Re:A couple questions regardign wireless connectiv
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Hawaii Wi-Fi
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· Score: 2
1) Yes. Both antennas are omnidirectional, only one is much longer and has a lot more gain (the tiny flip antennas typically have around 2-4 dB, and remember one dB more is double the signal strength). So a 15 dB antenna is around 8x as powerful (with amp over 20x). It's like an ultra wide-angle telescope, only for radio waves.
2) If all 256 users are connected, they do not all share the same 11 Mbps bandwidth. In fact, the overhead of a wireless network is typically around 3 Mbps, so you only really get around 9 Mbps max of useable bandwidth.
Of course, 9 Mbps is still a lot and makes for *great* web browsing, with a few users doing multimedia applications like streaming video/audio or downloading/uploading large files. What we have found is that if you can match your Internet pipe with the connection it works almost flawlessly as far as heavy load goes (e.g. get a 10 Mbps fractional T3). The network only starts to get slow when things start backing up at our land-line and the clients constantly have to resend data. That's what you have to watch out for -- dropped and resent packets. Those kill the network and are usually from a slow landline.
Hook up a 56k to a WAP11 and load it with 10 users and then try to access a file on a nearby computer. You will be suprized the network is quite slow for something that should be fast.
Anyway, hope this helps!
Re:How To Do It Yourself
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Hawaii Wi-Fi
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· Score: 2
Automatic Gain Control (AGC) does two things really:
1) In situations where a connected antenna has low enough gain, it makes sure the amplifier outputs at the spec power rating (1W for example). Normally, amplifiers have huge tolerances as far as their output power, some common quotes are 500 mW to 1W.
2) It senses the gain of the antenna it is connected to, and if the gain of the anstenna and the amplified signal exceeds a specific threshold, it lowers the amplification power. This keeps the emmited signal at the maximum legal limit -- nothing more, nothing less.
This can be good in #1, but often times can result in using only a fraction of the amplifier's power when connected to an already high gain antenna. This is why I would specify it only for the paranoid.
For those who wouldn't mind, they can exploit a non-AGC amplifier by using it with a slighly higher rated DC injector, thus gaining even more power than the rated 1W. Of course, this has other life time implications, but I have been doing it and I find I can get an additional 200 mW out of a 1W amp without much widening. This is considerable, because a regular WAP11's output (hacked or not) is well below 200 mW, in the 120 range.
I doubt the FCC cracks down on over limited 2.4 GHz networks, at least now anyway. They're too busy chasing pirate radio and HAM's who blast their signal ten times over legal limit. But that comes to the fact the FCC isn't who usually reports you. Cell phone companies may use this frequency for something (900 MHz is what they normally use, but you never know since they're in the pro-RF field), and when they find your signal they may have some corporate policy on reporting you.
So I would be careful and selective at where I put my gear. In our setup, we use stuff we can afford to loose (relativly) and make sure it's hidden so the unaided eye can't see it (read: if you're someone trying to spot an antenna after you have triangulated it). This isn't really for the FCC, but for people who would like to get in on our $200 antenna and $300 amp.
Re:How To Do It Yourself
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Hawaii Wi-Fi
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· Score: 3, Informative
Here is a link to one of the many 15 dB omni's available for the 2.4 GHz spectrum:
http://www.hyperlinktech.com/web/hg2415u.html
Yes, it really does 15 dB. I've tested it.
Re:I have a question.
on
Hawaii Wi-Fi
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· Score: 3, Informative
The 26 mile quote in the article was probably regarding a directional antenna on a base station. Of course, Hawaii doesn't have the buildings and urban sprawl of most other places in the US (or world for that matter), so it may be resonable to assume an amplified antenna on a high peak or mountain would receive such omnidirectional range. At least I would suspect Hawaii would have better range than in the states where there is a lot more RF in the air.
Or it could just be that the news article had it's wording wrong, and that he's actually operating 26 miles from his T1 land line via an array of 802.11b base stations.
How To Do It Yourself
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Hawaii Wi-Fi
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· Score: 5, Informative
What this guy has accomplished here would really be a no-brainer for most on Slashdot. The only thing I can see stopping one is the financial aspect -- an even that's not high. $1000 will create a 256 user, 5 mile 802.11b omnidirectional network or a 25 mile PtP. Myself and three others are setting up a public network in Athens, Ohio. You would be amazed at how many cities will allow you to co-locate antennas on public service towers and buildings when you bill the service as non-profit and for the community.
Here is a low-down of the basic equipment needed for a high-range, omnidirectional base station:
- 15 dB 80" Omnidirectional Antenna - 1W AGC Amplifier - Linksys WAP11 (or your favorite AP here) - N to N male Connector (amplifier to antenna) - BNC to N male Connector (AP to amplifier)
All of the above cost under $800, and when situated in an area with good radio horizon, you can expect 11 Mbps for at least a mile, and 2 Mbps up to 10 (in some cases). Please note that it's against FCC regulations to operate a 2.4 GHz link at 1W with a 15 dB antenna. I doubt anything would come of it since it's not a huge increase over the limit in this area of the spectrum, however for the paranoid you should use an automatic gain control amp that adjusts power automatically to keep you legal.
Other than that it just depends on how much money you have to invest in these base stations to provide wireless roaming. What we have found is that two stations located near enough each other that they overlap tends to increase the power somewhat and allow more users on the system.
This is really the future. Once enough cities grow their own public wireless networks and the technology gets up in the 100 Mbps range (802.11a is not applicable as the range is very limited) at the current distance and power, we can say goodbye to the telecommunications giants for most things.
