Since I'm part of this process at a public university, and I happen to think our group does it conscientiously... The devil is in the details. You need to have good requirements, which include reliability, quality and other such variables in quantifiable ways. For example, in our case we mandate five years of NBD advance replacement for equipment and technical support. How that's accomplished, whether as part of warranty, as support contracts that are bundled in etc. is the vendor's problem. Once you have good and proper requirements, you have to test the equipment that vendors hawk to see if it actually does what they claim it does before you sign the contract. Finally, all of this has to be monitored long term for any problems in the agreements, and to update the technology requirements. It's a lot of work, but considering the cost savings to the tax payer and students it's a no-brainer good thing to do. Oddly, doing technology bids properly doesn't add much red tape beyond that already involved in purchasing in our environment. However, none of this works unless you have technically competent and motivated people writing the original requirements and doing the pre-sales testing, and honest management to facilitate the whole thing.
Multicast works just peachy over IPv4, and has for a long, long time. That's how we distribute much of our streaming media on campus and over Internet2. Also, many interior routing protocols such as OSPF use multicast, as do various other systems management protocols/tools. Why ISPs like aren't using it for video and radio delivery is beyond me.
Actually, the preferred way for a website to default to a language should be based on the browser indicated preference. That way, say, French speaking Canadians or Spanish speaking American's don't get lumped in the wrong group based on GeoIP (and I can put in Finnish as my preference regardless of my current location.) The list of preferred languages and their order should be hidden in your browser menu somewhere.
...and according to the specs, they only work on 2.4 GHz and only support WEP. That's right along the lines of what I had found myself, and mirrors the original poster's question on why the offered ip cams have gotten stuck in the technology era of half a decade ago. Also, 640x480 is hardly great.
One more for Tomato. After having tried to figure out the versions, caveats, install and configuration of DD-WRT, Tomato was wonderfully simple and polished. Clear documentation, good GUI, and it just works.
I'm not sure what state-wide regulation there is (although there's talk about crafting some) but where I live in Florida the yellows get lengthened when cameras are put in, and if you get tagged a sheriff's deputy will review the picture and video, and if they deem that the infraction was, in fact, ticket-worthy, you get a link to not only the picture but the accompanying video snippet to see exactly what happened, and a chance to contest the ticket (or pay it.) While I would rather get more police on the street to enforce laws than put automated surveillance equipment in more places, it does seem like a pretty well thought-out and fair system to me. (And one of those options needs to happen, because people keep blowing through red lights like there's no tomorrow.)
Nope. Depending on the fiber, there are all manner of dispersion effects at the minimum that distort the signal and lose information. Hence Modal Bandwidth for modal dispersion in multimode fibers, measured in MHz / km, that explains what kind of bandwidth (in the analog, original sense) per distance the fiber is capable of transporting. Belden has a good brief on it: http://www.belden.com/pdfs/TechInfo/TechBandwidth.htm. In practical terms, these distortion effects severely limit multimode fibers -- the real capability of the fiber is much higher than the cheap optics can realize, but it demonstrates that there distortion limits. Adding different colors (DWDM) and smarter waveforms and all such stuff can help, but at the end of the day you're limited; the bigger your fiber is, the longer it is, the less information you can push through it. Singlemode fiber doesn't suffer from modal dispersion, but it has its own issues (different frequencies travel at different speed and interact with each other, basically.)
The parent means Xirrus will cause the event organizers to mortgage a house. Still, Xirrus can have tons of radios in one device, all with segmented antennas, and they really are a good fit for this kind of stuff. They even have a pole/tripod mounting option where you can set up more if need be. See about the sponsoring or maybe renting. Alternatively, get external 60 degree segment antennas for something like Cisco 1250s and do hexagonal cells, like wireless carriers do. For dual band MIMO you need six antennas per AP, so it'll get out of control mighty fast. Worst case, get a bunch of APs, have three of them use the three 2.4 GHz channels with MIMO (but no channel bonding!) and as many 5 GHz ones as you can, since you have many more non-overlapping channels to work with. Chances are that anyone stuck on 2.4 GHz is going to hate life. Plan power levels as well, and don't run radios hotter than they need to be, despite the temptation. Also, very, very important: DISABLE LOW DATA RATES. Mandate 5 or 11 Mbps as the lowest supported rate at all the radios. Otherwise the 1 Mbps Nintendo DS's and phones will eat up all the airtime and starve everyone of access. If you can get away with turning off 802.11b support and only offering 802.11g on 2.4 GHz, do so. Finally, ignore any comment suggesting consumer gear.
