!;-)
But dessert comes with the comments. I had no idea there were so many folks out there who don't have a clue, yet insist they do. It's one thing to be ignorant and be aware of it, or even to be ignorant and not care about it, but I see so many posts in ignorance where the poster insists they know the subject!
The "good old days" were more interesting, but less comical.
I had a Maxtor 80G that had an intermittent motor failure. Sometimes it would just stop spinning after weeks of uptime (not the power-saving spin-down, it would make odd noises when trying to spin back up) and usually after that it would take about 20 power toggles to get the motor to get going. I cracked open the top to see what was going on and found that the drive kind of jerked when power was applied, but it just wouldn't get going. There was a small hole in the spindle bracket, so I stuck a small tool in the hole and gave the platters a good spin. They went right up! I put the lid back on (while it was running) and backed up the contents of the drive and ordered a new drive.
It was a fun process, but probably only because I didn't have vita data on the drive.
Yeah I guess market-ese is different than reality many times. Yes, the different modes operate on different bands (though it's only required by convention/law, not by technology).
There are several bands in the US, Europe, and Asia for cellular service; few overlap. CDMA isn't always at 1900.
I wonder if marketers and copy-writers just don't know the difference between band and mode or if they have devoted some "market research" to such things... Hmm.
Triple band doesn't mean the phone includes analog (though it doesn't preclude it). A band is a frequency range. If a phone will work with both digital and analog, it's touted as Dual Mode or Tri-Mode. Analog vs. Digital or Analog vs. CDMA vs. GSM are modes, not bands.
While it may help a little bit to put on an antenna tuned more closely to 2.4 GHz, the effect would be marginal. The problem isn't necessarily that the antenna isn't getting the signal good enough, it's that the receiver circuitry is less sensitive in the 2.4 GHz range.
It's very difficult to create a tuning circuit (which all receivers have) that is very sensitive across a wide range of frequencies. I would guess that this receiver is most sensitive in the VHF/UHF or even 800 MHz bands. From the specs, it looks like the upper end of the range for the R-3 is 2540 MHz (2.54 GHz), which isn't necessarily the clear-cut end of receiving capability for the product, it's just where the engineers (or marketers) decided to print the cutoff because the sensitivity drops off quickly somewhere around there.
The solution might be a 'transverter' device which essentially acts as another IF stage in the receiver, mixing all input signals with a fixed frequency. The result is several sidebands, at least one of which is offset from the input signal by the value of the fixed frequency.
Example: You want to see a video transmission on 2.450 GHz, but the receiver is not sensitive there. You build a little circuit that uses a diode to mix the incoming frequency with a 1000 MHz signal generated by a crystal (good luck finding a 1GHz crystal;-) ). Then you can tune your receiver to either 1.450 GHz (2.45 GHz - 1.00 GHz) and find a slightly weaker copy of the 2.45 GHz signal there. If the increased sensitivity of your receiver in the 1.45 GHz area is larger than the decrease in the signal strength by mixing (which is probably some calculable amount, but I don't want to take the time to figure it out...), then you will end up with a clearer picture of the 2.45 GHz video signal.
This technique is sometimes used by folks who really want to break US law and listen to cell-phone conversations. Nevermind that nowadays analog calls are nearly extinct. By law all receivers sold in the US must block tuning in of the cell-phone frequencies, which are around 850-900 MHz. (That's different these days with digital, but we're talking about analog.). Since nearly all receivers of FM audo use an IF (Intermediate Frequency, like the 1000 MHz signal we used above) of 10.7 MHz, users found they could tune to some multiple of 10.7 MHz below or above the cell phone frequencies and hear the 'images' of the calls. Nowadays scanner manufacturers extend those blocked frequencies to the image frequencies as well, so most folks are out-of-luck unless they build their own receiver for 850 MHz.
Whatever floats your boat. My favorite method is just to be a lazy American and eat lots of food. It's a tough procedure, but it sure makes the Zaurus so enjoyable to use.;-)
It wouldn't be possible to adapt an 802.11 card to receive the signals. The X-10 video is analog. The GNU-Radio software doesn't receive signals. It basically does the math to raw RF signals, which have been frequency-translated (called transverting) to a range that is able to be captured by a high-end data acquisition board. The 802.11 equipment isn't designed to pass along that raw data.