I have a feeling this made news just because of it's affiliation with the CIA -- the all powerful super secret spy agency of the US government. I sure wish I could generate news stories by doing recursive whois reports and DNS queries.
What's next? I would think that if you were not able to map the CIA's unclassified public network than they must have some sort of major DNS problem.
There is absolutely no significane to this news story other than organizations who maintain a publically accessible web site with such services as e-mail and a web site must have a logical network structure to deliver said services. The CIA is no exception.
What I find most interesting about all of this is the statement about repairs being too risky and to just let the thing leak itself to death, hopefully while building a new tunnel.
I agree with the lawyer in this case -- this seems like a really serious problem, with the capability of affecting many, many people. NYC has already had it's share of disasters, hopefully a city-wide water failure won't be next.
I was also thinking about that 1958 inspection, and the statement in the article about how draining a high pressure underground tunnel can be very dangerous to it's structure. Is it possible that a significant amount of damage occured in the '58 jeep tour, when the tunnel is drained? The sources at hand even state the sink-hole was created around this time, so possibly the ignorance of the past and an inspection is to blame for these leaks?
All I can say is I hope they will do something preventative. How big is the risk to do repairs vs. building a new tunnel? Hopefully we will all have water in a few years! This news (including the 12-year cover up) is certainly interesting to know...and it's been going on all along under our feet!
I wouldn't take much risk with something as fundamental as water.
Why doesn't the SDSS code up a distributed program like SETI to help in the analyzation of all that data to find something unique or unknown. Convert the pictures to 2D FFT's and have a set of known astronomical element FFT's and then do constant comparisons against this set to see if there is anything "unknown". I'm sure it would be more complex than this, but this is how visual image recognition works so I assume it could be tailored for this application.
I would certainly download an run an application that looks for new things in astronomy. I'm sure others would as well. Somehow it's slightly less frivilous than what SETI is doing and we stand to gain more in a quicker amount of time.
That way, when we do actually find something that looks interesting SETI would know where to point that big antenna...
What about if Limewire, who have a significant installed client base invested in the Gnetulla network suddenly desides to refuse connections to, say, BearShare?
IMO, it would come down to who has more clients, like soldiers in a war, and that's who would win. Meanwhile the P2P network will become a desolate war zone.
So in a way you CAN control P2P by controlling the software. Get a high % of users using your client and suddenly change the protocol = controlling which clients can and cannot connect.
A good analogy to how this works would seem to be segmented downloading. On a fast connection, a segmented download splits up a file into chunks and then opens multiple connections on the same interface, and this tends to utilize more of the available burst bandwidth.
Despite the error in this, splitting up a program into two threads to run on one processor seems logical. It affords for advances in parallism, which is what processors (even single) like and optimize for. This way if two threads are running, one can be making heavy use of the ALU and the other the FPU, which are physically seperate areas of the processor, instead of one section sitting idle while to other reports 100% usage to the OS. One thread can be loading and moving data into memory while the other does number crunching...AT THE SAME TIME.
This seems like a very good model, and I can see where it would increase performance by a huge magnitude if implimented on RISC systems, since instructions typically take only a few clock cycles to complete, and most programs are written to perform them sequentially. In hyperthreading, the processor could deal with several instructions at once (like they do already), only the difference would be these wouldn't be JMP guesses or preparing executed code in case of a branch.
Cool stuff, Intel is in the right direction. It would be interesting if someone would write a program to test an ideal HT condition, like a program with two threads, one doing logic stuff and the other floating point. What would the performance increase be?
What I really hate about jobs -- especially those in the IT field and especially those where product development is involved, is managers who are more procedure oriented than they are concerned about our project. They're the "can't see the forest for the trees" type people.
Most of the time they're so preoccupied with doing things by what the 'book' says, even when it's horribly inefficient and not suited for the specific task.
Most of the time managers who don't know what they're doing and those who come from managing non-IT backgrounds. Beleive it or not, HR in some companies will hire managers who have simply been trained to manage in any type of business -- be that retail, industrial, even restraunt! They have no clue what it takes to manage a group of programmers, how to descpline them, hire & fire, etc. Most don't even have a firm grasp of what it is the project is doing.
When faced in these types of situations, I have found you can do three things. The first would be to gradually take the place of the manager. Start to pick up things that the specific manager is doing rather poorly, out a "special respect" toward that manager. They'll think it's flattering -- while you'll be moving in on their turf. Pretty soon you can plead your case to HR once you have eliminated them completly, and they'll get fired while you move up a position and take command once and for all. Unfortunatly, many managers can sense this, although not all, so I would be cautious, as when they since their job is in jeopardy, yours will be soon.
The second is to ride the boat. If you don't care about your resume for this position or intend to simply blame it on management, here is a good option to relax and enjoy personal projects while realizing you're working on a project that will never come to be. It's a bit dishonest, but it pays.
The third is simply to find some place else to work. Do a combination of #2 while you look for a job.
Those here who say change your attitude simply have never worked with a really bad project manager. One who seemingly makes arbitrary decisions in development, and calls meetings to discuss the thing they heard about on the news called "P2P" and wonder how we can integrate it into our word processor. These managers need to have their position pulled right out from under them and put where their only concern is managing people, not a living project (e.g. a retail environment).
What about a kite? I remember getting my nice Into The Wind kite up to the clouds (or what seemed like it) when I was younger, and leaving it there all afternoon, or overnight to find it still there in the morning. Storms often brought it down, most likely breaking the string and not the kite itself.
However, that is really interesting. I assume a very high strength kite coupled with high strength string and a coax up the side with VERY good lightning and surge protection, and you would have a very good line of sight to 10's of miles away (limited by the curvature of the earth and your altitude?). All I would be concerned about would be lightning protection, kite stability, and signal loss from long length cable.
