It's just cheap components. The humming is extremely low frequency compared with the RF. Think 60 Hz vs 2400 MHz. There's nothing dangerous here, although I agree this is really annoying. You'll find it in lots of other electronics too.
Since your hardware isn't as flexible as it could be, you can't get away with tricks like special channels and using inbetween spectrum.
So with standard equipment and standard frequencies: 1) Use 802.11n, 5 GHz if possible (less crowded) 2) Try the wider modes (HT40) to see if they can hop around your interference better (just force it and see what happens) 3) Put metal bug screen around the back of your posters and such, (with your AP not behind them). This will decrease sensitivity to whatever is behind your bords but it will not help with anything infront of them. 4) Turn your beacon interval way down, so that if a device does loose signal it will find it relatively quickly. 5) More power for your AP will help, directional antennas are good *if* you know you're only going to be in a specific area (usually, at least a hemispherical panel works) 6) follow good RF practices (don't put antennas against other objects, for example) 7) operate multiple APs at once with the same SSID -- may help, might not too, depends on how bad your interference is. And how intelligent your wifi clients are. Some won't jump AP until the signal is almost uselessly low.
If you can pick up the undesired signal stronger in one antenna, and the desired signal stronger in the other, and I understand you'll get both stations in both antennas, that's ok, then you can combine the signals together. The matching network will achieve the right impedance, and ideally have an adjustment for phase so that you can adjust it and get the most rejection.
You are correct to focus on the antenna and RF-side of things.
One obvious option is to move your headend to a better location -- but that's obviously costly and you've already considered it.
What I would do is, in addition to using the most narrow, highest front-to-back (and ideally front-to-side) ratio antenna to pick up the station you want, is also use one to pick up the station you DON'T want. You can then build a matching network that subtracts the undesired signal. It's a little complicated, and you might even need to put each through IF mixing first, but a good engineer can pull this off. You're essentially actively rejecting what you don't desire.
Depending on the directionality of the unwanted station in respect to the wanted signal, you may also be able to use phasing to your advantage -- if you can get the bad signal to arrive out of phase in two antennas, but the desired signal in-phase, then a very simple combiner will take care of it.
So to be fluent, a high-school student must know about 2,000 characters?!
I'm a Chinese minor (in the US at a university), and we only learn the most basic of topics (sports, food, family, transportation). My list of "you better know these" is about 5,000 characters long. And I use traditional characters too, because I prefer a 1:1 mapping of meaning to character.
So a 10% increase shouldn't be a big deal if you're already (somewhat) used to writing them out.
As a current ECE undergrad, I have a few things to say.
Yes, power point (and other computer technologies) are very useful for specific tasks, such as presenting videos, showing complicated graphs, and long code listings.
But when it comes to learning and understanding, and especially learning the theory behind a method, watching the professor work it out with chalk (or markers, whatever) is immensely more valuable than seeing the results print, phrase-by-phrase, on a screen.
Add this to the fact that power point presenters typically dim the lights, mumble the words on the screen, and typically have a 5-minute overhead time spent "playing with the computer" trying to find their files, figure out why the font is wrong, etc.
Many have pointed out that it comes down to the quality of the teacher. And this is true. But to link causality to cause, if the teacher relies too heavily on powerpoint, they probably suck at teaching with any method.
Learning from a all powerpoint lecture is sort of like learning from a set of flashcards. Are they really that different? Except for animations or mulit-page code listings, they're about the same, and equally "useful".
Some have pointed out that powerpoint is great if you want to download the notes on your own time. This is true, but going to class and taking your own notes is much more useful. If your notes aren't clear, or you missed class that day, then ask a friend for a copy of the notes. It's that simple, and part of normal "group studying" anyway. Heck, you could even read the text book, do the homework, and go to office hours in the worst case...
Good point -- for closed-source applications, your system has to closely match whatever a particular piece of software was written to run under.
They have some kind of solution for PPC linux, I can't remember what it is though. I think it's a third-party somewhat compatible plugin.