Well, not necessarily in a patch panel, but on the office side where the cable gets moved on a daily basis, kicked around etc. We've certainly seen solid conductors snap after enough flexing. (Then again, when you roll chairs and filing cabinets over patch cords, they all get demolished sooner or later;-) )
My employer did stock both, when we still did patch cables in house.
Solid is for horizontal runs (within walls), stranded is for patch cords that will be flexed, such as between a jack and a user's computer. As it's always been.
Correct; I should've been clearer -- I meant the situation when a non-ham is using the 2.4 Ghz unlicensed band. I run into this at work where, when you follow Cisco guidelines on allowed unlicensed Wifi power levels for their parabolic antennas, you have to reduce AP output into a fraction of the power allowed into an lower gain antenna.
...and once transmitting at more than 50W, HAMs must conduct a station evaluation to make sure no excessive fields pose a hazard to humans or animals, according to FCC rules. Also, see http://www.fcc.gov/oet/rfsafety/rf-faqs.html. When considering these antennae, also consider that they are likely to be very high duty cycle and directional (rather than omnidirectional) which increases the radiation density. When using directional antennae with 2.4 GHz Wifi, you're limited to tens of milliwatts or even less, depending on the gain. Sum: I'd worry.
Well, as long as a given cell phone tower depends on central registries of handsets and SIMs for billing, authorization and coordination between cell sites, you must not only have the backhaul between cells, but also connectivity to server farms and control systems. If you have that, fine, but if fiber is cut and the operator's data center is fubar, getting the cell network up will take a few days. Obviously 2-way radio is very capacity limited, relies on verbal communication (packet HAM radio aside), and is a broadcast medium which limits its uses, but I maintain that because of its simplicity we'll see it being deployed for a while more. What would be interesting as a replacement are the Tetra-style European emcomm systems which you can theoretically get up and running by just parking a few equipped police cruisers strategically, and they offer text messaging, data and encrypted communications.
Yes, yes we do. Satellite capacity is limited, and requires fairly expensive and advanced handsets. Good for important, long range communications. Putting up an FM / UHF repeater to serve a bunch of metropolitan two-way analog radios, or an HF antenna to serve long-range analog communications is simple, cheap, cost effective and with prepared hams a matter of hours, if not less. They've repeatedly proven to be useful after emergencies when no official communications capability has existed, or what exists has been overwhelmed.
Not sure what your expectations are, or what the policy of your school is, but in any sort of litigation or suspicion of academic malfeasance, or even internal disputes within departments it's been my experience that just as in most corporations your university email is fair game and not covered by anything like the protections of third-party email or regular mail.
When I was grading programming homework a decade or two ago (theoretical physics, oddly enough) it was obvious when people shared their code. The use of spaces, indentation, variable names, curly braces etc. really made each assignment unique, and the people who resorted in copying someone's code almost never bothered to make any changes at all. My solution was to give the first assignment turned in whatever grade it deserved, and each subsequent copy a 0, and that seemed to make short work of the practice. At my current university the response would be significantly harsher.
Using IP multicast only the streams that have subscribers in a given cell get streamed to that cell, and then within the cell get distributed to subscribers. QoS should be fairly trivial as the multicast stream is obviously streaming TV content. If reserved bandwidth is needed, policing can be done preventing excess users from subscribing to a stream. Trying to mimic circuit-switched reserved bandwidth chunks over a natively packet based media always strikes me as silly.
Whatever happened to IP multicast? Quite well suited for TV streaming across any number of platforms, and as a transport layer it doesn't get much more universally standardized and accepted than that.
Considering how little attention people seem to pay to the "buckle up and sit down" sign, I'm curious to see how many people decide to go to the loo anyways, or get stuff from their carry-on, or wander around to talk to their girlfriends. Regardless, I hope these rules remain temporary, like the total ban on liquids that was in force for a while.