Other than that, it's an interesting idea. Anyone else care to comment?
Did it ever occur to you these clowns are using an e-mail fax service, which bills by page amount and not time? So you're actually costing the innocent fax service money, not the spammer.
I appreciate and agree with many of your views. I was going to mention shareholder return in my post, but wanted to keep the metaphors short and to the point.
Companies are obligated to give a shareholder return -- there's no question of that. However, they are also required to do what is best for the public and find a good balance between that and return. Personally, I would rather have my stock a few dollars less if it means I'm not supporting censorship and possibly the deaths of those who express ideas which don't agree with the government.
There are more things than money -- like integrity and dignity. More companies should learn to be both economically and socially responsible. In this case, Cisco certainly isn't.
Give me a competitor with equivilent products and I'll glady take my business else-where. As a Cisco supporter for a long time, I have to say this will strike a blow to customer loyalty.
I wonder if they're going to loose more businnes than they gained in the bad PR this will create..e.g. would you want products in your organization that have been funded by communist profits?
Sometimes it's best to say: "Take your business some place else.". That's all Cisco had to say, and that's what they should've said. Maybe then the government would have given up on their massive firewall and settled for flimsy IP filtering instead.
As far as I am concerned, Cisco's lack of refusal indicates they are no different than the companies who supplied Germany with the machines to torture and suppress their citizens. It's one thing to supply products and have a customer misuse them, but another to give someone a loaded gun knowing well-enough they're going to go kill someone with it.
It's just plain wrong -- we're talking about freedom and people's lives here. Capital gain pails in comparison.
Of all the rhetoric in this very disturbing piece of how western companies are helping censorship overseas, I found this comment most interesting:
"We don't care about the [Chinese government's] rules. It's none of Cisco's business."
Similar to how Mercedes or BMW didn't care much for what those giant ovens were used for in NAZI Germany, because it was none of their business. Oh how the ashes fall.
Disgusting. I can say I will never think of Cisco the same way again. What if the US decided they needed to "monitor" citizen Internet communications? Would Cisco step up with one of their enterprise level solutions?
Right next to Oracle with bids for a national ID card...
I don't mean to be rude but another solution, if you're running windows, is to try to find a cure for cancer, or alzheimers, or anthrax, instead of looking for extra-terrestrial life.
Yeah. Why bother looking for such trivial things as life in the universe besides us? Why should we have gone into the rain forest just for the sake of going? Let's forget about we found a new type of antibiotic in the process.
Why should we do things with no clear prospect of return? Well, one could argue we do them for science. You know? That old thing that leads to new advances in humanity? One could argue that great discoveries are often by accident. That means by looking and doing something new -- not always directed toward solving the problem at hand -- leads to a solution of a major problem.
What does all of this have to do with searching for aliens? Well, it means we shouldn't stop doing something that some here might think as trivial or un-worldly, just because there are other issues at home. There will always be issues at home. Curing cancer, in many ways, is just as big a task as SETI@Home. It's the same as those who questioned the spending of millions of dollars for the space program, and that sending a man to the moon was stupid since we couldn't even solve our own problem of where to put and feed our own people.
Well, what has gone to the moon given us? Certainly not a cure for cancer, at least not directly. What is has done is captured the imaginations of all those who were glued to the TV when those infamous images were sent back...Maybe a few of those millions have actually gone on to become doctors, engineers, etc. who have cured a disease or solved a new problem for humanity. It represented something new, raised hopes for people during that time and allowed many to live vicariously and not be concerned with current "at home" issues like finding a job or worrying about the war.
There is a lot of merit for science dedicated toward application and I don't have any problem with, say, searching the a cure for cancer or Alzheimers. But the argument of there are better things to do is like the argument of "People are wasting bandwidth for trivial uses, that's why the Internet is so slow.".
We should all dedicate our efforts toward solving our present problems, but we should always save a little to go to the moon once in a while...
This reminds me of when I first heard of Linux, way back in 1993 when I was on CompuServe, using the new NCSA web browser for the first time in Win 3.1.
In the page I read on an academic web site, it described Linux as a principle of reusing old hardware with better software, which was odd because it missed the whole open source community thing.
I am glad to see that older hardware is going to become widely supported in commercial distributions instead of having to roll your own.
Well I recently got an entry-level position in a large corporate enviornment, doing IT related stuff. I was surpized at the sophistication of the mail system in place for both dealing with spam and making sure company contact addresses (since there are thousands of new e-mail contacts established daily) are not blocked along with the adds for penis enlargement.
Our policy is to filter mail based upon client (e.g. employee) preference. If our client requests so, they can ellect to receive all mail, including any SPAM. If they want to, they can get SPAM from known spammers delivered to a specific folder, which is created when they download their folders in Outlook. They can block all mail except for known addresses. Domains they have ever sent mail to get put in the accept table automatically, with exception to a few (most notably hotmail and the like).
Another method we use is filtering bulk mailings. If a sever from X IP is connecting up everyday and spending several hours delivering mail to every address, you can bet that's spam and is thus filtered or at least flagged for human investigation. There are only a few major domains that deliver to a large percentage of our user base, such as humor mailing lists. And because spammers frequently change IPs, any IP delivering to over 20% of the population, which would easily be over 1,000 addresses, is flagged for review.
