What limits throughput on a wireless connection? Is it broadcast power, frequency, amount of spectrum, or "c"?
All of the above!
The most limiting factor is the amount of spectrum -- the bandwidth allocated to the signal. If you're restricted to a very narrow set of frequencies, you can't send as much data in a given amount of time.
But, once you've picked the bandwidth to use, broadcast power and frequency each affect how well the transmitted signal can be received. Lower frequencies pass through solid objects more easily, for example, but often require more broadcast power. There are myriad details affecting the quality of a signal as it passes from the transmitter to the receiver, not the least of which is interference from other transmitters.
And finally, "c" ultimately affects the latency of your signals. NASA's conversations with the Voyager spacecraft would be an extreme example: it takes about 25 hours now for a signal to make a round trip from Earth to Voyager 1 and back. Closer to home, even Earth satellites are far enough away that the speed of light becomes a limitation -- the round trip to a geosynchronous satellite is 0.239 seconds. If your signal is mostly one-way, this has very little impact. Television, for example, isn't hindered by this. But any kind of interactive connection like online gaming or even telephone conversations are adversely affected by that amount of latency.
I still think that the emerging spread spectrum technologies are our best bet for wireless computer networking.
This is just like arguing that two stereo systems in the same room "interfere" with each other.
Have these people forgotten that certain 2.4GHz cordless phones completely blast 802.11 devices off the air?
I, for one, would like to see a system that uses the entire spectrum to allow upwards of 1000Mbps throughput. There are certain places where there'd be an application for that use of the spectrum.
Isn't the Governor-elect of Caleeforneea planning to send a mission to Mars? Something about turning on the big hidden alien generator to unfreeze the buried atmosphere?
I could swear I saw him talk about that on TV... I totally can't recall exactly where.
Just by listening to the previews of songs that I've purchased I can say that the purchased tracks sound WAY better than the previews. I don't know where the difference lies but the previews are definitely lower quality than the purchased tracks.
That makes no sense though:
In his introduction speech, Steve Jobs explicitly said that the previews were full quality.
Network monitoring tools show that a 30 second preview downloads about 700kB, which agrees with a 128kbps data rate plus overhead, the same rate as the purchased files.
I even used Audio Hijack to record the preview and the same 30 seconds from the purchased track so I could play them back and forth. Even with headphones, I could not discern a difference.
I'm curious what's causing you to be getting substandard previews. Are you using Mac OS or Windows? Have you tried checking the "load complete preview before playing" box in iTunes preferences?
The word "limb" in this sense comes from latin limbus, "border." Its meanings in English all have to do with the edge of a round object.
Oddly enough, the more common meaning of limb is actually a different word, spelled "lim" in Old English. This etymology page says that the "b" appeared in the 16th century for no apparent reason, though American Heritage says that it was probably picked up from the other "limb."
So unlike other separate words pronounced alike, such as everyone's favorite their/there pair, limb and lim wound up being spelled the same by someone's mistake.
It's wierd that people so vehemently defend correct spellings, given that so many of them originated as mistakes some time in the past.
I can't get a copy now and can ignore it until the FTC gets it available again
Except that it it is available at donotcall.gov. I don't think the list was unavailable for very long -- what with congress ammending the law so quickly and all to reaffirm their intent that the FTC administer the list.:)
You get an "A" if you can explain how a see-saw is equivilant to an electrical transformer
Here's an attempt:
Consider a see-saw with one side twice as long as the other, measured from the fulcrum. The load on the short end of the see-saw is twice as massive as the load on the long end, and the see-saw balances. Motion of either load causes the other to move, such that the lighter mass moves twice as far as the heavy one.
The analogy, I believe, is that the mass of the loads would be the electric pressure, or voltage. The distance moved would be the amount of electric current, or amperage. The long side of the see-saw has half as many transformer windings as the other side, and thus a large current of small voltage on that side induces a smaller current of a larger voltage on the other side.
Or maybe that analogy sucks, and it would make more sense intuitively if you used mass=current, height=voltage? Then the long side would be the more-windings side.