Perhaps one day there will be a bit of hardware that will allow us to upload DSP programs to it and have it able to display any bit of RF signals, but that day isn't here yet. It would be great to have a single little device that could be a wireless network card one hour, then a television receiver the next, cell phone, bluetooth, etc...
Antennas don't work that way. A signal will get into a directional antenna, even if the antenna isn't pointed at the signal source. It's signal strength will be weak, but it will still get in. Some of the signal will be direct, some with be due to "multipath" reflections off of the ground, and other objects.
So if you have the base station refuse connections mainly from the vertically pointed antenna, the base station may still accept the weak connection (as though it were a distant cell phone) from the side-pointed antennas.
I would guess that if you tried to use your cell phone from a plane, those base stations under the plane would not be used, since there is the whole metal body of the plane and the cargo holds under the passenger area. Your cell phone would be communicating with towers more along the horizon, and therefore you would be less vertically-oriented w.r.t. the connecting base station. Most of the signal attenuation with ground-based cell phone communications comes from buildings and vegetation. If you're high up, you can reach a very distant cell phone, since it's only the air providing attenuation of the signal. A very low-power signal can effect very long range communications when there aren't attenuation elements in the way.
Since most cell phone users are located near the ground anyway, the base station's antennas are designed to provide most of the signal toward the horizon or slightly below it, with very little actually radiating above the horizon line. This is , in effect, what you were proposing about "locking out" high altitude clients.
I think overall the problem isn't that great. Cell phones don't connect to every base station they can hear. They pick the strongest base station and then hold a few other strong ones "in reserve" for handoffs, registering with the base stations, but not reserving any extra channel space for them.
The fact that many people living in the vicinity of airports experience dropped calls and fast-busy signals may be due to the increased number of cell-phone users at airports in general as well as RF splatter and/or weak harmonics from airport radar.
Note that Nokia is a very diverse company and they don't just do cell phones. Most of their other products (that don't involve cell phones) are found mostly in Europe and include two-way radios, "mesh" networking nodes (a la the now defunct AT&T Broadband).
I was first hestant to install the OpenZaurus ROM on mine, having had it for only a few days. I took the plunge finally and the difference is quite astonishing, in my opinion.
One thing I noticed right off is that the GUI feels much faster and smoother than the stock Sharp ROM. The 'Patience' solitaire game has a card-flipping graphical cutesie and with the OZ ROM, it's definitely smoother.
Another change is that OpenSSH is pre-installed; a nice addition. I guess the main benefit is active development of the OZ system. It's good to know that you can really get in touch with the developers and get into real discussion about various features.
It's hard to really quantify, but just using the OZ ROM feels better, both from a PDA standpoint and a Linux-user standpoint. It's more familiar feeling.
It's not so much a special radio card as it is just any wide-banded data acquisition board and a little frequency-translation unit.
There is a "tuner" that multiplies the incoming radio signals by a variable frequency. When you mix two oscillating signals (by multiplication) you get harmonics. If the variable frequency is just a sine wave (i.e., not modulated with any information), then the harmonics are identical in modulation to the original, but at a difference frequency. The tuning box is used to bring various radio signals down to a frequency that can be digitized by any ordinary data acquisition board.
These data acquisition boards are designed to basically sample voltages of whatever is tied to their inputs, and to sample it very very quickly and very often. Since these boards (and computers also) are getting more advanced (i.e. faster), they are able to sample real radio frequencies (stuff in the ones of MHz ranges).
After you get the signal digitized, it's just a simple matter of writing software that mathematically performs the functions that all the circuitry in the 'old-fashioned' receivers would do with their capacitors, resistors, and inductors (and more).
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The American cellular telephone market has evolved differently than the rest of the world. In Europe and Japan, you (gerneally, there are exceptions) go buy a nice phone or a cheap phone; whatever has what you need. You can expect to pay from $50 to over $500 for a phone, depending on the features you want.
;-)
Compare it to buyinga PDA or a laptop computer.
Then, you went and picked a phone plan you want and they gave you the account information in a SIM card, which you put in whatever phone you got and you're off to the races.
