Nobody is going to be able to tell you how many access points you are going to need to cover the building without knowing what the walls are made of, how thick they are, and what the exact floorplan is (even with that information, it would be a guess).
What you need to do is choose between 802.11B and 802.11G (I'd probably go B for what you have in mind). Purchase the following:
an access point (not a router, an access point)
a pcmcia or usb 802.11b adapter
an omni-directional, high gain antenna for the AP (7-9dbi, slotted waveguide, vertical colinear array, etc)
Install the USB/PCMCIA adapter in a notebook, and start experimenting with access point/antenna locations on each floor. The Access point does not need to be connected to an ethernet drop to test signal strength. Remember that the omni antenna have a horizontal donut shaped radiation pattern, so you need to mount it pretty close to vertical for your tests.
I suspect that you will need 2 AP's per floor, so your cost should look like this (assuming you do all the work):
Internet Connection: ??
8xAccess Points - Dlink DWL-900+: $512 (newegg)
2000' cat 5 pvc cable: $70 (computergate)
16 port switch - DLink DSS16+: $75 (newegg)
Surface mount cat 5 boxes, 3x4 port boxes at switch end, 20 patch cables: $200 (computergate)
Total should be less than $900
The biggest problem you are likely to face is getting power to the Access Points. Power Over Ethernet can be a little bit of a pain to set up if you are now electronically inclined, and building code can be your enemy in terms of running extension cords or additional outlet boxes.
Also remember that there are special code requirements for running any type of cables through a vertical shaft like the elevator shaft. If there is an existing conduit running vertically for phone cabling, that is your best bet.
Also/FYI: my experience is that cheap patch panel antennas are useless. The two I have purchased do not outperform a standard dipole.
I have to disagree on making it an international effort. The more agencies/countries you have involved, the more politics will drive the effort, rather than sound science and engineering.
What they should do is write Burt Rutan's group (Scaled Composites) a big check, and set them loose on the problem.
Also, setting up a manned moon base has lots of benefits both as a scientific/industrial asset, as well as a way to get robotic probes out into space without having to get out of the giant sucking gravity hole we live on. Without the stress of earth launch, we would gain significant cost reductions on these missions, as well as a lot of engineering flexibility. With the low launch costs from the moon, we could take a micro-sat / shotgun approach to solar system exploration.
Sending a manned mission to mars appears to only have political benefits at this point, and looks like it is impractical given the economic and safety constraints such a project is likely to operate under.
It would be very difficult to maintain an accurate surface in aluminum. The current state of the art (afaik) in exotic mirrors is thin carbon-fiber composite mirrors molded on a mandril, then silvered.
The fast majority of homebuilt telescopes are built using glass, pyrex or zerodur (all glasses of various compositions) mirrors. All newtonian telescopes f/8 or slower can sometimes be made with spherical mirrors, everything faster than that requires a parabolic mirror.
Many amateurs polish their own mirrors. A great project if you have the time, and a great project if you have kids, but you'd have to be working at a McJob to come close to breaking even on the time vs purchasing a prefab mirror.
You might want to take a look at Mel Bartels Telescope home page. It contains lots of references on mount design, and a home-brew system for adding computerized goto capabilities to dob scopes.
Depending on your fabrication skills and facilities, you might also want to look into a truss dobson (probably not necessary at 8"), or a split ring mount. The split ring mount is an equatorial mount, making it easy to add a motor to track objects against the earth's rotation. Even if you want to learn the sky for yourself (rather than use a goto system), tracking is very very useful, particularly when sharing the views with others. The split ring also avoids field-rotation at the eyepiece allowing long exposure astro-photography using film or digital cameras.
I started out with a 10" meade starfinder dob, rebuilt it as a truss scope (goto), then rebuilt it as a split ring (motorized but not goto). The Meade starfinder design is very similar to the one you referenced, and is by far the easiest to build.
Be aware that astronomy is a disease, I don't know anyone who uses a telescope regularly and only owns a single telescope.
Mirror mounting and general construction quality are also very important. It doesn't go any good to have a 1/8 wave mirror with significant astigmatism caused by a bad mirror mount.
Mirror cooling is also important, as well as good baffle design (not to mention the consequences of making the tube the wrong length).
I hope this is a joke. You should not even consider using optics with 1000+ wavelength rms error instead of 1/4 wavelength rms error (achievable with a well mounted mirror).