But the basic idea is right, yes?
I am not familiar, though, with "coupled transducers" and domains... can you explain?
Outdoors on a private campus. Still Microsoft's property. Just because you can see the sky doesn't mean that you're somewhere "public"!
No, I don't think it's any embarassment at all on Microsoft's part. Secrecy is so important in the technology business that the very act of taking and posting pictures needs to be dealt with seriously.
I rather suspect that Apple would deal with this just as harshly, if not even more so, given the history of leaks about future products coming out of the Apple campus.
1. Hostility toward or prejudice against Jews or Judaism. 2. Discrimination against Jews.
Words' meanings aren't always derived from a literal interpretation of their parts.
That said, I completely agree with your point that unfounded accusations of anti-semitism are terribly inappropriate. One can disagree with, nay even hate the government of Israel without harboring any anti-semitism at all.
(Likewise, one should be able to hate the current administration of the US without being labeled anti-patriotic or an "evildoer" there.)
Of course, that's no fun -- it's much easier just to box people into little labels.
So, the resulting aurora should be on par with the 1989 event.
Actually, we won't know if this flare and CME will cause auroras or not. If the magentic field associated with this flare is in the same direction as the Earth's, the high energy particles are largely deflected away from and past us, with no pretty light show.:(
But if the magnetic field is opposite to ours, then the solar wind can be funnelled directly into our upper atmosphere. I don't think there's any good predictor -- we just have to wait for it to get here.
were not shielded properly and actually can panic when substantial CME's like this occur.
Not unless you're flying those servers on high-altitude aircraft or in orbit.
High energy solar radiation is well absorbed by our atmosphere here on Earth. This is why many of our solar observations must be taken from space. We and our computers are quite safe.
The only terrestrial effects from CMEs and the like come about because of perturbations to our magnetic field -- a change to the magnetic field can induce currents in power lines, overloading equipment connected to them.
Your random computer crashes are a complete coincidence.
After having been a regular/. reader and poster, the site will randomly grant you 5 moderator points every once in a while. Those points must be used within a few days before they expire.
My experience is that/. knows when I'm about to go out of town without internet access, and gives me my mod points right before I leave. The sound of the slash code giggling is one of the erriest sounds in the universe.
"Also, at around 100Mbps read and write to disk, it is faster than our SCSI system which has an I/O of 50Mbps"
Never mind the whole base-2/base-10 "mebibyte" business... why can't people learn that the case of the "b"/"B" is significant!? Clearly he meant megaBytes, not bits.
By the way, Apple advertises the Xserve RAID's throughput in excess of 200MBps.
The brain has 100 billion neurons, but most of it goes for the cerebellum (70 billion), what is basically a fine movement, motor co-processor.
Keep in mind, though, that your "knowledge" of how to ride a bicycle resides in the cerebellum. Amazingly enough, some of the conditioning for repetitive movement is stored by the nerve cells in the brain stem and the spinal cord itself, as well.
I can see how the glitter pen would have added to the humor a bit.:)
- Peter
-- Years ago, my mother used to say to me, "In this world, Elwood, you must be oh so smart, or oh so pleasant." Well, for years I was smart. I recommend pleasant. You may quote me. - Slashdot User 16933
Slashdot Mirror
Please learn how to make a link, rather than subject /. to another spaced-out URL!
Here's the Space.com article.
- Peter
What limits throughput on a wireless connection? Is it broadcast power, frequency, amount of spectrum, or "c"?
All of the above!
The most limiting factor is the amount of spectrum -- the bandwidth allocated to the signal. If you're restricted to a very narrow set of frequencies, you can't send as much data in a given amount of time.
But, once you've picked the bandwidth to use, broadcast power and frequency each affect how well the transmitted signal can be received. Lower frequencies pass through solid objects more easily, for example, but often require more broadcast power. There are myriad details affecting the quality of a signal as it passes from the transmitter to the receiver, not the least of which is interference from other transmitters.