But I think the real desktop linux barrier is the lack of a standard desktop environment. Last time I toyed with desktop linux, just about everything was half-way broken (compared with my mac, that is). Changing around screen resolutions, for example, involved authenticating as root, hoping I chose a valid resolution, and restarting the X Window system. Dragging a file from a web browser to the desktop -- make a link? save the file? How about dragging an mp3 from xmms to an email. Not likely to work. Oh, and cut/copy/paste... don't get me started!
Linux is a great server environment, and also a good graphical environment for specific non-general purposes, but I think it has a very long way to go before it's a real desktop os alternative.
So until they work all this and more out, I'm sticking with Mac OS X... unix, graphics, multimedia, and industry support... good stuff imo:)
The reason your post is "invalidated" is that you seem to suggest that if the kernel could emulate x86 instruction execution, then the article's author's problems would be solved.
Yet it's obvious, with modern linux distributions, you don't need to worry about if a program is already compiled for intel. You have bigger problems, like the graphics on the ps3, or how the os organizes its libraries, etc.
>Would it be too slow to load a slim PPC kernel and replace init >with an optimized PPC-compiled qemu instance (basically; it >would require much more than this) and run a virtual x86 >machine on that?
I mean, why? Why would any linux user need compatibility with another chip? To run linux apps compiled for the other chip? You've got to be kidding.
To run wine? And then run windows? Windows what? 3.11? Nothing modern will run well in this crazy proposed setup. The cell processors will indeed "deal with it" but in the years you would spend doing this, you won't accomplish anything useful when you're done.
And so that's why the parent poster "invalidated" your post.
>Since the PS3's Cell Processor is PowerPC based, you won't be >able to use any Linux software that's compiled for x86, which is, >unfortunately, most of it.
I have to say, to most linux users, the specific architecture and processor really aren't meaningful. The linux kernel, gnu userland, and associated popular applications have always been distributed in source code first, and binaries as they are made available. The entire concept of open-source depends on source distribtion.
It is absolutely no problem if an app is distributed in source form or binary (compiled). True, a "standard" linux install base, while it may be defined, is rarely realized. So you could argue that distributing in source code creates problems because needed dependencies can't always be met. But then again, this doesn't help with binary distribution either. Ever try to install an RPM on a non-rpm-ish linux distro? It can be done, yes, but it involves a lot of details. Just as compiling does.
Debian is awesome for distributing such a wide range of apps compiled for so many architectures. But it is truly sad to see someone write that it is "unfortunate" that most linux installs are x86 and his is ppc. The entire concept of linux is that linux is a kernel and a userland distributed in source. It doesn't matter what hardware you have (within reasonable limits... toasters, watches, etc).
There's nothing "unfortunate" about an intel chip, a sparc processor, or a power pc, in terms of the ability of linux to run on it. It's a bigger deal if you're running generic pc hardware with some new video or wifi card. But even this sort of par for the course these days.
I bought a sun box at goodwill once and besides an intact customer database for several large companies, it also had the admin's personal backup files, including his "My Documents" folder, his Palm cell phone, and 1200 dpi scans of his passport. Oh, and some file called "passwords.doc". No idea what is in there...
Maybe I'm not understanding your point, but it takes a LOT of energy to power an electric pizza oven. The small toaster oven at my house uses over 1000 watts. I'm sure a larger electric pizza ovens use a lot more. The $40 one at sears.com uses 950 watts.
This doesn't minimize her invention though -- I'm sure any kind off coal or wood-burning oven would work if you were careful.
Legally, your apartment complex MAY NOT prevent you from putting a "reasonable" size TV antenna up on the roof. You're allowed by law to do so. The law exists to prevent people from feeling "forced" to get cable instead of using OTA antenna.
Tell your apartment complex you'll buy the most reasonable antenna that does the job, and you'll also pay a qualified installer (unless they want to do it). If they say no, show them the law in the most kindest way possible.
