His graph is erroneously labeled in dB, which is an arbitrary scale, whereas it ought to be labeled in dBm, which is received signal strength.
In case you're wondering,the B is a Bel, which is a factor of 10. A dB is a deciBel, which is 1/10 of a Bel. dBm is decibels relative to a milliwatt of signal strength.
The problem is that they aren't allowed to use the upper half of the phone due to cranial exposure limits, so the antenna has to be on the bottom. Perhaps they could have it choose the best lower corner antenna. Or they could put in an actual antenna mast on the top, and it would work very well, and people would stop bitching about lousy reception. Wait, what was I thinking? This is the company that made the round mouse.
I don't think that Mark Zuckerberg is under the jurisdiction of the Pakistani police. He doesn't live there, he isn't a citizen of Pakistan, he didn't even commit this infraction himself.
Of course, I am not a Pakistani lawyer, so don't take this as legal advice, Mark.
I hear you. Offshoring production is bad for the world.
I produce a consumer electronics product in the USA using my own manual labor. It pays very well, because I price my product so that I make a decent wage ($200/hour) performing the menial assembly task. However, I am working today (a holiday) to keep up with demand.
I read in a post above that Apple pays 2.5%, now 3% with the raise, of the iPad's selling price for assembly labor. That could be raised to 20% and the product would still sell as well, and the workers would be ten times as rich.
It's all politics. There's the environmental impact problem. The folks who arranged for our underground power line really screwed up by not putting a fiber in the same trench; now it's virtually impossible to get the Forest Service to permit additional work. Four words: Mount Graham Red Squirrels!
I work on millimeter- and submillmeter-wave frequency radio telescopes in Arizona that occasionally do VLBI runs at 1.3mm (230 GHz). We don't have anything like a 1Gbps data link; it's more like 10 Mbps. It's hard to get the phone company to install a fiber cable run up a mountain.
Our VLBI data are stored on hard disks at a rate of ~1 Gbps,
then correlated later on some big computer back east. We have to wait days to learn if interference fringes were detected!
The magnetic domains and track widths are on the order of 20 nanometers these days, so considering that the average molecule is a nanometer or two in diameter, disks will have to use some other method of storage to get beyond a petabyte per drive.
That video of the leaking pipe shows stuff coming out of it at a rate of about two pipe diameters per second, if you just watch how fast the moving stuff moves. Some simple math puts that flow rate, for the 20 inch diameter pipe that it's said to be, at 80,000 bbl/day.
The math: the pipe area is ~2 sq ft, the flow rate is ~3 ft/second, the volume per second is 6 cu ft, which is about 45 gallons or one barrel per second. That's ~80k bbl/day.
If my math is wrong, please show me how it's wrong. It's the same math that the univ professors are using.
So buy a Prius. It has the same mechanism in it. The two drive sources are the gasoline engine and a motor-generator MG1. See an animation of it here: http://eahart.com/prius/psd/
Not just that, but they are visually interesting plot tools. Real computer use is too visually dull to be used in a Hollywood movie. And the text on the screen is much to small to resolve when the movie is shown on TV, so Hollywood makes the words really big. Maybe that will change when Blu-Ray becomes standard.
The payload is the expensive part. The folks in the office next to mine are building a similar telescope for TeraHertz observations. The screws don't cost $150 each as an earlier commenter suggested, but the TeraHertz components are rather pricey, since the small market for that stuff results in one-digit serial numbers. And it uses liquid helium to cool the receiver. And they aren't building it sturdily enough to handle being dragged across parked cars! (They may change their design after watching the video...)
Our homebrew machine could play chess, play Star Trek, act as a word processor (my mom typed her thesis on it), we played 3D stereo Space War on an oscilloscope dot display, etc. It could do amazing things, all in 4K of RAM and a homemade 32x16 character display.
You think you had it hard waiting for paper tape? My brother wrote his own 2K Tiny Basic interpreter for the M6800 from scratch, stored on reel-to-reel tape. We wanted a printer; Dad brought home a Friden Flexowriter and invited us to make it talk. We did. We were lazy enough to ask for a 4K RAM kit with a genuine PC board for Christmas, since wire-wrapping 32 chips was a bit tedious.