Fresnel lenses are fine for solar furnaces and the like, but not useful in telescopes.
OK, Gore Vidal is an idiot, and I'd pay no more attention to him than I would a Frenchman trying to "educate" me about how the U.S. ought to work
You may disagree with Gore Vidal, but while being quite inflamatory, he is articulate enough in expressing his position that I don't think it is fair to characterize him as an idiot.
More importantly, not being born in the US does not in any way reduce the value of your insights and opinion on the American system. I was born in NZ, and have lived in several other countries since then. I can assure you that I know a lot more about the US constitution and current government than the average native, and seeing how things work in other countries provides additional insight into the best and worst aspects of different governments and forms of government.
I have always believed, and continue to believe that the US is the best country in the world to live in, but lately the margin is getting smaller and smaller (IMHO).
Just wanted to mention that I did my part last week by replacing an SCO system with Linux rather than upgrading SCO to support a modern server. Everyone should consider it their duty to find and replace as many SCO servers as possible with Linux.
The original media and license were sent back to SCO with a "nice" note.
How about printing a ballot with the votes cast in plain text so the voter can audit them. The ballot also contains a unique id that ties the vote to the electronic record (but not the voter). The voter audits the ballot (if they care to), then deposits it on the way out the same way ballots have always been collected.
Election officials can now do random, targeted, partial or complete audits of the election vote count. Since the paper ballots are unambiguous (no chads, etc) recounts can be done via OCR with the ballots (shouldn't be barcode, there is no guarantee that the barcode matches the text the voter audited).
BTW, Windows would be just fine, but would have no clear advantage over Linux in this app (or an embedded OS). And since we are paying for it let MS cough up free licenses for voting as a public service (or use linux, their choice).
Consider the Honda Civic GX. It is a conventional IC engine, but is compressed natural gas (CNG) only (no gasoline). It gets pretty good mileage, and has VERY low emissions without all the complexity of a hybrid.
You can also get CNG conversions for many other cars, vans and trucks.
We have to distinguish between the machines that are to be infected and the machines to be attacked. Most worms target idiot home users of windows who are not smart enough to patch their software. Once the worms reach critical mass, they are often intended to launch DOS attacks against public servers. The targets of the attack are no doubt linux/unix boxes as often as windows boxes.
So, if you wanted to hurt the internet, you would target windows machines to replicate and host the worm, then be os agnostic about your target.
You can take issue with Windows being a problem for the internet (because of its wide spread use by people who don't care about installing patches), but if you can't deploy a windows server in a managed environment and protect it from attacks like Sobig and Blaster, then I doubt you can adequately protect a linux box from the same level of attack (should anyone bother to write such worms/viruses).
You can't whine about not having basic security tools like ipchains, if you have never bothered either blocking ports at the firewall, or turning on TCP/IP filtering in windows (you didn't raise that point, but it is a common argument).
Granted that worms like Code Red were a problem for enterprise environments (mostly due to notebook users bringing things in from outside), but IMHO this was mostly a deployment issue, why are workstation machines deployed with filesharing turned on? Do sysadmin's want users storing authoritative (and usually only) copies of data important enough to require sharing with others on their workstations? Linux is made secure by limiting provided services to a reasonable, necessary list. Windows is no different.
Slammer was a different story. For the life of me, I don't know why MS had to build a UDP based browsing service for SQL Servers. How many environments are there where the sysadmin's don't know the names of the sql servers, or they need users to be browsing around looking for a server? One of microsoft's big problems is not so much the quality of the software they produce, it's the silly bells and whistles they build into every application, then install and enable by default. Where was the option to turn off 1434/udp in SQL Server? Where was I asked to install this non-necessary network service? Why are all the executable file types installed in IIS by default (like IDA, htx, etc)?
Don't just block them, redirect the AOL users to a page that explains the action. AOL is generally so slow and unreliable that users would have no idea that you are blocking access unless you tell them.
So you are saying that the sysadmin's for these systems, who apparently did not properly/completely firewall their systems have no responsibility for this?
If I set up a safety critical system using out-of-the-box Redhat 6 with no firewall restrictions and no patches and get root'ed by SSL exploits, is Redhat 100% responsible for my stupidity? I think not.
It comes down to this, if you are administering a critical system, it must either be completely isolated from the internet and from any other machine that is ever connected to the internet, or you have to keep it patched. Either way, it is only common sense that you firewall the system and only allow access via ports necessary for the operation of the system. Ports necessary for maintenance operations should normally be disabled and only enabled during maintenance operations.