But in the US, phone prices were deemed too high to make good inroads, so providers subsidised the cost of the phones. So you buy your service and it comes with a "free" phone, or a "$30" phone.
When someone's phone breaks, they take it in and find that to get a new phone, they will have to pay over $100 for essentially the same model phone. Outrage ensues!
Of course, the subsidising didn't work out exactly well because people got unhappy with some aspect of the service and left for another company. That's where the 1- and 2-year contracts started coming in, so the providers could recoup the costs of subsidising the phone.
In the mean-time, US cellular phone customers have come to believe that cell phones truely cost around $30-$50 and balk at paying what amounts to actual retail price for one. It doesn't help that many of these cell phones look and feel like $30 pieces of electronics rather than the $180+ pieces of highly engineered hardware that they really are.
105 km is a good ways off. But Amateur Radio operators have been getting better than this with their voice transmissions (and possibly digital) on frequencies from 50 MHz to 10 GHz at the 2003 September VHF QSO Party.
See some of their setups at http://www.arrl.org/contests/soapbox/?con_id=53.
Our university station was making contacts on frequencies greater than 2.4 GHz for distances longer than 200 miles. Contrary to common sense, Line-of-Sight is not necessarily required to get microwave transmissions to work over long distances. But they're very weak ;-)
If you do that, you might notice that you're sending the same bits as the source file. It doesn't make it any more legal if you wrap file transfer with some question-answer-protocol-which-doesn't-change-the- way-the-file-is-transfered.
Another simple alternative is to "ask" is bit n a 0? In that way, the server sends you the whole file bitwise-inverted. Doesn't sound like a way around the law either. (ignoring the fact that the intent is what is really looked at, not necessarily the methods).
Extending it further and all you're seeming to do is encrypt or otherwise encode the file in question before sending it.
Oops. This will bother spam-catching tools who verify that a the reported "from" address domain exists.
I was thinking of those mail servers who reject mail from IP addresses which do not have a reverse-dns entry.
Sorry.
Those spam-catching tools work by doing a reverse-dns lookup of the IP address that is trying to send the mail. This is different than doing a "forward"-dns lookup.
This shouldn't have any effect on those spam-catching tools.
Sounds okay to me :-)
I know I'd be disappointed if a relative of mine was killed in a terrorist attach. But I doubt I would sue anyone over it.
I'm not sure what this country's fascination is with the need to assign blame to (and demand compensation from) every unfortunate thing that happens to them.
I blame (hehe) it on greed.
It's unfortunate that those few fools who make the most noise set the prevailing view of the U.S.
;-)
Though it might be interesting to see a trial where the plaintiffs are corpses (the victims of the attacks).
For allowing such a law to exist? What law are we talking about? I didn't know that we had to create an actual law that says a private party can accuse another another private party of something.
The U.S. has the civil court system to provide a forum in which private parties can duke it out in a civilized manner that's binding. But I don't see how it is the fault of "the people" that some (laywers?) take selfish advantage of the system.
I don't know about you, but many of the 'well-to-do' folks I have run into who have nice cars are some of the cheapest people around when it comes to paying for things that nobody can see...
That's why you hear stories of folks who make millions of [currency] per year and pay nearly nothing in taxes (in the U.S.); why pay for it when you can't flaunt it!
Vacuum tubes are still used as the final amplification stage for TV and radio broadcast transmitters. They're the best thing able to handle the power efficiently, even today. Try building a semiconductor transistor with a gate width measured in centimeters (compared with microns); it's tough.
I thought that the only reverse engineering that was outlawed by the DMCA was if it was used for defeating some access/copy control for a copyrighted work.
The DMCA doesn't automatically make any reverse engineering illegal. The law is there for the benefit of copyright holders. That's why it's called the Digital Millenium *COPYRIGHT* Act.
I don't know... I find that the comments are now more interesting than the stories.
;-)
In the early days, yes, the stories were mostly interesting or relavent. These days there's too much stuff that I personally don't care about. That's not a problem really; it's not my website!
But dessert comes with the comments. I had no idea there were so many folks out there who don't have a clue, yet insist they do. It's one thing to be ignorant and be aware of it, or even to be ignorant and not care about it, but I see so many posts in ignorance where the poster insists they know the subject!