The Altair really got the hobby computer market going. It was by no means perfect, but it was something that a lot of people were hungry for. I had the thrill of working in a retail computer store in 1978 when the IMSAI and Apple were going head-to-head. [IMSAI is a spelling error in this text entry box, which tells you who won.]
Notice that sometimes the columns of type gaps between them or are run together. This printer wasn't nearly as well made as the American behemoths of the sixties.
Noise is proportional to the square root of bandwidth. The signal-to-noise ratio determines the bandwidth of the signal that can be demodulated. So if they're transmitting a 1Mbps modulation scheme, then the bandwidth would be several tens of kHz and carrier has to be strong enough to present a reasonably noise-free signal of those tens of kHz bandwidth to the demodulator.
On the other hand, if it's a 3bps modulation scheme, then the carrier could be nearly invisible and still have the necessary S/N to present a useful signal to the demodulator, since the receiver bandwidth can be reduced to under 1 Hz.
So unless you know the modulation bandwidth, it's impossible to say how much carrier you need to recover the modulation.
Whether the carrier is strong enough depends on the bandwidth of the signal. The downlink apparently (Google is being stubborn) uses phase shift keying at a selectable data rate from a few bps to a couple hundred kpbs, depending on conditions.
So you'd have to have a suitable demodulator to get the data, and the big message given by the fine article is that you'd need a much bigger dish to get enough S/N to have anything to demodulate.
I work on radio telescopes, not deep space monitors, so I don't know squat about the demodulation.
Slashdot Mirror
His graph is erroneously labeled in dB, which is an arbitrary scale, whereas it ought to be labeled in dBm, which is received signal strength.
In case you're wondering,the B is a Bel, which is a factor of 10. A dB is a deciBel, which is 1/10 of a Bel. dBm is decibels relative to a milliwatt of signal strength.
Danger is in the eye of the beholder. Anyone with a solar death ray is blind to danger.
The problem is that they aren't allowed to use the upper half of the phone due to cranial exposure limits, so the antenna has to be on the bottom. Perhaps they could have it choose the best lower corner antenna.
Or they could put in an actual antenna mast on the top, and it would work very well, and people would stop bitching about lousy reception.
Wait, what was I thinking? This is the company that made the round mouse.
I don't think that Mark Zuckerberg is under the jurisdiction of the Pakistani police. He doesn't live there, he isn't a citizen of Pakistan, he didn't even commit this infraction himself.
Of course, I am not a Pakistani lawyer, so don't take this as legal advice, Mark.
The story says that not all carriers encode it like this; some might have used such advanced encryption techniques as ROT13.
I wonder if the folks who do network design at AT&T have any idea at all that their job is related to security.
Hey, it worked for the Cold War, so how about using it here?
I hear you. Offshoring production is bad for the world.
I produce a consumer electronics product in the USA using my own manual labor. It pays very well, because I price my product so that I make a decent wage ($200/hour) performing the menial assembly task. However, I am working today (a holiday) to keep up with demand.
I read in a post above that Apple pays 2.5%, now 3% with the raise, of the iPad's selling price for assembly labor. That could be raised to 20% and the product would still sell as well, and the workers would be ten times as rich.
They do. The folks in the lab next to my office just built such a receiver.
It's all politics. There's the environmental impact problem. The folks who arranged for our underground power line really screwed up by not putting a fiber in the same trench; now it's virtually impossible to get the Forest Service to permit additional work. Four words: Mount Graham Red Squirrels!
I work on millimeter- and submillmeter-wave frequency radio telescopes in Arizona that occasionally do VLBI runs at 1.3mm (230 GHz). We don't have anything like a 1Gbps data link; it's more like 10 Mbps. It's hard to get the phone company to install a fiber cable run up a mountain.