If you don't understand this, you should not be in charge of a mission critical system.
One place I think you can blame MS is their decision not to continue releasing patches for Windows NT 4.0. Many safety critical systems can't just be upgraded to a new operating system on a whim, there is a lot of testing that has to be done. In the current climate, many companies are unwilling to fund these upgrades for a "possible threat". While it costs MS money to build these patches, I suspect the bad PR associated with these events is even more expensive, and maybe (just maybe), it will help entice MS to actually code buffer overflow checks as a standard development practice.
Nope, the OEM distribution you get for 98 up through 2000 is pretty much standard issue windows except that you can't use an OEM install set to upgrade a previous OS version. Serial numbers and activiation keys for OEM media are not interchangable with "retail" versions.
Windows XP is a little different. The OEM install only gets a single activation, but apparently it can be used to upgrade a pervious OS version (I have had success with Win2K and XP Home upgrades). If you change MB's or anything else significant, you have to call MS and beg for a new activation key (which they apparently always supply, it just takes a little time).
I have several, and like the Storix Axis ones the best. They are not cheap, but they are small and, most importantly, there is no cap to lose (the USB cover rotates around to the back when in use).
This is the only one I have that I would actually put on a keychain.
Re:Monster Tech-en developer demand tag team match
on
Essential .NET, Volume I
·
· Score: 2, Funny
Of course, it is also possible that it takes 10 times as many Java developers to get the same job done.
I am suggesting this as a story line, not as real physics, but since we are seeing signs that dark matter/energy exhibits a repulsive force of some kind, how about if dark matter was "neutral matter" that did not react with M or A-M except through it's repulsive force. This could implement the buffer between the M and A-M galaxies and explain the lack of observed annihilation events between the galaxies.
I have a spare dual Pentium-Pro Compaq Proliant (19" rack mount) with a full set of disks and a raid controller, dual nics, redundant power, etc. You can have it with two conditions:
1. Send me a request to ship it on school stationary
2. I ship it to you COD for the shipping
The machine was a server at a charity that upgraded (received a new donation or server hardware). It is fully operational, and comes with a spare hard disk. I can load it with your preferred version of Linux (RH9 is what I would recommend), or I can ship it blank if you want to add your own Windows OS.
This machine will more than meet your needs running linux, and it will meet them under windows as long as you are not using Exchange. Netwin (www.netwinsite.com) has good mail servers for windows and they do deals for schools. They provide webmail, scale really well and are very flexible and easy to administer.
Drop me a response if you want to go ahead with this and I'll send you my address.
Personally, I would make continued employment for the current exec staff (1-2 months should do) a condition of the buy-out. Then I would put the execs to work washing IBM employee cars in the parking lot all day.
Spite is an evil thing, but I think these guys need adjusting.
You didn't say whether you needed 10 watts peak or 10 watts average.
Assuming it is average and you are doing long term measurements, the average data rate must be pretty low (relative to hard disk transfer rates). So, I would add RAM to the sensor end controller and cache information there until you hit lets say 80% cache full, then fire up the hard disk and do the writes.
I would use USB 1.1 for the link, controllers are easy to find and cheap, the power requirements are much lower then ethernet+microcontroller+drive interface.
If your power requirements are peak, then put a lion battery on the hard disk end, charge it from the USB power and operate the drive from that.
If cost it not a huge issue, you might consider 10 2GB compactflash cards. That would eliminate the need to implement the remote data link.
You might want to check into not-for-profit pricing for Microsoft. It's a lot cheaper than OpenExchange and while exchange administration can be a pain, once you know the ropes it's not so bad.
I provide IT services for two charities (30-40 users) and Exchange or SBS with Exchange works out pretty well.
I suspect the big difference is the presence of a clock signal. LCD controllers have to "guess" at where the pixel borders are in the analog signal. The transitions between pixel values are not nice square wave transitions, everything looks a lot more rubbery in reality. The result is an unintended antialiasing of the pixel data (in a 1:1 resolution situation), or with a crappy analog->lcd controller pixel jitter.
With the clocked digital DVI signal, the intended value for each pixel can be determined exactly.