Indoor antennas will never get you good results, especially at the bottom of a 3-story building.
There are actually standards for measuring receive strength. In the world of Amateur Radio, as well as commercial radio communications, we have something called the S-Unit. On some radios, these are displayed on an analog meter, and on some radios, they are displayed as "bars" on an LCD or with LEDs.
Basically, each division ("s unit") is ideally about 6dB different than the next, meaning a signal must double in strength twice to make a 1 s-unit difference. The top or near-top of the scale, called "S9" is typically calibrated at around 50 micro volts (at 50 ohms).
The point being, there is a standard for measuring signal with bars. Of course, manufactures don't always adhere to it. In the case of cell phones, who knows. But they probably could...
Wouldn't the GPS only tell your air seed? How would the GPS know if you were traveling at an incline? The Officer's radar gun measures the velocity on the road. The GPS probably compares your coordinates over a short time period and computes your velocity -- hardly accurate if you're traveling at an angle. Unless it's somehow able to factor this in as well. Anyone know?
There's nothing worse than watching a teacher "play computer" while you're trying to learn. It is a major distraction, and generally uses a lot more time than simply demonstrating a technique or example on a standard dry-erase or chalk board.
I once had a teacher who did everything with powerpoint and a wacom tablet. He never touched the chalk. And it was cool at first, because he had the ability to look things up on the internet, review his notes from the previous lecture, and even change his slides when he noticed mistakes.
But for me, I didn't learn much this way. Besides the fact that the lights were darkened (which made me sleepy), he would spend at least ten to fifteen minutes each day doing things like opening files and clicking on various dialog boxes. Had he simply used the three sliding chalkboards, very little time would have been wasted.
There isn't ANYTHING in physics, chemistry, or math that can't be represented fully on a chalkboard by a competent educator.
And I've had the old school teachers that abide by this notion. They really know their stuff. You think you need computer graphing software to demonstrate trig, calculus, or algebra? Previous generations got to the moon and back without much more than a slide rule and a 15-lb calculator. If you're an educator, and you find it more efficient to use mathlab or whatever instead of just drawing the darn thing, than please do kids a favor and step aside.
Even though you might be good at using the computer, if you can teach kids how to understand these concepts with nothing more than a piece of paper and a pencil, then you'll be lowering their reliance on graphing calculators and computers. Yes, these things are useful, sure, but when it comes to learning, better to learn the concept without the bells and whistles.
Just type 'say' and press return. Now type a phrase. Press return. You can now just type what you need to say and press return after each phrase, rather than typing 'say' each time.
The day I broke up with my x about 6 years ago, I decided to forget her phone number.
Besides not calling her, whenever I would think of the number, I diverted my thoughts to anything else.
Throughout the years, I would half-tempt myself to try and recall the number. Each time, I diverted the thought.
At this moment, if I try to remember the number, I have this feeling that the number is inside my head somewhere, but all those years of training have removed any possibility of recalling it.
I also think if I were to be given the first three digits, I would instantly recall the rest.
Anyone else here have interesting methods of forgetting or recalling?
Slashdot Mirror
It's just cheap components. The humming is extremely low frequency compared with the RF. Think 60 Hz vs 2400 MHz. There's nothing dangerous here, although I agree this is really annoying. You'll find it in lots of other electronics too.
You are in way over your head. If you accept this position with so little knowledge then you will get what you ask for.
You should consider sub-contracting this to someone with, say, a tiny dot of experience with: unix, wifi, and physical wires.
Yet another "do my job for me" slashdot post. Except, this is way too complex for an answer within a slashdot discussion.
Save yourself the trouble and back out while you can. Introduce someone else, get a commission on it, and be done with it.
Since your hardware isn't as flexible as it could be, you can't get away with tricks like special channels and using inbetween spectrum.
So with standard equipment and standard frequencies:
1) Use 802.11n, 5 GHz if possible (less crowded)
2) Try the wider modes (HT40) to see if they can hop around your interference better (just force it and see what happens)
3) Put metal bug screen around the back of your posters and such, (with your AP not behind them). This will decrease sensitivity to whatever is behind your bords but it will not help with anything infront of them.