The "good old days" were more interesting, but less comical.
I had a Maxtor 80G that had an intermittent motor failure. Sometimes it would just stop spinning after weeks of uptime (not the power-saving spin-down, it would make odd noises when trying to spin back up) and usually after that it would take about 20 power toggles to get the motor to get going. I cracked open the top to see what was going on and found that the drive kind of jerked when power was applied, but it just wouldn't get going. There was a small hole in the spindle bracket, so I stuck a small tool in the hole and gave the platters a good spin. They went right up! I put the lid back on (while it was running) and backed up the contents of the drive and ordered a new drive.
It was a fun process, but probably only because I didn't have vita data on the drive.
Yeah I guess market-ese is different than reality many times. Yes, the different modes operate on different bands (though it's only required by convention/law, not by technology).
There are several bands in the US, Europe, and Asia for cellular service; few overlap. CDMA isn't always at 1900.
I wonder if marketers and copy-writers just don't know the difference between band and mode or if they have devoted some "market research" to such things... Hmm.
Triple band doesn't mean the phone includes analog (though it doesn't preclude it). A band is a frequency range. If a phone will work with both digital and analog, it's touted as Dual Mode or Tri-Mode. Analog vs. Digital or Analog vs. CDMA vs. GSM are modes, not bands.
While it may help a little bit to put on an antenna tuned more closely to 2.4 GHz, the effect would be marginal. The problem isn't necessarily that the antenna isn't getting the signal good enough, it's that the receiver circuitry is less sensitive in the 2.4 GHz range.
;-) ). Then you can tune your receiver to either 1.450 GHz (2.45 GHz - 1.00 GHz) and find a slightly weaker copy of the 2.45 GHz signal there. If the increased sensitivity of your receiver in the 1.45 GHz area is larger than the decrease in the signal strength by mixing (which is probably some calculable amount, but I don't want to take the time to figure it out...), then you will end up with a clearer picture of the 2.45 GHz video signal.
It's very difficult to create a tuning circuit (which all receivers have) that is very sensitive across a wide range of frequencies. I would guess that this receiver is most sensitive in the VHF/UHF or even 800 MHz bands. From the specs, it looks like the upper end of the range for the R-3 is 2540 MHz (2.54 GHz), which isn't necessarily the clear-cut end of receiving capability for the product, it's just where the engineers (or marketers) decided to print the cutoff because the sensitivity drops off quickly somewhere around there.
The solution might be a 'transverter' device which essentially acts as another IF stage in the receiver, mixing all input signals with a fixed frequency. The result is several sidebands, at least one of which is offset from the input signal by the value of the fixed frequency.
Example: You want to see a video transmission on 2.450 GHz, but the receiver is not sensitive there. You build a little circuit that uses a diode to mix the incoming frequency with a 1000 MHz signal generated by a crystal (good luck finding a 1GHz crystal
This technique is sometimes used by folks who really want to break US law and listen to cell-phone conversations. Nevermind that nowadays analog calls are nearly extinct. By law all receivers sold in the US must block tuning in of the cell-phone frequencies, which are around 850-900 MHz. (That's different these days with digital, but we're talking about analog.). Since nearly all receivers of FM audo use an IF (Intermediate Frequency, like the 1000 MHz signal we used above) of 10.7 MHz, users found they could tune to some multiple of 10.7 MHz below or above the cell phone frequencies and hear the 'images' of the calls. Nowadays scanner manufacturers extend those blocked frequencies to the image frequencies as well, so most folks are out-of-luck unless they build their own receiver for 850 MHz.
And just to complicate matters, Yahoo Maps says that the distance from Edinburg, TX to R[h]ome, TX is 514 miles...
Whatever floats your boat. My favorite method is just to be a lazy American and eat lots of food. It's a tough procedure, but it sure makes the Zaurus so enjoyable to use. ;-)
Maybe you should look into some fatter thumbs. I am not a small person, so my big thumb fits rather well over the whole direction-pad. ;-)
It wouldn't be possible to adapt an 802.11 card to receive the signals. The X-10 video is analog. The GNU-Radio software doesn't receive signals. It basically does the math to raw RF signals, which have been frequency-translated (called transverting) to a range that is able to be captured by a high-end data acquisition board. The 802.11 equipment isn't designed to pass along that raw data.