Slashdot Mirror
What you need to do is choose between 802.11B and 802.11G (I'd probably go B for what you have in mind). Purchase the following:
an access point (not a router, an access point)
a pcmcia or usb 802.11b adapter
an omni-directional, high gain antenna for the AP (7-9dbi, slotted waveguide, vertical colinear array, etc)
Install the USB/PCMCIA adapter in a notebook, and start experimenting with access point/antenna locations on each floor. The Access point does not need to be connected to an ethernet drop to test signal strength. Remember that the omni antenna have a horizontal donut shaped radiation pattern, so you need to mount it pretty close to vertical for your tests.
I suspect that you will need 2 AP's per floor, so your cost should look like this (assuming you do all the work):
Internet Connection: ??
8xAccess Points - Dlink DWL-900+: $512 (newegg)
2000' cat 5 pvc cable: $70 (computergate)
16 port switch - DLink DSS16+: $75 (newegg)
Surface mount cat 5 boxes, 3x4 port boxes at switch end, 20 patch cables: $200 (computergate)
Total should be less than $900
The biggest problem you are likely to face is getting power to the Access Points. Power Over Ethernet can be a little bit of a pain to set up if you are now electronically inclined, and building code can be your enemy in terms of running extension cords or additional outlet boxes.
Also remember that there are special code requirements for running any type of cables through a vertical shaft like the elevator shaft. If there is an existing conduit running vertically for phone cabling, that is your best bet.
Also/FYI: my experience is that cheap patch panel antennas are useless. The two I have purchased do not outperform a standard dipole.
Dean
What they should do is write Burt Rutan's group (Scaled Composites) a big check, and set them loose on the problem.
Also, setting up a manned moon base has lots of benefits both as a scientific/industrial asset, as well as a way to get robotic probes out into space without having to get out of the giant sucking gravity hole we live on. Without the stress of earth launch, we would gain significant cost reductions on these missions, as well as a lot of engineering flexibility. With the low launch costs from the moon, we could take a micro-sat / shotgun approach to solar system exploration.
Sending a manned mission to mars appears to only have political benefits at this point, and looks like it is impractical given the economic and safety constraints such a project is likely to operate under.
The fast majority of homebuilt telescopes are built using glass, pyrex or zerodur (all glasses of various compositions) mirrors. All newtonian telescopes f/8 or slower can sometimes be made with spherical mirrors, everything faster than that requires a parabolic mirror.
Many amateurs polish their own mirrors. A great project if you have the time, and a great project if you have kids, but you'd have to be working at a McJob to come close to breaking even on the time vs purchasing a prefab mirror.
Depending on your fabrication skills and facilities, you might also want to look into a truss dobson (probably not necessary at 8"), or a split ring mount. The split ring mount is an equatorial mount, making it easy to add a motor to track objects against the earth's rotation. Even if you want to learn the sky for yourself (rather than use a goto system), tracking is very very useful, particularly when sharing the views with others. The split ring also avoids field-rotation at the eyepiece allowing long exposure astro-photography using film or digital cameras.
I started out with a 10" meade starfinder dob, rebuilt it as a truss scope (goto), then rebuilt it as a split ring (motorized but not goto). The Meade starfinder design is very similar to the one you referenced, and is by far the easiest to build.
Be aware that astronomy is a disease, I don't know anyone who uses a telescope regularly and only owns a single telescope.
Dean
Mirror cooling is also important, as well as good baffle design (not to mention the consequences of making the tube the wrong length).
Fresnel lenses are fine for solar furnaces and the like, but not useful in telescopes.
There are forums there you might ask about lab admin as well.
You may disagree with Gore Vidal, but while being quite inflamatory, he is articulate enough in expressing his position that I don't think it is fair to characterize him as an idiot.
More importantly, not being born in the US does not in any way reduce the value of your insights and opinion on the American system. I was born in NZ, and have lived in several other countries since then. I can assure you that I know a lot more about the US constitution and current government than the average native, and seeing how things work in other countries provides additional insight into the best and worst aspects of different governments and forms of government.
I have always believed, and continue to believe that the US is the best country in the world to live in, but lately the margin is getting smaller and smaller (IMHO).
The original media and license were sent back to SCO with a "nice" note.
Election officials can now do random, targeted, partial or complete audits of the election vote count. Since the paper ballots are unambiguous (no chads, etc) recounts can be done via OCR with the ballots (shouldn't be barcode, there is no guarantee that the barcode matches the text the voter audited).
BTW, Windows would be just fine, but would have no clear advantage over Linux in this app (or an embedded OS). And since we are paying for it let MS cough up free licenses for voting as a public service (or use linux, their choice).
