Rather quiet?
According to your numbers: -6dB per doubling of distance.
500 ft = 152m
8*2*2*2*2=128m
four doubling of distance equals 4*6=24dB
The flying car will give approximatly 89 dBA at 8m! And the sound will travel longer, as it is up in the air and is less attenuated by building etc. (Hot air ballons are heard for quite a distance!)
The problem is in measuring what is an unused channel. A good example is the communication with the mars rovers. It takes something like a 70 m dish and a very very good reciever to be able to listen to them. That makes it probable that your broadband network card will assume that the channel is free, and begin to use it, and thus effectivly kill the reception from mars.
Some kind of frequency allocation scheme will always be needed! Parts of the band could be allocated to agile radios, but you can not really remove the FCC.
You are kidding, right?
You know, ther is this nice thing called decimals. So the temperature goes from 0.5 degreed Celcius to 4.5 degrees Celsius. With a resolution of half a degree, which is standard, you get 200 steps from ice to boiling. But that comparison is meaningless, as you could just as easily add resolution to the Fahrenheit scale.
But not Zuse... But I shouldn't be surprised, one is American, the other German.
Hall of XXX is always interesting read when they are made in the US, one finds out much one didn't know... Things are sometimes invented a couple of years later than they were used in europe.:-)
It's like when one visits Houston Space Center: everything is "Worlds first" (if it was american), otherwise it is "Americas first". Soviet achievments does not exsist. I almost began to laugh at it when I ws there...
(Yes, I know I will get a "flamebait" for this...)
Yes, you can test a theory by making a prediction with it and see if it fits the outcome of an experiment. If it does not, then there is soemthing wrong with the theory. If it does, then we keep the theory. (That is the idealised idea, at least.)
But you can not disprove the existense of something. It is not possible. You can only prove the existence of something.
Taking your idea of a test "It's possible - all you have to do is show that the existance of extraterrestrial travel is a self-contradicting notion.". That would be a valid test only under the circumstance that we regard our understanding of physics and the universe as complete. Which we do not. The test works in mathematics, which is a closed theoretical system. It does not work for physics. There is a lot of things that are possible within our understanding of physics/cscience, but that does not make them true. Examples would be the face on mars, still living Bigfoot in some jungle etc. Nothing really contradicts physics/biology there, but that does not make the theories "true", or probable.
But there is! At least in one restaurant in Copenhagen, and it has had the buttons for at least 20 years. Button placed on a lamp over the table, in the same way as in airplanes. (Never seen them used though, service was excellent.)
But the leakage will be a problem! If you are close to me, and I am far from the 10kW transmitter. Everybody on the low power side assumes that if you listen to a high-power station you are also close to it. On the contrary: stations transmit with high power in order to reach further, and a high power station will have more area on "the margin". Alas, more places where your low-power station may interfere or swamp the high-power station.
A phased array can also be electronically steerable - that is what makes them interesting (apart from being flatter then reflector antennas)
And if you have a way of determining the range to a transmitter by the recieved phase only - not triangulation, not amplitude, and manage to get around the phase-rotation ambiguitues, it would be very interesting to see it... (Especially if you manage in an incohorent system...)
In large I agree, but:
-I don't think they are less noisy, instead a highfrequency source is needed to generate the plasma, which makes noise.
-They are not necessarily lighter, the glass tube needed to contain the plasma weighs easily more than a corresponfing thin wire.
But you can turn them off and make them invisible to radar, which may be a good thing.
(The claims of fast beamsteering has no merit until they show in what way they are faster than an array antenna.) And plasma technology does not make the antennas smaller. Maxwell does still apply.
In the conclusions of the article they state that: "If standard, off-the-shelf wireless hardware is capable of performing these same tasks and why is it so expensive?"
-Probably because they didnt achieve air-to-ground communication. They only achieved communication between two objects moving in parallel at the same speed, which is equal to communication between two stationary objects. RF communication standards are made to operate up to a certain speed, which range from "walking" (for Bluetooth) to "highway" (for GSM). If the speed is larger the doppler-shift may disrupt the radio link. And when we are talking of commercial airlines the speeds are rather large, which demands that this is taken into account when designing the system specs.
(And yes, WLAN has been shown to operate at high speeds, eg. Porshe at full throttle, but I dont remember if it were a standard system.)