4) Turn your beacon interval way down, so that if a device does loose signal it will find it relatively quickly.
5) More power for your AP will help, directional antennas are good *if* you know you're only going to be in a specific area (usually, at least a hemispherical panel works)
6) follow good RF practices (don't put antennas against other objects, for example)
7) operate multiple APs at once with the same SSID -- may help, might not too, depends on how bad your interference is. And how intelligent your wifi clients are. Some won't jump AP until the signal is almost uselessly low.
Hope that helps.
If you can pick up the undesired signal stronger in one antenna, and the desired signal stronger in the other, and I understand you'll get both stations in both antennas, that's ok, then you can combine the signals together. The matching network will achieve the right impedance, and ideally have an adjustment for phase so that you can adjust it and get the most rejection.
You are correct to focus on the antenna and RF-side of things.
One obvious option is to move your headend to a better location -- but that's obviously costly and you've already considered it.
What I would do is, in addition to using the most narrow, highest front-to-back (and ideally front-to-side) ratio antenna to pick up the station you want, is also use one to pick up the station you DON'T want. You can then build a matching network that subtracts the undesired signal. It's a little complicated, and you might even need to put each through IF mixing first, but a good engineer can pull this off. You're essentially actively rejecting what you don't desire.
Depending on the directionality of the unwanted station in respect to the wanted signal, you may also be able to use phasing to your advantage -- if you can get the bad signal to arrive out of phase in two antennas, but the desired signal in-phase, then a very simple combiner will take care of it.
So to be fluent, a high-school student must know about 2,000 characters?!
I'm a Chinese minor (in the US at a university), and we only learn the most basic of topics (sports, food, family, transportation). My list of "you better know these" is about 5,000 characters long. And I use traditional characters too, because I prefer a 1:1 mapping of meaning to character.
So a 10% increase shouldn't be a big deal if you're already (somewhat) used to writing them out.
As a current ECE undergrad, I have a few things to say.
Yes, power point (and other computer technologies) are very useful for specific tasks, such as presenting videos, showing complicated graphs, and long code listings.
But when it comes to learning and understanding, and especially learning the theory behind a method, watching the professor work it out with chalk (or markers, whatever) is immensely more valuable than seeing the results print, phrase-by-phrase, on a screen.
Add this to the fact that power point presenters typically dim the lights, mumble the words on the screen, and typically have a 5-minute overhead time spent "playing with the computer" trying to find their files, figure out why the font is wrong, etc.
Many have pointed out that it comes down to the quality of the teacher. And this is true. But to link causality to cause, if the teacher relies too heavily on powerpoint, they probably suck at teaching with any method.
Learning from a all powerpoint lecture is sort of like learning from a set of flashcards. Are they really that different? Except for animations or mulit-page code listings, they're about the same, and equally "useful".
Some have pointed out that powerpoint is great if you want to download the notes on your own time. This is true, but going to class and taking your own notes is much more useful. If your notes aren't clear, or you missed class that day, then ask a friend for a copy of the notes. It's that simple, and part of normal "group studying" anyway. Heck, you could even read the text book, do the homework, and go to office hours in the worst case...
Good point -- for closed-source applications, your system has to closely match whatever a particular piece of software was written to run under.
They have some kind of solution for PPC linux, I can't remember what it is though. I think it's a third-party somewhat compatible plugin.
But I think the real desktop linux barrier is the lack of a standard desktop environment. Last time I toyed with desktop linux, just about everything was half-way broken (compared with my mac, that is). Changing around screen resolutions, for example, involved authenticating as root, hoping I chose a valid resolution, and restarting the X Window system. Dragging a file from a web browser to the desktop -- make a link? save the file? How about dragging an mp3 from xmms to an email. Not likely to work. Oh, and cut/copy/paste... don't get me started!