You can also get CNG conversions for many other cars, vans and trucks.
So, if you wanted to hurt the internet, you would target windows machines to replicate and host the worm, then be os agnostic about your target.
You can't whine about not having basic security tools like ipchains, if you have never bothered either blocking ports at the firewall, or turning on TCP/IP filtering in windows (you didn't raise that point, but it is a common argument).
Granted that worms like Code Red were a problem for enterprise environments (mostly due to notebook users bringing things in from outside), but IMHO this was mostly a deployment issue, why are workstation machines deployed with filesharing turned on? Do sysadmin's want users storing authoritative (and usually only) copies of data important enough to require sharing with others on their workstations? Linux is made secure by limiting provided services to a reasonable, necessary list. Windows is no different.
Slammer was a different story. For the life of me, I don't know why MS had to build a UDP based browsing service for SQL Servers. How many environments are there where the sysadmin's don't know the names of the sql servers, or they need users to be browsing around looking for a server? One of microsoft's big problems is not so much the quality of the software they produce, it's the silly bells and whistles they build into every application, then install and enable by default. Where was the option to turn off 1434/udp in SQL Server? Where was I asked to install this non-necessary network service? Why are all the executable file types installed in IIS by default (like IDA, htx, etc)?
Don't just block them, redirect the AOL users to a page that explains the action. AOL is generally so slow and unreliable that users would have no idea that you are blocking access unless you tell them.
If I set up a safety critical system using out-of-the-box Redhat 6 with no firewall restrictions and no patches and get root'ed by SSL exploits, is Redhat 100% responsible for my stupidity? I think not.
It comes down to this, if you are administering a critical system, it must either be completely isolated from the internet and from any other machine that is ever connected to the internet, or you have to keep it patched. Either way, it is only common sense that you firewall the system and only allow access via ports necessary for the operation of the system. Ports necessary for maintenance operations should normally be disabled and only enabled during maintenance operations.
If you don't understand this, you should not be in charge of a mission critical system.
One place I think you can blame MS is their decision not to continue releasing patches for Windows NT 4.0. Many safety critical systems can't just be upgraded to a new operating system on a whim, there is a lot of testing that has to be done. In the current climate, many companies are unwilling to fund these upgrades for a "possible threat". While it costs MS money to build these patches, I suspect the bad PR associated with these events is even more expensive, and maybe (just maybe), it will help entice MS to actually code buffer overflow checks as a standard development practice.
Also be aware that these things are not even close to being "low power", if you are looking to operate under battery power I'd look elsewhere.
Windows XP is a little different. The OEM install only gets a single activation, but apparently it can be used to upgrade a pervious OS version (I have had success with Win2K and XP Home upgrades). If you change MB's or anything else significant, you have to call MS and beg for a new activation key (which they apparently always supply, it just takes a little time).
This is the only one I have that I would actually put on a keychain.
Just kidding...
Just an idea...
1. Send me a request to ship it on school stationary
2. I ship it to you COD for the shipping
The machine was a server at a charity that upgraded (received a new donation or server hardware). It is fully operational, and comes with a spare hard disk. I can load it with your preferred version of Linux (RH9 is what I would recommend), or I can ship it blank if you want to add your own Windows OS.
This machine will more than meet your needs running linux, and it will meet them under windows as long as you are not using Exchange. Netwin (www.netwinsite.com) has good mail servers for windows and they do deals for schools. They provide webmail, scale really well and are very flexible and easy to administer.
Drop me a response if you want to go ahead with this and I'll send you my address.
Dean
CC via email
Spite is an evil thing, but I think these guys need adjusting.
Assuming it is average and you are doing long term measurements, the average data rate must be pretty low (relative to hard disk transfer rates). So, I would add RAM to the sensor end controller and cache information there until you hit lets say 80% cache full, then fire up the hard disk and do the writes.
I would use USB 1.1 for the link, controllers are easy to find and cheap, the power requirements are much lower then ethernet+microcontroller+drive interface.
If your power requirements are peak, then put a lion battery on the hard disk end, charge it from the USB power and operate the drive from that.
If cost it not a huge issue, you might consider 10 2GB compactflash cards. That would eliminate the need to implement the remote data link.
I provide IT services for two charities (30-40 users) and Exchange or SBS with Exchange works out pretty well.
With the clocked digital DVI signal, the intended value for each pixel can be determined exactly.