And finally, "c" ultimately affects the latency of your signals. NASA's conversations with the Voyager spacecraft would be an extreme example: it takes about 25 hours now for a signal to make a round trip from Earth to Voyager 1 and back. Closer to home, even Earth satellites are far enough away that the speed of light becomes a limitation -- the round trip to a geosynchronous satellite is 0.239 seconds. If your signal is mostly one-way, this has very little impact. Television, for example, isn't hindered by this. But any kind of interactive connection like online gaming or even telephone conversations are adversely affected by that amount of latency.
I still think that the emerging spread spectrum technologies are our best bet for wireless computer networking.
- Peter
Exactly!
This is just like arguing that two stereo systems in the same room "interfere" with each other.
Have these people forgotten that certain 2.4GHz cordless phones completely blast 802.11 devices off the air?
I, for one, would like to see a system that uses the entire spectrum to allow upwards of 1000Mbps throughput. There are certain places where there'd be an application for that use of the spectrum.
- Peter
Isn't the Governor-elect of Caleeforneea planning to send a mission to Mars? Something about turning on the big hidden alien generator to unfreeze the buried atmosphere?
I could swear I saw him talk about that on TV... I totally can't recall exactly where.
- Peter
I apologise for my horrible spelling, it's 2 AM
2 AM? For most true geeks, that's like mid-afternoon.
- Peter
Just by listening to the previews of songs that I've purchased I can say that the purchased tracks sound WAY better than the previews. I don't know where the difference lies but the previews are definitely lower quality than the purchased tracks.
That makes no sense though:
In his introduction speech, Steve Jobs explicitly said that the previews were full quality.
Network monitoring tools show that a 30 second preview downloads about 700kB, which agrees with a 128kbps data rate plus overhead, the same rate as the purchased files.
I even used Audio Hijack to record the preview and the same 30 seconds from the purchased track so I could play them back and forth. Even with headphones, I could not discern a difference.
I'm curious what's causing you to be getting substandard previews. Are you using Mac OS or Windows? Have you tried checking the "load complete preview before playing" box in iTunes preferences?
- Peter
The word "limb" in this sense comes from latin limbus, "border." Its meanings in English all have to do with the edge of a round object.
Oddly enough, the more common meaning of limb is actually a different word, spelled "lim" in Old English. This etymology page says that the "b" appeared in the 16th century for no apparent reason, though American Heritage says that it was probably picked up from the other "limb."
So unlike other separate words pronounced alike, such as everyone's favorite their/there pair, limb and lim wound up being spelled the same by someone's mistake.
It's wierd that people so vehemently defend correct spellings, given that so many of them originated as mistakes some time in the past.
- Peter
The previews are downsampled tremendously.
No, the previews are the same datarate as the purchased files. No difference at all.
- Peter
I can't get a copy now and can ignore it until the FTC gets it available again
:)
Except that it it is available at donotcall.gov. I don't think the list was unavailable for very long -- what with congress ammending the law so quickly and all to reaffirm their intent that the FTC administer the list.
So, sign on up and download your copy!
- Peter
You get an "A" if you can explain how a see-saw is equivilant to an electrical transformer
Here's an attempt:
Consider a see-saw with one side twice as long as the other, measured from the fulcrum. The load on the short end of the see-saw is twice as massive as the load on the long end, and the see-saw balances. Motion of either load causes the other to move, such that the lighter mass moves twice as far as the heavy one.
The analogy, I believe, is that the mass of the loads would be the electric pressure, or voltage. The distance moved would be the amount of electric current, or amperage. The long side of the see-saw has half as many transformer windings as the other side, and thus a large current of small voltage on that side induces a smaller current of a larger voltage on the other side.
Or maybe that analogy sucks, and it would make more sense intuitively if you used mass=current, height=voltage? Then the long side would be the more-windings side.
But the basic idea is right, yes?
I am not familiar, though, with "coupled transducers" and domains... can you explain?
- Peter
Yeah, if you want to pay for the download
Huh? They have it for free, in both streaming or downloadable real audio.
- Peter
PLEASE! Don't bother us with facts. They complicate things needlessly.
- Peter
The other possibility might be for /. editors to... well, actually READ slashdot.
Nah.