We have also found that often times spammers are setting up fake networks in areas of IPv4 that aren't even allocated to any network. We have even seen IP's connecting up which are supposed to be in the ameture radio range. This is either done via false route information to a helpless upstream ISP or spoofing in some way. This is increasingly common, and we have found doing a reverse-lookup on the IP address and reported hostname in ARIN works very well in stopping this. If it doesn't match, the mail is sent to the spam folder. This also works for people running dynamic DNS services on their DSL or cable connections, BUT with a registered domain name. So when you do a lookup on their domain, you get their IP address and can't tell it's on a cable or DSL network, unless you do a reverse lookup and compare the results. A true business doing a lot of e-mails will have an entry in ARIN. However, we use this with caution because it tends to flag e-mail from virtural web hosts or sites who aren't big enough to have their own netblock.
I think the solution to spam is to use the black-lists, but only within reason. I agree with many here and I also think the purpose of the lists should be to eliminate spam via open relays, and this should be done via closing those relays, not
'blacking' them out. Most are simple Netscape server-folk who have all kinds of other services open as well, including proxy, web cache, etc. and they need the blacklists to work with them to eliminate these problems.
I find the methods I've described an acceptable compromise. Although it doesn't solve the problem of wasting bandwidth, the risk is too great a valid corporate contact could be filtered due to various reasons, and the business would be lost. In a real corporate environment (read: not your home network of 5 linux boxen), you can't afford to block a complete, half, or even 1/4 of a subnet due to one abuse. There could be a client only one IP away who doesn't get through and decides to go somewhere else...
Often times they do...do a tracert on any UUNET dialup and find the dialup server and dump the MIB tree. I think you will be suprized at the information you can learn AND change.
Will your wedding be open admission to all the slashdot crowd? Have someone at the entrance hooked up with a slashdot db and you give them your username and pw to get in...
You better have a wireless LAN there (for checking slashdot of course) and be prepared to say no to those trying to bring in their watercooled Athlon systems.
Seriously, though, this is really cool. It's a little cliche, but oh well the main point is it worked. Congrats to you both!
The only so called flaw in SNMP is when huge provider backbones like UUNET and AT&T leave the write community string to the default "private" using the original SNMP protocol set and not the new version which supports secure communications and authentication.
I come across routers all the time on pipex style networks with fully modifiable MIB trees. This could include changing route interfaces, route metrics, disabling or turning off a router, etc. as well as viewing sensitive network information.
Other than that which is a huge hole per se, but not really relating to a deficiency in the protocol but only in the administration of said protocol. Maybe there's some buffer overflow problem or something other, but one thing is for sure -- any network device which has any merit at all has SNMP managemenet built-in, and is thus affected. This includes your typical Internet routers, your cable and DSL modems, your smart HUBs and switches, line monitoring devices, QoS networks, and any network operating system (Win2k, Linux, BSDs), etc.
Hmm, this is nothing new. You, yourself, can buy a several watt (yes watt) IR diode and modulate it using an AOM to at least 100's of Mbits a second and more very easily for under $1500. This would easily reach a target for miles if the reciver made use of a dichroic narrowband filter and some good ECC. However, as mentioned, line of sight must be maintained.
Divergence, not mentioned in the article, is also an issue. Especially with laser diodes, it doesn't matter what kind of miracle anamorphic lens system you have to decrease the divergence of the beam, becuase pretty soon that pencil thin dot is going to become several feet in diameter. THIS is what accounts to loss more than so called 'atmosphere' causes. Photodiodes/transistors operate at a power/cm^2 ratio, and the lower this is out of the rated area the more noise. So when the beam spreads out, the concentration of power thins out and you get noise because although all your signal is getting there, you can only sample a small fraction of its power. Having low divergence also works against you because it makes the system much more difficult to align. I would start with a very large beam, just enough to get a signal, and then progress to the smallest beam possible. Vibrations at the transmitter site will likely limit this, as tiny shifts in movement only a mm will cause the beam to jump several feet miles away.
Many here have mentioned the speed is on the slow side for this technology. Well, folks, this is optics and that means you can do things in parallel. If you need more speed, just shift the wavelength of the diode and multiplex it in. This is the same principle behind DWDM systems, only it's in freespace. You don't even need a fancy FB diode to do it -- most commercial diodes have a 30 nm linewidth, and by controlling the voltage and temperature you can easily shift up or down. In any case, adding another same-wavelength line is just as easy as adding another transmitter/receiver pair at either end. If only you could do that for fiber. Instead, you have to dig up the streets.
I have had the pleasure of working with a system from Coherent that really makes free space communications shine. The system automatically adjusts and aligns itself via electronic gyros and GPS. It tells you if the current location even has any type of line of sight and if it does it zeos in on the beam (e.g. "I'm pointing S-SW, can you see me?"). The hardest thing is you must have a current connection to the other end while performing the alignment, but this was easily accomidated for at my location with a cellular modem.
This stuff is really cool and there are definate applications for anywhere that has good line of sight. For example, cell towers frequently have good line of sight to one another, so this technology would make sense for that application. There are enough towers that the network could be constructed in a serial or star configuration, without the need for many land lines near the tower.
What would be even cooler would be somehow using the high voltage transmission towers and installing a small, low cost module on each one to jump from tower to tower, or even pole to pole. Since it's optical, you don't have to worry about interference or expensive shielding (yes, there are all-optical transceivers out there).
These are just some ideas but the technology itself finally seems to be maturing. There are lots of current applications and it seems that although most carriers have loads of dark fiber underground, so the cable isn't really the problem, but maybe these companies will help drive bandwidth prices down by enabling small yet very fast ISPs to pop up and use the technology without having to haggle over ground cable. The Internet Revolution per se, isn't going to continue until we all have true broadband (10 Mbps or more, preferably 100 Mbps) to the curb for $19.95 a month.