Our VLBI data are stored on hard disks at a rate of ~1 Gbps, then correlated later on some big computer back east. We have to wait days to learn if interference fringes were detected!
The magnetic domains and track widths are on the order of 20 nanometers these days, so considering that the average molecule is a nanometer or two in diameter, disks will have to use some other method of storage to get beyond a petabyte per drive.
That video of the leaking pipe shows stuff coming out of it at a rate of about two pipe diameters per second, if you just watch how fast the moving stuff moves. Some simple math puts that flow rate, for the 20 inch diameter pipe that it's said to be, at 80,000 bbl/day.
The math: the pipe area is ~2 sq ft, the flow rate is ~3 ft/second, the volume per second is 6 cu ft, which is about 45 gallons or one barrel per second. That's ~80k bbl/day.
If my math is wrong, please show me how it's wrong. It's the same math that the univ professors are using.
telling all of us how much we should appreciate our fine new immigration law.
So buy a Prius. It has the same mechanism in it. The two drive sources are the gasoline engine and a motor-generator MG1. See an animation of it here: http://eahart.com/prius/psd/
Not just that, but they are visually interesting plot tools. Real computer use is too visually dull to be used in a Hollywood movie. And the text on the screen is much to small to resolve when the movie is shown on TV, so Hollywood makes the words really big. Maybe that will change when Blu-Ray becomes standard.
The payload is the expensive part. The folks in the office next to mine are building a similar telescope for TeraHertz observations. The screws don't cost $150 each as an earlier commenter suggested, but the TeraHertz components are rather pricey, since the small market for that stuff results in one-digit serial numbers. And it uses liquid helium to cool the receiver. And they aren't building it sturdily enough to handle being dragged across parked cars! (They may change their design after watching the video...)
Actually, he's not evil at all. He's just into bigger engines than I am. http://www.selectric.org/ vs http://www.cathodecorner.com/
Our homebrew machine could play chess, play Star Trek, act as a word processor (my mom typed her thesis on it), we played 3D stereo Space War on an oscilloscope dot display, etc. It could do amazing things, all in 4K of RAM and a homemade 32x16 character display.
You think you had it hard waiting for paper tape? My brother wrote his own 2K Tiny Basic interpreter for the M6800 from scratch, stored on reel-to-reel tape. We wanted a printer; Dad brought home a Friden Flexowriter and invited us to make it talk. We did. We were lazy enough to ask for a 4K RAM kit with a genuine PC board for Christmas, since wire-wrapping 32 chips was a bit tedious.
The Altair really got the hobby computer market going. It was by no means perfect, but it was something that a lot of people were hungry for. I had the thrill of working in a retail computer store in 1978 when the IMSAI and Apple were going head-to-head. [IMSAI is a spelling error in this text entry box, which tells you who won.]
It's a lot of fun.
Notice that sometimes the columns of type gaps between them or are run together. This printer wasn't nearly as well made as the American behemoths of the sixties.
Noise is proportional to the square root of bandwidth. The signal-to-noise ratio determines the bandwidth of the signal that can be demodulated. So if they're transmitting a 1Mbps modulation scheme, then the bandwidth would be several tens of kHz and carrier has to be strong enough to present a reasonably noise-free signal of those tens of kHz bandwidth to the demodulator.
On the other hand, if it's a 3bps modulation scheme, then the carrier could be nearly invisible and still have the necessary S/N to present a useful signal to the demodulator, since the receiver bandwidth can be reduced to under 1 Hz.
So unless you know the modulation bandwidth, it's impossible to say how much carrier you need to recover the modulation.
Whether the carrier is strong enough depends on the bandwidth of the signal. The downlink apparently (Google is being stubborn) uses phase shift keying at a selectable data rate from a few bps to a couple hundred kpbs, depending on conditions.
So you'd have to have a suitable demodulator to get the data, and the big message given by the fine article is that you'd need a much bigger dish to get enough S/N to have anything to demodulate.
I work on radio telescopes, not deep space monitors, so I don't know squat about the demodulation.
At 3500m altitude, even tying your shoelaces is tricky.