Slashdot Mirror
Since I'm part of this process at a public university, and I happen to think our group does it conscientiously... The devil is in the details. You need to have good requirements, which include reliability, quality and other such variables in quantifiable ways. For example, in our case we mandate five years of NBD advance replacement for equipment and technical support. How that's accomplished, whether as part of warranty, as support contracts that are bundled in etc. is the vendor's problem. Once you have good and proper requirements, you have to test the equipment that vendors hawk to see if it actually does what they claim it does before you sign the contract. Finally, all of this has to be monitored long term for any problems in the agreements, and to update the technology requirements. It's a lot of work, but considering the cost savings to the tax payer and students it's a no-brainer good thing to do. Oddly, doing technology bids properly doesn't add much red tape beyond that already involved in purchasing in our environment. However, none of this works unless you have technically competent and motivated people writing the original requirements and doing the pre-sales testing, and honest management to facilitate the whole thing.
Or you can make a tidy profit by buying 200 of them and selling them for cash anonymously at the local gun show.
I was wondering if I was the only one the slasdot posting struck as straight ad copy, for a product that's not particularly new, unique or cheap.
Multicast works just peachy over IPv4, and has for a long, long time. That's how we distribute much of our streaming media on campus and over Internet2. Also, many interior routing protocols such as OSPF use multicast, as do various other systems management protocols/tools.
Why ISPs like aren't using it for video and radio delivery is beyond me.
Actually, the preferred way for a website to default to a language should be based on the browser indicated preference. That way, say, French speaking Canadians or Spanish speaking American's don't get lumped in the wrong group based on GeoIP (and I can put in Finnish as my preference regardless of my current location.) The list of preferred languages and their order should be hidden in your browser menu somewhere.
No argument about Apple's site, though :-)
...and according to the specs, they only work on 2.4 GHz and only support WEP. That's right along the lines of what I had found myself, and mirrors the original poster's question on why the offered ip cams have gotten stuck in the technology era of half a decade ago. Also, 640x480 is hardly great.
One more for Tomato. After having tried to figure out the versions, caveats, install and configuration of DD-WRT, Tomato was wonderfully simple and polished. Clear documentation, good GUI, and it just works.
And how much of this had to do with NAT rules rather than firewalls?
I'm not sure what state-wide regulation there is (although there's talk about crafting some) but where I live in Florida the yellows get lengthened when cameras are put in, and if you get tagged a sheriff's deputy will review the picture and video, and if they deem that the infraction was, in fact, ticket-worthy, you get a link to not only the picture but the accompanying video snippet to see exactly what happened, and a chance to contest the ticket (or pay it.) While I would rather get more police on the street to enforce laws than put automated surveillance equipment in more places, it does seem like a pretty well thought-out and fair system to me. (And one of those options needs to happen, because people keep blowing through red lights like there's no tomorrow.)
Nope. Depending on the fiber, there are all manner of dispersion effects at the minimum that distort the signal and lose information. Hence Modal Bandwidth for modal dispersion in multimode fibers, measured in MHz / km, that explains what kind of bandwidth (in the analog, original sense) per distance the fiber is capable of transporting. Belden has a good brief on it: http://www.belden.com/pdfs/TechInfo/TechBandwidth.htm.
In practical terms, these distortion effects severely limit multimode fibers -- the real capability of the fiber is much higher than the cheap optics can realize, but it demonstrates that there distortion limits. Adding different colors (DWDM) and smarter waveforms and all such stuff can help, but at the end of the day you're limited; the bigger your fiber is, the longer it is, the less information you can push through it.
Singlemode fiber doesn't suffer from modal dispersion, but it has its own issues (different frequencies travel at different speed and interact with each other, basically.)
The parent means Xirrus will cause the event organizers to mortgage a house. Still, Xirrus can have tons of radios in one device, all with segmented antennas, and they really are a good fit for this kind of stuff. They even have a pole/tripod mounting option where you can set up more if need be. See about the sponsoring or maybe renting.
Alternatively, get external 60 degree segment antennas for something like Cisco 1250s and do hexagonal cells, like wireless carriers do. For dual band MIMO you need six antennas per AP, so it'll get out of control mighty fast.
Worst case, get a bunch of APs, have three of them use the three 2.4 GHz channels with MIMO (but no channel bonding!) and as many 5 GHz ones as you can, since you have many more non-overlapping channels to work with. Chances are that anyone stuck on 2.4 GHz is going to hate life. Plan power levels as well, and don't run radios hotter than they need to be, despite the temptation.
Also, very, very important: DISABLE LOW DATA RATES. Mandate 5 or 11 Mbps as the lowest supported rate at all the radios. Otherwise the 1 Mbps Nintendo DS's and phones will eat up all the airtime and starve everyone of access. If you can get away with turning off 802.11b support and only offering 802.11g on 2.4 GHz, do so.