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1) Yes. Both antennas are omnidirectional, only one is much longer and has a lot more gain (the tiny flip antennas typically have around 2-4 dB, and remember one dB more is double the signal strength). So a 15 dB antenna is around 8x as powerful (with amp over 20x). It's like an ultra wide-angle telescope, only for radio waves.
2) If all 256 users are connected, they do not all share the same 11 Mbps bandwidth. In fact, the overhead of a wireless network is typically around 3 Mbps, so you only really get around 9 Mbps max of useable bandwidth.
Of course, 9 Mbps is still a lot and makes for *great* web browsing, with a few users doing multimedia applications like streaming video/audio or downloading/uploading large files. What we have found is that if you can match your Internet pipe with the connection it works almost flawlessly as far as heavy load goes (e.g. get a 10 Mbps fractional T3). The network only starts to get slow when things start backing up at our land-line and the clients constantly have to resend data. That's what you have to watch out for -- dropped and resent packets. Those kill the network and are usually from a slow landline.
Hook up a 56k to a WAP11 and load it with 10 users and then try to access a file on a nearby computer. You will be suprized the network is quite slow for something that should be fast.
Anyway, hope this helps!
Automatic Gain Control (AGC) does two things really:
1) In situations where a connected antenna has low enough gain, it makes sure the amplifier outputs at the spec power rating (1W for example). Normally, amplifiers have huge tolerances as far as their output power, some common quotes are 500 mW to 1W.
2) It senses the gain of the antenna it is connected to, and if the gain of the anstenna and the amplified signal exceeds a specific threshold, it lowers the amplification power. This keeps the emmited signal at the maximum legal limit -- nothing more, nothing less.
This can be good in #1, but often times can result in using only a fraction of the amplifier's power when connected to an already high gain antenna. This is why I would specify it only for the paranoid.
For those who wouldn't mind, they can exploit a non-AGC amplifier by using it with a slighly higher rated DC injector, thus gaining even more power than the rated 1W. Of course, this has other life time implications, but I have been doing it and I find I can get an additional 200 mW out of a 1W amp without much widening. This is considerable, because a regular WAP11's output (hacked or not) is well below 200 mW, in the 120 range.
I doubt the FCC cracks down on over limited 2.4 GHz networks, at least now anyway. They're too busy chasing pirate radio and HAM's who blast their signal ten times over legal limit. But that comes to the fact the FCC isn't who usually reports you. Cell phone companies may use this frequency for something (900 MHz is what they normally use, but you never know since they're in the pro-RF field), and when they find your signal they may have some corporate policy on reporting you.
So I would be careful and selective at where I put my gear. In our setup, we use stuff we can afford to loose (relativly) and make sure it's hidden so the unaided eye can't see it (read: if you're someone trying to spot an antenna after you have triangulated it). This isn't really for the FCC, but for people who would like to get in on our $200 antenna and $300 amp.
Here is a link to one of the many 15 dB omni's available for the 2.4 GHz spectrum:
http://www.hyperlinktech.com/web/hg2415u.html
Yes, it really does 15 dB. I've tested it.
The 26 mile quote in the article was probably regarding a directional antenna on a base station. Of course, Hawaii doesn't have the buildings and urban sprawl of most other places in the US (or world for that matter), so it may be resonable to assume an amplified antenna on a high peak or mountain would receive such omnidirectional range. At least I would suspect Hawaii would have better range than in the states where there is a lot more RF in the air.
Or it could just be that the news article had it's wording wrong, and that he's actually operating 26 miles from his T1 land line via an array of 802.11b base stations.
What this guy has accomplished here would really be a no-brainer for most on Slashdot. The only thing I can see stopping one is the financial aspect -- an even that's not high. $1000 will create a 256 user, 5 mile 802.11b omnidirectional network or a 25 mile PtP. Myself and three others are setting up a public network in Athens, Ohio. You would be amazed at how many cities will allow you to co-locate antennas on public service towers and buildings when you bill the service as non-profit and for the community.
Here is a low-down of the basic equipment needed for a high-range, omnidirectional base station:
- 15 dB 80" Omnidirectional Antenna
- 1W AGC Amplifier
- Linksys WAP11 (or your favorite AP here)
- N to N male Connector (amplifier to antenna)
- BNC to N male Connector (AP to amplifier)
All of the above cost under $800, and when situated in an area with good radio horizon, you can expect 11 Mbps for at least a mile, and 2 Mbps up to 10 (in some cases). Please note that it's against FCC regulations to operate a 2.4 GHz link at 1W with a 15 dB antenna. I doubt anything would come of it since it's not a huge increase over the limit in this area of the spectrum, however for the paranoid you should use an automatic gain control amp that adjusts power automatically to keep you legal.
Other than that it just depends on how much money you have to invest in these base stations to provide wireless roaming. What we have found is that two stations located near enough each other that they overlap tends to increase the power somewhat and allow more users on the system.
This is really the future. Once enough cities grow their own public wireless networks and the technology gets up in the 100 Mbps range (802.11a is not applicable as the range is very limited) at the current distance and power, we can say goodbye to the telecommunications giants for most things.
I have a feeling this made news just because of it's affiliation with the CIA -- the all powerful super secret spy agency of the US government. I sure wish I could generate news stories by doing recursive whois reports and DNS queries.
What's next? I would think that if you were not able to map the CIA's unclassified public network than they must have some sort of major DNS problem.
There is absolutely no significane to this news story other than organizations who maintain a publically accessible web site with such services as e-mail and a web site must have a logical network structure to deliver said services. The CIA is no exception.