Linux is a great server environment, and also a good graphical environment for specific non-general purposes, but I think it has a very long way to go before it's a real desktop os alternative.
So until they work all this and more out, I'm sticking with Mac OS X... unix, graphics, multimedia, and industry support... good stuff imo :)
The reason your post is "invalidated" is that you seem to suggest that if the kernel could emulate x86 instruction execution, then the article's author's problems would be solved.
Yet it's obvious, with modern linux distributions, you don't need to worry about if a program is already compiled for intel. You have bigger problems, like the graphics on the ps3, or how the os organizes its libraries, etc.
>Would it be too slow to load a slim PPC kernel and replace init
>with an optimized PPC-compiled qemu instance (basically; it
>would require much more than this) and run a virtual x86
>machine on that?
I mean, why? Why would any linux user need compatibility with another chip? To run linux apps compiled for the other chip? You've got to be kidding.
To run wine? And then run windows? Windows what? 3.11? Nothing modern will run well in this crazy proposed setup. The cell processors will indeed "deal with it" but in the years you would spend doing this, you won't accomplish anything useful when you're done.
And so that's why the parent poster "invalidated" your post.
>Since the PS3's Cell Processor is PowerPC based, you won't be
>able to use any Linux software that's compiled for x86, which is,
>unfortunately, most of it.
I have to say, to most linux users, the specific architecture and processor really aren't meaningful. The linux kernel, gnu userland, and associated popular applications have always been distributed in source code first, and binaries as they are made available. The entire concept of open-source depends on source distribtion.
It is absolutely no problem if an app is distributed in source form or binary (compiled). True, a "standard" linux install base, while it may be defined, is rarely realized. So you could argue that distributing in source code creates problems because needed dependencies can't always be met. But then again, this doesn't help with binary distribution either. Ever try to install an RPM on a non-rpm-ish linux distro? It can be done, yes, but it involves a lot of details. Just as compiling does.
Debian is awesome for distributing such a wide range of apps compiled for so many architectures. But it is truly sad to see someone write that it is "unfortunate" that most linux installs are x86 and his is ppc. The entire concept of linux is that linux is a kernel and a userland distributed in source. It doesn't matter what hardware you have (within reasonable limits... toasters, watches, etc).
There's nothing "unfortunate" about an intel chip, a sparc processor, or a power pc, in terms of the ability of linux to run on it. It's a bigger deal if you're running generic pc hardware with some new video or wifi card. But even this sort of par for the course these days.
He's right. Unless the S-video source contains some extremely high-quality components and filters, you're better off with composite.
Simply:
http://technologizer.files.wordpress.com/2009/01/atari_tablet_XX.jpg?w=535&h=361
Where XX = 0 to 13.
> what's the opposite of coffee?
Ginger. Coffee is a basal vasoconstrictor, and ginger is a vasodilator.
So coffee lowers the blood flow to the brain, and ginger increases it. Don't take both at once unless you enjoy headaches.
In Arizona, you don't cool computer, computer cools YOU!
http://blog.ltc.arizona.edu/ltcannouncements/archives/2008/07/green_ice_disco.html
Central chilled water runs through the supercomputer and cools the room too.
Right on!
Your knowledge in IT probably does help you do your job, but your business, management, and people skills are entirely paramount.
It's the headline, for sure.
I bought a sun box at goodwill once and besides an intact customer database for several large companies, it also had the admin's personal backup files, including his "My Documents" folder, his Palm cell phone, and 1200 dpi scans of his passport. Oh, and some file called "passwords.doc". No idea what is in there...
More details here:
http://lfnet.net/blog/?p=41
But yeah... wipe it before you get rid of it.
You've said nothing about the conditions of the land/property. All you have done is emphasized /who/ would own it.
Personally, my set of conditions is not dependent on who owns it, but how they manage it.
Maybe I'm not understanding your point, but it takes a LOT of energy to power an electric pizza oven. The small toaster oven at my house uses over 1000 watts. I'm sure a larger electric pizza ovens use a lot more. The $40 one at sears.com uses 950 watts.