- Peter
What, they don't own the land their buildings are on?
- Peter
I'm sure some of us here would recognize this pattern:
.xx.x.xx
xx....xx
x.x...xx
x..x..xx
xx..xx..
xxxxx.x.
- Peter
The photo was taken outdoors
Outdoors on a private campus. Still Microsoft's property. Just because you can see the sky doesn't mean that you're somewhere "public"!
No, I don't think it's any embarassment at all on Microsoft's part. Secrecy is so important in the technology business that the very act of taking and posting pictures needs to be dealt with seriously.
I rather suspect that Apple would deal with this just as harshly, if not even more so, given the history of leaks about future products coming out of the Apple campus.
- Peter
Here's a clue for free: Palestinians are Semites
Oooh! Free clues being given out! Sign me up! Just make the clues accurate, please:
Anti-semitism is an English word that means:
1. Hostility toward or prejudice against Jews or Judaism. 2. Discrimination against Jews.
Words' meanings aren't always derived from a literal interpretation of their parts.
That said, I completely agree with your point that unfounded accusations of anti-semitism are terribly inappropriate. One can disagree with, nay even hate the government of Israel without harboring any anti-semitism at all.
(Likewise, one should be able to hate the current administration of the US without being labeled anti-patriotic or an "evildoer" there.)
Of course, that's no fun -- it's much easier just to box people into little labels.
- Peter
So, the resulting aurora should be on par with the 1989 event.
:(
Actually, we won't know if this flare and CME will cause auroras or not. If the magentic field associated with this flare is in the same direction as the Earth's, the high energy particles are largely deflected away from and past us, with no pretty light show.
But if the magnetic field is opposite to ours, then the solar wind can be funnelled directly into our upper atmosphere. I don't think there's any good predictor -- we just have to wait for it to get here.
- Peter
were not shielded properly and actually can panic when substantial CME's like this occur.
Not unless you're flying those servers on high-altitude aircraft or in orbit.
High energy solar radiation is well absorbed by our atmosphere here on Earth. This is why many of our solar observations must be taken from space. We and our computers are quite safe.
The only terrestrial effects from CMEs and the like come about because of perturbations to our magnetic field -- a change to the magnetic field can induce currents in power lines, overloading equipment connected to them.
Your random computer crashes are a complete coincidence.
- Peter
embedding spyware into their application. That's the widespread rumor
Um... would you care to substantiate that "rumor"? Repeating a rumor doesn't make it true.
- Peter
By the way, how do you mod posts anyways?
/. reader and poster, the site will randomly grant you 5 moderator points every once in a while. Those points must be used within a few days before they expire.
/. knows when I'm about to go out of town without internet access, and gives me my mod points right before I leave. The sound of the slash code giggling is one of the erriest sounds in the universe.
Check out the FAQ...
After having been a regular
My experience is that
- Peter
or you could spend your $50 worth of cold hard cash on pepsi and get the tunes that way.
You'd have to buy $150 worth of pepsi, since only 1/3 of the caps are winners.
- Peter
The linked article quotes the tech center's director:
"Also, at around 100Mbps read and write to disk, it is faster than our SCSI system which has an I/O of 50Mbps"
Never mind the whole base-2/base-10 "mebibyte" business... why can't people learn that the case of the "b"/"B" is significant!? Clearly he meant megaBytes, not bits.
By the way, Apple advertises the Xserve RAID's throughput in excess of 200MBps.
- Peter
The brain has 100 billion neurons, but most of it goes for the cerebellum (70 billion), what is basically a fine movement, motor co-processor.
Keep in mind, though, that your "knowledge" of how to ride a bicycle resides in the cerebellum. Amazingly enough, some of the conditioning for repetitive movement is stored by the nerve cells in the brain stem and the spinal cord itself, as well.
- Peter
I can see how the glitter pen would have added to the humor a bit. :)
- Peter
--
Years ago, my mother used to say to me, "In this world, Elwood, you must be oh so smart, or oh so pleasant." Well, for years I was smart. I recommend pleasant. You may quote me. - Slashdot User 16933