What I find most interesting about all of this is the statement about repairs being too risky and to just let the thing leak itself to death, hopefully while building a new tunnel.
I agree with the lawyer in this case -- this seems like a really serious problem, with the capability of affecting many, many people. NYC has already had it's share of disasters, hopefully a city-wide water failure won't be next.
I was also thinking about that 1958 inspection, and the statement in the article about how draining a high pressure underground tunnel can be very dangerous to it's structure. Is it possible that a significant amount of damage occured in the '58 jeep tour, when the tunnel is drained? The sources at hand even state the sink-hole was created around this time, so possibly the ignorance of the past and an inspection is to blame for these leaks?
All I can say is I hope they will do something preventative. How big is the risk to do repairs vs. building a new tunnel? Hopefully we will all have water in a few years! This news (including the 12-year cover up) is certainly interesting to know...and it's been going on all along under our feet!
I wouldn't take much risk with something as fundamental as water.
Yeah, heh, too early in the morning.
I can think of a good application for this data.
Why doesn't the SDSS code up a distributed program like SETI to help in the analyzation of all that data to find something unique or unknown. Convert the pictures to 2D FFT's and have a set of known astronomical element FFT's and then do constant comparisons against this set to see if there is anything "unknown". I'm sure it would be more complex than this, but this is how visual image recognition works so I assume it could be tailored for this application.
I would certainly download an run an application that looks for new things in astronomy. I'm sure others would as well. Somehow it's slightly less frivilous than what SETI is doing and we stand to gain more in a quicker amount of time.
That way, when we do actually find something that looks interesting SETI would know where to point that big antenna...
by changing the version number with a resource editor. Quite simple, really.
What about if Limewire, who have a significant installed client base invested in the Gnetulla network suddenly desides to refuse connections to, say, BearShare?
IMO, it would come down to who has more clients, like soldiers in a war, and that's who would win. Meanwhile the P2P network will become a desolate war zone.
So in a way you CAN control P2P by controlling the software. Get a high % of users using your client and suddenly change the protocol = controlling which clients can and cannot connect.
A good analogy to how this works would seem to be segmented downloading. On a fast connection, a segmented download splits up a file into chunks and then opens multiple connections on the same interface, and this tends to utilize more of the available burst bandwidth.
Despite the error in this, splitting up a program into two threads to run on one processor seems logical. It affords for advances in parallism, which is what processors (even single) like and optimize for. This way if two threads are running, one can be making heavy use of the ALU and the other the FPU, which are physically seperate areas of the processor, instead of one section sitting idle while to other reports 100% usage to the OS. One thread can be loading and moving data into memory while the other does number crunching...AT THE SAME TIME.
This seems like a very good model, and I can see where it would increase performance by a huge magnitude if implimented on RISC systems, since instructions typically take only a few clock cycles to complete, and most programs are written to perform them sequentially. In hyperthreading, the processor could deal with several instructions at once (like they do already), only the difference would be these wouldn't be JMP guesses or preparing executed code in case of a branch.
Cool stuff, Intel is in the right direction. It would be interesting if someone would write a program to test an ideal HT condition, like a program with two threads, one doing logic stuff and the other floating point. What would the performance increase be?
What I really hate about jobs -- especially those in the IT field and especially those where product development is involved, is managers who are more procedure oriented than they are concerned about our project. They're the "can't see the forest for the trees" type people.
Most of the time they're so preoccupied with doing things by what the 'book' says, even when it's horribly inefficient and not suited for the specific task.
Most of the time managers who don't know what they're doing and those who come from managing non-IT backgrounds. Beleive it or not, HR in some companies will hire managers who have simply been trained to manage in any type of business -- be that retail, industrial, even restraunt! They have no clue what it takes to manage a group of programmers, how to descpline them, hire & fire, etc. Most don't even have a firm grasp of what it is the project is doing.
When faced in these types of situations, I have found you can do three things. The first would be to gradually take the place of the manager. Start to pick up things that the specific manager is doing rather poorly, out a "special respect" toward that manager. They'll think it's flattering -- while you'll be moving in on their turf. Pretty soon you can plead your case to HR once you have eliminated them completly, and they'll get fired while you move up a position and take command once and for all. Unfortunatly, many managers can sense this, although not all, so I would be cautious, as when they since their job is in jeopardy, yours will be soon.
The second is to ride the boat. If you don't care about your resume for this position or intend to simply blame it on management, here is a good option to relax and enjoy personal projects while realizing you're working on a project that will never come to be. It's a bit dishonest, but it pays.
The third is simply to find some place else to work. Do a combination of #2 while you look for a job.
Those here who say change your attitude simply have never worked with a really bad project manager. One who seemingly makes arbitrary decisions in development, and calls meetings to discuss the thing they heard about on the news called "P2P" and wonder how we can integrate it into our word processor. These managers need to have their position pulled right out from under them and put where their only concern is managing people, not a living project (e.g. a retail environment).
What about a kite? I remember getting my nice Into The Wind kite up to the clouds (or what seemed like it) when I was younger, and leaving it there all afternoon, or overnight to find it still there in the morning. Storms often brought it down, most likely breaking the string and not the kite itself.
However, that is really interesting. I assume a very high strength kite coupled with high strength string and a coax up the side with VERY good lightning and surge protection, and you would have a very good line of sight to 10's of miles away (limited by the curvature of the earth and your altitude?). All I would be concerned about would be lightning protection, kite stability, and signal loss from long length cable.
Other than that, it's an interesting idea. Anyone else care to comment?
Did it ever occur to you these clowns are using an e-mail fax service, which bills by page amount and not time? So you're actually costing the innocent fax service money, not the spammer.