Finally, ignore any comment suggesting consumer gear.
Well, not necessarily in a patch panel, but on the office side where the cable gets moved on a daily basis, kicked around etc. We've certainly seen solid conductors snap after enough flexing. (Then again, when you roll chairs and filing cabinets over patch cords, they all get demolished sooner or later ;-) )
My employer did stock both, when we still did patch cables in house.
Solid is for horizontal runs (within walls), stranded is for patch cords that will be flexed, such as between a jack and a user's computer. As it's always been.
Correct; I should've been clearer -- I meant the situation when a non-ham is using the 2.4 Ghz unlicensed band. I run into this at work where, when you follow Cisco guidelines on allowed unlicensed Wifi power levels for their parabolic antennas, you have to reduce AP output into a fraction of the power allowed into an lower gain antenna.
...and once transmitting at more than 50W, HAMs must conduct a station evaluation to make sure no excessive fields pose a hazard to humans or animals, according to FCC rules. Also, see http://www.fcc.gov/oet/rfsafety/rf-faqs.html. When considering these antennae, also consider that they are likely to be very high duty cycle and directional (rather than omnidirectional) which increases the radiation density. When using directional antennae with 2.4 GHz Wifi, you're limited to tens of milliwatts or even less, depending on the gain. Sum: I'd worry.
Well, as long as a given cell phone tower depends on central registries of handsets and SIMs for billing, authorization and coordination between cell sites, you must not only have the backhaul between cells, but also connectivity to server farms and control systems. If you have that, fine, but if fiber is cut and the operator's data center is fubar, getting the cell network up will take a few days.
Obviously 2-way radio is very capacity limited, relies on verbal communication (packet HAM radio aside), and is a broadcast medium which limits its uses, but I maintain that because of its simplicity we'll see it being deployed for a while more.
What would be interesting as a replacement are the Tetra-style European emcomm systems which you can theoretically get up and running by just parking a few equipped police cruisers strategically, and they offer text messaging, data and encrypted communications.
Yes, yes we do. Satellite capacity is limited, and requires fairly expensive and advanced handsets. Good for important, long range communications. Putting up an FM / UHF repeater to serve a bunch of metropolitan two-way analog radios, or an HF antenna to serve long-range analog communications is simple, cheap, cost effective and with prepared hams a matter of hours, if not less. They've repeatedly proven to be useful after emergencies when no official communications capability has existed, or what exists has been overwhelmed.
Check out the titanium manganese batteries Citizen uses in their eco-drive. They're supposed to last for decades while being charged and discharged.
Not sure what your expectations are, or what the policy of your school is, but in any sort of litigation or suspicion of academic malfeasance, or even internal disputes within departments it's been my experience that just as in most corporations your university email is fair game and not covered by anything like the protections of third-party email or regular mail.
Besides, how many ways can you write a QuickSort?
When I was grading programming homework a decade or two ago (theoretical physics, oddly enough) it was obvious when people shared their code. The use of spaces, indentation, variable names, curly braces etc. really made each assignment unique, and the people who resorted in copying someone's code almost never bothered to make any changes at all. My solution was to give the first assignment turned in whatever grade it deserved, and each subsequent copy a 0, and that seemed to make short work of the practice. At my current university the response would be significantly harsher.
Using IP multicast only the streams that have subscribers in a given cell get streamed to that cell, and then within the cell get distributed to subscribers. QoS should be fairly trivial as the multicast stream is obviously streaming TV content. If reserved bandwidth is needed, policing can be done preventing excess users from subscribing to a stream. Trying to mimic circuit-switched reserved bandwidth chunks over a natively packet based media always strikes me as silly.
Whatever happened to IP multicast? Quite well suited for TV streaming across any number of platforms, and as a transport layer it doesn't get much more universally standardized and accepted than that.
Considering how little attention people seem to pay to the "buckle up and sit down" sign, I'm curious to see how many people decide to go to the loo anyways, or get stuff from their carry-on, or wander around to talk to their girlfriends. Regardless, I hope these rules remain temporary, like the total ban on liquids that was in force for a while.
BBC claims this Joe Six-Pack was Dutch, actually.
Any more news on the new offer Spyker just made for the Saab assets? Not guaranteed to be dead yet.