Because listening to "Beastie Boys" might disturb something, and they don't like to take chances. (Especially not in the US, where you might get sued for the worth of the company.)
And things are a little bit more critical when taking off or landing. Lets say that something made the plane pitch five degrees for a second. At 10.000 feet it does not matter much, but at 10 ft it is the same as disaster.
It is probably not possible to walk unassisted, but with assitance or support you can walk by having the legs perform automatic routines. (A little bit like toy robots.)
The people behind the Bion project have discussed this application.
And how much energy is needed to keep something suspended above the floor?
(Hint: how much current does an ordinary piece of string draw.)
Elementary physics, again. Keep your force, energy, power and work apart!
And this explains that the energy comes from??? It explains nothing - I thought/. was above this...
Re:Wireless by nature divides bus time
on
USB Going Wireless
·
· Score: 1
But you can divide the bandwidth in the frequency domain instead of in the time domain, giving each client a continous bit stream but at a lower bitrate.
If memory serves me, they have a range of 30-75 meters/day, after the recent sofware upgrade. Which would give a maximum distance of over 11km, given that they dont find anything interesting on they way and starts investigating it.
Oh yes, they are. A lot of people are. It is something of a holy grail: to have something onto which skin will attach itself. But nobody has succeded yet.
So wireless transmission is the safe route to go.
(And then we dont want to discuss that the scarring cited in the parent occurs inside the brain... How safe that is nobody knows...)
Very annoying!
-If the linked words are marked by another colour or underlined. A well trained reader has a few fixations of the eye on each row of text. But these markings would not be seen as standard text, and will thus generate more fixations and a "stuttered" reading experience.
-Trying to read a wiki text with a lot of references illustrates this point: It is OK if the text is short, but a longer text is virtually unreadable.
Maybe because most of the competitors were attracted to the computational problems and not the mechanical, and thus underestimated the latter?
And even if you now that the machanical side is what will take you to the finish line, it is still not easy. Just look at the Paris-Dakhar race: a lot of mechanical breakdowns with human drivers each year.
Slashdot Mirror
Rather quiet? According to your numbers: -6dB per doubling of distance.
500 ft = 152m
8*2*2*2*2=128m
four doubling of distance equals 4*6=24dB
The flying car will give approximatly 89 dBA at 8m! And the sound will travel longer, as it is up in the air and is less attenuated by building etc. (Hot air ballons are heard for quite a distance!)
The problem is in measuring what is an unused channel. A good example is the communication with the mars rovers. It takes something like a 70 m dish and a very very good reciever to be able to listen to them. That makes it probable that your broadband network card will assume that the channel is free, and begin to use it, and thus effectivly kill the reception from mars.
Some kind of frequency allocation scheme will always be needed! Parts of the band could be allocated to agile radios, but you can not really remove the FCC.
This is very very wrong. The amount of data is set by Shannon, as described above, and is linear with bandwidth.
Shannons law is that the maximum Capacity C is
C=B*log(1 + S/N)
You are kidding, right?
You know, ther is this nice thing called decimals. So the temperature goes from 0.5 degreed Celcius to 4.5 degrees Celsius. With a resolution of half a degree, which is standard, you get 200 steps from ice to boiling. But that comparison is meaningless, as you could just as easily add resolution to the Fahrenheit scale.
The Visby ship has tried to minimize its thermal signature, cf. the exhaust is piped into the sea below the surface.
If you think real hard you can probably see a solution to that...
And that reminds me, Sweden also has a radar system that is able to detect stealth ariplanes, same principle.
But not Zuse... But I shouldn't be surprised, one is American, the other German.
:-)
Hall of XXX is always interesting read when they are made in the US, one finds out much one didn't know... Things are sometimes invented a couple of years later than they were used in europe.
It's like when one visits Houston Space Center: everything is "Worlds first" (if it was american), otherwise it is "Americas first". Soviet achievments does not exsist. I almost began to laugh at it when I ws there...
(Yes, I know I will get a "flamebait" for this...)
Please learn some scientific theory.
Yes, you can test a theory by making a prediction with it and see if it fits the outcome of an experiment. If it does not, then there is soemthing wrong with the theory. If it does, then we keep the theory. (That is the idealised idea, at least.)
But you can not disprove the existense of something. It is not possible. You can only prove the existence of something.