Perhaps one day there will be a bit of hardware that will allow us to upload DSP programs to it and have it able to display any bit of RF signals, but that day isn't here yet. It would be great to have a single little device that could be a wireless network card one hour, then a television receiver the next, cell phone, bluetooth, etc...
Antennas don't work that way. A signal will get into a directional antenna, even if the antenna isn't pointed at the signal source. It's signal strength will be weak, but it will still get in. Some of the signal will be direct, some with be due to "multipath" reflections off of the ground, and other objects.
So if you have the base station refuse connections mainly from the vertically pointed antenna, the base station may still accept the weak connection (as though it were a distant cell phone) from the side-pointed antennas.
I would guess that if you tried to use your cell phone from a plane, those base stations under the plane would not be used, since there is the whole metal body of the plane and the cargo holds under the passenger area. Your cell phone would be communicating with towers more along the horizon, and therefore you would be less vertically-oriented w.r.t. the connecting base station. Most of the signal attenuation with ground-based cell phone communications comes from buildings and vegetation. If you're high up, you can reach a very distant cell phone, since it's only the air providing attenuation of the signal. A very low-power signal can effect very long range communications when there aren't attenuation elements in the way.
Since most cell phone users are located near the ground anyway, the base station's antennas are designed to provide most of the signal toward the horizon or slightly below it, with very little actually radiating above the horizon line. This is , in effect, what you were proposing about "locking out" high altitude clients.
I think overall the problem isn't that great. Cell phones don't connect to every base station they can hear. They pick the strongest base station and then hold a few other strong ones "in reserve" for handoffs, registering with the base stations, but not reserving any extra channel space for them.
The fact that many people living in the vicinity of airports experience dropped calls and fast-busy signals may be due to the increased number of cell-phone users at airports in general as well as RF splatter and/or weak harmonics from airport radar.
If I am wrong, please correct me.
Note that Nokia is a very diverse company and they don't just do cell phones. Most of their other products (that don't involve cell phones) are found mostly in Europe and include two-way radios, "mesh" networking nodes (a la the now defunct AT&T Broadband).
Check it out at http://www.nokia.com/networks/product_catalog
I was first hestant to install the OpenZaurus ROM on mine, having had it for only a few days. I took the plunge finally and the difference is quite astonishing, in my opinion.
One thing I noticed right off is that the GUI feels much faster and smoother than the stock Sharp ROM. The 'Patience' solitaire game has a card-flipping graphical cutesie and with the OZ ROM, it's definitely smoother.
Another change is that OpenSSH is pre-installed; a nice addition. I guess the main benefit is active development of the OZ system. It's good to know that you can really get in touch with the developers and get into real discussion about various features.
It's hard to really quantify, but just using the OZ ROM feels better, both from a PDA standpoint and a Linux-user standpoint. It's more familiar feeling.
It's not so much a special radio card as it is just any wide-banded data acquisition board and a little frequency-translation unit.
There is a "tuner" that multiplies the incoming radio signals by a variable frequency. When you mix two oscillating signals (by multiplication) you get harmonics. If the variable frequency is just a sine wave (i.e., not modulated with any information), then the harmonics are identical in modulation to the original, but at a difference frequency. The tuning box is used to bring various radio signals down to a frequency that can be digitized by any ordinary data acquisition board.
These data acquisition boards are designed to basically sample voltages of whatever is tied to their inputs, and to sample it very very quickly and very often. Since these boards (and computers also) are getting more advanced (i.e. faster), they are able to sample real radio frequencies (stuff in the ones of MHz ranges).
After you get the signal digitized, it's just a simple matter of writing software that mathematically performs the functions that all the circuitry in the 'old-fashioned' receivers would do with their capacitors, resistors, and inductors (and more).
That's pretty much how it works.
Who cares what happens when you mix gasoline and soap together and strike a match? The same thing happens with just gasoline.
;-)
Boom.
(Yes, I know what dish soap does to gasoline.)