This doesn't minimize her invention though -- I'm sure any kind off coal or wood-burning oven would work if you were careful.
Legally, your apartment complex MAY NOT prevent you from putting a "reasonable" size TV antenna up on the roof. You're allowed by law to do so. The law exists to prevent people from feeling "forced" to get cable instead of using OTA antenna.
http://www.fcc.gov/mb/facts/otard.html
Tell your apartment complex you'll buy the most reasonable antenna that does the job, and you'll also pay a qualified installer (unless they want to do it). If they say no, show them the law in the most kindest way possible.
Indoor antennas will never get you good results, especially at the bottom of a 3-story building.
That's interesting about the RSSI. Similar to RST with radio communications:
http://en.wikipedia.org/wiki/RST_code
There are actually standards for measuring receive strength. In the world of Amateur Radio, as well as commercial radio communications, we have something called the S-Unit. On some radios, these are displayed on an analog meter, and on some radios, they are displayed as "bars" on an LCD or with LEDs.
Basically, each division ("s unit") is ideally about 6dB different than the next, meaning a signal must double in strength twice to make a 1 s-unit difference. The top or near-top of the scale, called "S9" is typically calibrated at around 50 micro volts (at 50 ohms).
Wikipedia has more information:
http://en.wikipedia.org/wiki/S_meter
The point being, there is a standard for measuring signal with bars. Of course, manufactures don't always adhere to it. In the case of cell phones, who knows. But they probably could...
Wouldn't the GPS only tell your air seed? How would the GPS know if you were traveling at an incline? The Officer's radar gun measures the velocity on the road. The GPS probably compares your coordinates over a short time period and computes your velocity -- hardly accurate if you're traveling at an angle. Unless it's somehow able to factor this in as well. Anyone know?
There's nothing worse than watching a teacher "play computer" while you're trying to learn. It is a major distraction, and generally uses a lot more time than simply demonstrating a technique or example on a standard dry-erase or chalk board.
I once had a teacher who did everything with powerpoint and a wacom tablet. He never touched the chalk. And it was cool at first, because he had the ability to look things up on the internet, review his notes from the previous lecture, and even change his slides when he noticed mistakes.
But for me, I didn't learn much this way. Besides the fact that the lights were darkened (which made me sleepy), he would spend at least ten to fifteen minutes each day doing things like opening files and clicking on various dialog boxes. Had he simply used the three sliding chalkboards, very little time would have been wasted.
There isn't ANYTHING in physics, chemistry, or math that can't be represented fully on a chalkboard by a competent educator.
And I've had the old school teachers that abide by this notion. They really know their stuff. You think you need computer graphing software to demonstrate trig, calculus, or algebra? Previous generations got to the moon and back without much more than a slide rule and a 15-lb calculator. If you're an educator, and you find it more efficient to use mathlab or whatever instead of just drawing the darn thing, than please do kids a favor and step aside.
Even though you might be good at using the computer, if you can teach kids how to understand these concepts with nothing more than a piece of paper and a pencil, then you'll be lowering their reliance on graphing calculators and computers. Yes, these things are useful, sure, but when it comes to learning, better to learn the concept without the bells and whistles.
Call me old school, and I'm cool with that.
Just type 'say' and press return. Now type a phrase. Press return. You can now just type what you need to say and press return after each phrase, rather than typing 'say' each time.
The day I broke up with my x about 6 years ago, I decided to forget her phone number.
Besides not calling her, whenever I would think of the number, I diverted my thoughts to anything else.
Throughout the years, I would half-tempt myself to try and recall the number. Each time, I diverted the thought.
At this moment, if I try to remember the number, I have this feeling that the number is inside my head somewhere, but all those years of training have removed any possibility of recalling it.
I also think if I were to be given the first three digits, I would instantly recall the rest.
Anyone else here have interesting methods of forgetting or recalling?