;-)
Now 50 pages of greyscale might be interesting
I appreciate and agree with many of your views. I was going to mention shareholder return in my post, but wanted to keep the metaphors short and to the point.
Companies are obligated to give a shareholder return -- there's no question of that. However, they are also required to do what is best for the public and find a good balance between that and return. Personally, I would rather have my stock a few dollars less if it means I'm not supporting censorship and possibly the deaths of those who express ideas which don't agree with the government.
There are more things than money -- like integrity and dignity. More companies should learn to be both economically and socially responsible. In this case, Cisco certainly isn't.
Give me a competitor with equivilent products and I'll glady take my business else-where. As a Cisco supporter for a long time, I have to say this will strike a blow to customer loyalty.
I wonder if they're going to loose more businnes than they gained in the bad PR this will create..e.g. would you want products in your organization that have been funded by communist profits?
Sometimes it's best to say: "Take your business some place else.". That's all Cisco had to say, and that's what they should've said. Maybe then the government would have given up on their massive firewall and settled for flimsy IP filtering instead.
As far as I am concerned, Cisco's lack of refusal indicates they are no different than the companies who supplied Germany with the machines to torture and suppress their citizens. It's one thing to supply products and have a customer misuse them, but another to give someone a loaded gun knowing well-enough they're going to go kill someone with it.
It's just plain wrong -- we're talking about freedom and people's lives here. Capital gain pails in comparison.
Of all the rhetoric in this very disturbing piece of how western companies are helping censorship overseas, I found this comment most interesting:
"We don't care about the [Chinese government's] rules. It's none of Cisco's business."
Similar to how Mercedes or BMW didn't care much for what those giant ovens were used for in NAZI Germany, because it was none of their business. Oh how the ashes fall.
Disgusting. I can say I will never think of Cisco the same way again. What if the US decided they needed to "monitor" citizen Internet communications? Would Cisco step up with one of their enterprise level solutions?
Right next to Oracle with bids for a national ID card...
I don't mean to be rude but another solution, if you're running windows, is to try to find a cure for cancer, or alzheimers, or anthrax, instead of looking for extra-terrestrial life.
Yeah. Why bother looking for such trivial things as life in the universe besides us? Why should we have gone into the rain forest just for the sake of going? Let's forget about we found a new type of antibiotic in the process.
Why should we do things with no clear prospect of return? Well, one could argue we do them for science. You know? That old thing that leads to new advances in humanity? One could argue that great discoveries are often by accident. That means by looking and doing something new -- not always directed toward solving the problem at hand -- leads to a solution of a major problem.
What does all of this have to do with searching for aliens? Well, it means we shouldn't stop doing something that some here might think as trivial or un-worldly, just because there are other issues at home. There will always be issues at home. Curing cancer, in many ways, is just as big a task as SETI@Home. It's the same as those who questioned the spending of millions of dollars for the space program, and that sending a man to the moon was stupid since we couldn't even solve our own problem of where to put and feed our own people.
Well, what has gone to the moon given us? Certainly not a cure for cancer, at least not directly. What is has done is captured the imaginations of all those who were glued to the TV when those infamous images were sent back...Maybe a few of those millions have actually gone on to become doctors, engineers, etc. who have cured a disease or solved a new problem for humanity. It represented something new, raised hopes for people during that time and allowed many to live vicariously and not be concerned with current "at home" issues like finding a job or worrying about the war.
There is a lot of merit for science dedicated toward application and I don't have any problem with, say, searching the a cure for cancer or Alzheimers. But the argument of there are better things to do is like the argument of "People are wasting bandwidth for trivial uses, that's why the Internet is so slow.".
We should all dedicate our efforts toward solving our present problems, but we should always save a little to go to the moon once in a while...
This reminds me of when I first heard of Linux, way back in 1993 when I was on CompuServe, using the new NCSA web browser for the first time in Win 3.1.
In the page I read on an academic web site, it described Linux as a principle of reusing old hardware with better software, which was odd because it missed the whole open source community thing.
I am glad to see that older hardware is going to become widely supported in commercial distributions instead of having to roll your own.
Well I recently got an entry-level position in a large corporate enviornment, doing IT related stuff. I was surpized at the sophistication of the mail system in place for both dealing with spam and making sure company contact addresses (since there are thousands of new e-mail contacts established daily) are not blocked along with the adds for penis enlargement.
Our policy is to filter mail based upon client (e.g. employee) preference. If our client requests so, they can ellect to receive all mail, including any SPAM. If they want to, they can get SPAM from known spammers delivered to a specific folder, which is created when they download their folders in Outlook. They can block all mail except for known addresses. Domains they have ever sent mail to get put in the accept table automatically, with exception to a few (most notably hotmail and the like).
Another method we use is filtering bulk mailings. If a sever from X IP is connecting up everyday and spending several hours delivering mail to every address, you can bet that's spam and is thus filtered or at least flagged for human investigation. There are only a few major domains that deliver to a large percentage of our user base, such as humor mailing lists. And because spammers frequently change IPs, any IP delivering to over 20% of the population, which would easily be over 1,000 addresses, is flagged for review.
We have also found that often times spammers are setting up fake networks in areas of IPv4 that aren't even allocated to any network. We have even seen IP's connecting up which are supposed to be in the ameture radio range. This is either done via false route information to a helpless upstream ISP or spoofing in some way. This is increasingly common, and we have found doing a reverse-lookup on the IP address and reported hostname in ARIN works very well in stopping this. If it doesn't match, the mail is sent to the spam folder. This also works for people running dynamic DNS services on their DSL or cable connections, BUT with a registered domain name. So when you do a lookup on their domain, you get their IP address and can't tell it's on a cable or DSL network, unless you do a reverse lookup and compare the results. A true business doing a lot of e-mails will have an entry in ARIN. However, we use this with caution because it tends to flag e-mail from virtural web hosts or sites who aren't big enough to have their own netblock.