Taking your idea of a test "It's possible - all you have to do is show that the existance of extraterrestrial travel is a self-contradicting notion.". That would be a valid test only under the circumstance that we regard our understanding of physics and the universe as complete. Which we do not. The test works in mathematics, which is a closed theoretical system. It does not work for physics. There is a lot of things that are possible within our understanding of physics/cscience, but that does not make them true. Examples would be the face on mars, still living Bigfoot in some jungle etc. Nothing really contradicts physics/biology there, but that does not make the theories "true", or probable.
With todays technology, what wouldn't?
But there is! At least in one restaurant in Copenhagen, and it has had the buttons for at least 20 years. Button placed on a lamp over the table, in the same way as in airplanes. (Never seen them used though, service was excellent.)
But the leakage will be a problem! If you are close to me, and I am far from the 10kW transmitter.
Everybody on the low power side assumes that if you listen to a high-power station you are also close to it. On the contrary: stations transmit with high power in order to reach further, and a high power station will have more area on "the margin". Alas, more places where your low-power station may interfere or swamp the high-power station.
A phased array can also be electronically steerable - that is what makes them interesting (apart from being flatter then reflector antennas)
And if you have a way of determining the range to a transmitter by the recieved phase only - not triangulation, not amplitude, and manage to get around the phase-rotation ambiguitues, it would be very interesting to see it... (Especially if you manage in an incohorent system...)
In large I agree, but:
-I don't think they are less noisy, instead a highfrequency source is needed to generate the plasma, which makes noise.
-They are not necessarily lighter, the glass tube needed to contain the plasma weighs easily more than a corresponfing thin wire.
But you can turn them off and make them invisible to radar, which may be a good thing.
(The claims of fast beamsteering has no merit until they show in what way they are faster than an array antenna.) And plasma technology does not make the antennas smaller. Maxwell does still apply.
In the conclusions of the article they state that: "If standard, off-the-shelf wireless hardware is capable of performing these same tasks and why is it so expensive?"
-Probably because they didnt achieve air-to-ground communication. They only achieved communication between two objects moving in parallel at the same speed, which is equal to communication between two stationary objects. RF communication standards are made to operate up to a certain speed, which range from "walking" (for Bluetooth) to "highway" (for GSM). If the speed is larger the doppler-shift may disrupt the radio link. And when we are talking of commercial airlines the speeds are rather large, which demands that this is taken into account when designing the system specs.
(And yes, WLAN has been shown to operate at high speeds, eg. Porshe at full throttle, but I dont remember if it were a standard system.)
Because listening to "Beastie Boys" might disturb something, and they don't like to take chances. (Especially not in the US, where you might get sued for the worth of the company.)
And things are a little bit more critical when taking off or landing. Lets say that something made the plane pitch five degrees for a second. At 10.000 feet it does not matter much, but at 10 ft it is the same as disaster.
It is probably not possible to walk unassisted, but with assitance or support you can walk by having the legs perform automatic routines. (A little bit like toy robots.)
The people behind the Bion project have discussed this application.
And how much energy is needed to keep something suspended above the floor?
(Hint: how much current does an ordinary piece of string draw.)
Elementary physics, again. Keep your force, energy, power and work apart!
And this explains that the energy comes from??? It explains nothing - I thought /. was above this...
But you can divide the bandwidth in the frequency domain instead of in the time domain, giving each client a continous bit stream but at a lower bitrate.
If memory serves me, they have a range of 30-75 meters /day, after the recent sofware upgrade. Which would give a maximum distance of over 11km, given that they dont find anything interesting on they way and starts investigating it.
Oh yes, they are. A lot of people are. It is something of a holy grail: to have something onto which skin will attach itself. But nobody has succeded yet.
/Jott
So wireless transmission is the safe route to go. (And then we dont want to discuss that the scarring cited in the parent occurs inside the brain... How safe that is nobody knows...)
Very annoying!
-If the linked words are marked by another colour or underlined. A well trained reader has a few fixations of the eye on each row of text. But these markings would not be seen as standard text, and will thus generate more fixations and a "stuttered" reading experience.
-Trying to read a wiki text with a lot of references illustrates this point: It is OK if the text is short, but a longer text is virtually unreadable.
Maybe because most of the competitors were attracted to the computational problems and not the mechanical, and thus underestimated the latter? And even if you now that the machanical side is what will take you to the finish line, it is still not easy. Just look at the Paris-Dakhar race: a lot of mechanical breakdowns with human drivers each year.