I think the solution to spam is to use the black-lists, but only within reason. I agree with many here and I also think the purpose of the lists should be to eliminate spam via open relays, and this should be done via closing those relays, not
'blacking' them out. Most are simple Netscape server-folk who have all kinds of other services open as well, including proxy, web cache, etc. and they need the blacklists to work with them to eliminate these problems.
I find the methods I've described an acceptable compromise. Although it doesn't solve the problem of wasting bandwidth, the risk is too great a valid corporate contact could be filtered due to various reasons, and the business would be lost. In a real corporate environment (read: not your home network of 5 linux boxen), you can't afford to block a complete, half, or even 1/4 of a subnet due to one abuse. There could be a client only one IP away who doesn't get through and decides to go somewhere else...
Anyway, just my 2 cents and 5 weeks experience...
Often times they do...do a tracert on any UUNET dialup and find the dialup server and dump the MIB tree. I think you will be suprized at the information you can learn AND change.
Will your wedding be open admission to all the slashdot crowd? Have someone at the entrance hooked up with a slashdot db and you give them your username and pw to get in...
You better have a wireless LAN there (for checking slashdot of course) and be prepared to say no to those trying to bring in their watercooled Athlon systems.
Seriously, though, this is really cool. It's a little cliche, but oh well the main point is it worked. Congrats to you both!
Pretty cool thing...you can see the Slashdot effect in real time. Hit reload and the signature #'s on the page increase by about 2-3 a second.
The only so called flaw in SNMP is when huge provider backbones like UUNET and AT&T leave the write community string to the default "private" using the original SNMP protocol set and not the new version which supports secure communications and authentication.
I come across routers all the time on pipex style networks with fully modifiable MIB trees. This could include changing route interfaces, route metrics, disabling or turning off a router, etc. as well as viewing sensitive network information.
Other than that which is a huge hole per se, but not really relating to a deficiency in the protocol but only in the administration of said protocol. Maybe there's some buffer overflow problem or something other, but one thing is for sure -- any network device which has any merit at all has SNMP managemenet built-in, and is thus affected. This includes your typical Internet routers, your cable and DSL modems, your smart HUBs and switches, line monitoring devices, QoS networks, and any network operating system (Win2k, Linux, BSDs), etc.
Hmm, this is nothing new. You, yourself, can buy a several watt (yes watt) IR diode and modulate it using an AOM to at least 100's of Mbits a second and more very easily for under $1500. This would easily reach a target for miles if the reciver made use of a dichroic narrowband filter and some good ECC. However, as mentioned, line of sight must be maintained.
Divergence, not mentioned in the article, is also an issue. Especially with laser diodes, it doesn't matter what kind of miracle anamorphic lens system you have to decrease the divergence of the beam, becuase pretty soon that pencil thin dot is going to become several feet in diameter. THIS is what accounts to loss more than so called 'atmosphere' causes. Photodiodes/transistors operate at a power/cm^2 ratio, and the lower this is out of the rated area the more noise. So when the beam spreads out, the concentration of power thins out and you get noise because although all your signal is getting there, you can only sample a small fraction of its power. Having low divergence also works against you because it makes the system much more difficult to align. I would start with a very large beam, just enough to get a signal, and then progress to the smallest beam possible. Vibrations at the transmitter site will likely limit this, as tiny shifts in movement only a mm will cause the beam to jump several feet miles away.
Many here have mentioned the speed is on the slow side for this technology. Well, folks, this is optics and that means you can do things in parallel. If you need more speed, just shift the wavelength of the diode and multiplex it in. This is the same principle behind DWDM systems, only it's in freespace. You don't even need a fancy FB diode to do it -- most commercial diodes have a 30 nm linewidth, and by controlling the voltage and temperature you can easily shift up or down. In any case, adding another same-wavelength line is just as easy as adding another transmitter/receiver pair at either end. If only you could do that for fiber. Instead, you have to dig up the streets.
I have had the pleasure of working with a system from Coherent that really makes free space communications shine. The system automatically adjusts and aligns itself via electronic gyros and GPS. It tells you if the current location even has any type of line of sight and if it does it zeos in on the beam (e.g. "I'm pointing S-SW, can you see me?"). The hardest thing is you must have a current connection to the other end while performing the alignment, but this was easily accomidated for at my location with a cellular modem.
This stuff is really cool and there are definate applications for anywhere that has good line of sight. For example, cell towers frequently have good line of sight to one another, so this technology would make sense for that application. There are enough towers that the network could be constructed in a serial or star configuration, without the need for many land lines near the tower.
What would be even cooler would be somehow using the high voltage transmission towers and installing a small, low cost module on each one to jump from tower to tower, or even pole to pole. Since it's optical, you don't have to worry about interference or expensive shielding (yes, there are all-optical transceivers out there).
These are just some ideas but the technology itself finally seems to be maturing. There are lots of current applications and it seems that although most carriers have loads of dark fiber underground, so the cable isn't really the problem, but maybe these companies will help drive bandwidth prices down by enabling small yet very fast ISPs to pop up and use the technology without having to haggle over ground cable. The Internet Revolution per se, isn't going to continue until we all have true broadband (10 Mbps or more, preferably 100 Mbps) to the curb for $19.95 a month.