I installed a DIY solar water heating system on my house. It's a two-tank system. The solar system heats water in a 120 gal storage tank, which then feeds into a standard 40 gal gas water heater. During the summer, the solar system does all the work, and the gas heater never fires up. In the winter, the solar system gets the water up to about 90 degrees, and the gas heater does the rest of the work.
I estimate the solar system saves us almost $400/year at current gas rates.
If you get a VoIP adapter and provider that support T.38, you'll have much better luck with faxing over VoIP. As I understand it, T.38 allows your VoIP adapter to emulate G3 fax audio signals of the remote fax machine, and conversely, your service provider emulates your fax machine at the interface with the PSTN.
I use a Linksys SPA-2102 VoIP ATA with Gafachi as my service provider, both of which support T.38. I can report that I haven't had a single problem sending or receiving a fax.
I once interviewed with a group in San Francisco that did stuff like this. They weren't clear about who they were working for, but I do remember some of the techniques they mentioned during the interview. Some of these were actually implemented, others were just ideas:
- An eBay crawler that could estimate the number of auctions and average selling price to predict whether eBay would make their earnings target or not. eBay quickly blacklisted their IP space, so they started using a bunch of open proxies they found.
- By analyzing client/server communication for the Sims Online, they discovered that each connection was assigned a sequentially incrementing connection ID number. By looking at the rate at which the connection ID numbers were increasing each time they logged in, they determined that the Sims Online wasn't going to be nearly as popular as Electronic Arts was forecasting.
- They talked about placing a camera somewhere in Union Square (in SF) to monitor the entrace to Tiffany's during the holiday shopping season, and doing image analysis to determine what percentage of shoppers left the store with a Tiffany's bag in hand.
- Monitoring wireless carriers' spectrum to determine what percentage of GSM/CDMA channels were in use for data vs. voice. The communication itself is encrypted of course, but you can still tell whether a channel is carrying voice or data. They wanted to determine if wireless carriers forecasts about revenue from data services were accurate.
I just returned from a trip to Norway and Svalbard. Just for fun, I pulled up Slashdot on my Treo 600. Surprisingly, both Telenor and Norway NetCom had very good GSM/GPRS coverage in and around Longyearbyen (the main city on Svalbard, pop. ~1500). I think this is probably the northernmost GSM service area in the world, at 78 degrees north.
I think it's been mentioned here on slashdot before, but broadband-over-powerline systems have many drawbacks. Because power lines are not shielded, they will act as very effective radiating antennas for the signals they carry. Many of the proposed broadband systems utilize frequency ranges that overlap military, emergency, commercial and amateur radio bands, with the potential to cause a great deal of harmful interference to users of those services. Many countries, including Japan, the UK, and the Netherlands have already rejected broadband-over-powerline technology for this reason. Check out this page for more info: http://www.arrl.org/tis/info/HTML/plc/
Right around the $900 mark I think. I had intended to keep a really accurate account of that, but I've misplaced some of the receipts now. I also resold some of the hardware that didn't work out on eBay.
> At the beginning you said that you would call > the FAA NOTAM when you were going to make the > launch, did you make that call? If so what did > they say?:)
I did call them. I told them I was launching a weather balloon. They asked, basically, when, where, how big, what's your name? Once I'd answered those questions, they said, "Okay, thanks." and that was it:)
Here in San Francisco, we have a wonderful resource at Craigslist. I'm sure most slashdotters (especially those in the bay area) have heard of it. I believe they've added some Craiglists for other metro areas as well.
I wouldn't claim to be a Craigslist history expert, but I believe the site started off as a free classified ads site (mostly appartments for rent). Just the classifieds alone have created
a one-stop meeting place for finding just about
anything you need -- I've found both of last two places I've lived there, bought a Vespa, bought and sold a couch, etc, etc.
And now with the addition of forums and real-life Craigslist get-togethers, I would argue that Craigslist is turning into a true on-line community.
In rural areas, Internet connectivity options are going to be pretty limited, unless the the specific sites and dates for visits are known months in advance. Even then it could be pretty hard. I think satellite-type connectivity options might be your only choice. You might want to check out these guys:
DirecPC --
http://www.direcpc.com/
Starband --
http://www.starband.com/
OnSat --
http://www.onsat.net/
Although you can no longer get to it from the main web site (which has been replaced with a bankruptcy notice), the coverage maps are still available.
I believe Metricom also built infrastructure in some additional metro areas where service was never officially announced and no coverage maps are available, but Aerie has the rights to that equipment as well. Some of those metros include Chicago and Salt Lake City.
Indeed, upon further research, we're already way beyond 80 Gbps on a single fiber. DWDM (dense wave division multiplexing) can increase the capacity of a single fiber to 1.6 Tbps, and soon to 3.2 Tbps with 80 wavelengths at OC-768 according to this press release from NEC. As the press release states, a 3.2 Tbps data rate is the equivalent of transmitting 1600 feature-length films every second.
I don't understand the importance of this discovery. I'm pretty sure existing DWDM systems can put at least 16 wavelengths on a single fiber at OC-192 (10 Gbps) speeds for a total capacity of 160 Gbps...
We did this at an ISP that I worked at previously. Bought a DSLAM and some CPE modems from Paradyne and started ordering alarm circuits from Ameritech. The Paradyne gear was pretty good, giving 768 Kbps full duplex if the line was really clean and automatically adjusting the bit rate downward if the line was not as clean. We could get synch between the DSLAM and the modem over as much as 18Kft of copper.
As Cringely described, Ameritech told us a lot of things about why we couldn't have alarm circuits, including the fact that alarm circuits weren't tariffed to carry data. We eventually discovered that there are a lot of places to order telco services from however. We had a lot of success faxing orders directly to Ameritech's order processing center, and we were also able to order through authorized Ameritech resellers without any problems. I'm assuming most of the other ILECs also have order processing centers and authorized resellers.
The biggest problem is that about half of the circuits Ameritech installed for us, especially the longer ones, would have load coils on them. These are on most longer copper runs to even out the change the impedance so the all of the lines coming into the switch look about the same. Unfortunately, nearly all data gear fails to operate over lines with load coils, and Ameritech wouldn't or couldn't tell us if a line had coil or not until it was installed. And of course they wouldn't remove the coil after it had been installed, because if we were really using it as an alarm circuit, there'd be no reason to.
Northwestern did this right from the beginning I think. Starting from the first year the dorms were networked, the university corralled a group of ResCons (short for Residential Networking Consultants) who received certain perks, including housing in their dorm and even room of choice. Then they hired a smaller group of Sr. ResCons (also students) to manage the volunteers. There was a week-long training session for the ResCons before school started. The program was very successful, and it actually became quite competitive. There were many more applicants for ResCons that positions available. Of course, some residences (i.e sororities) were typically hard to staff, but in general, a very successful approach.
Slashdot Mirror
I installed a DIY solar water heating system on my house. It's a two-tank system. The solar system heats water in a 120 gal storage tank, which then feeds into a standard 40 gal gas water heater. During the summer, the solar system does all the work, and the gas heater never fires up. In the winter, the solar system gets the water up to about 90 degrees, and the gas heater does the rest of the work.
I estimate the solar system saves us almost $400/year at current gas rates.
Does this affect on-line used CD trading sites like lala.com and swapacd.com?
If you get a VoIP adapter and provider that support T.38, you'll have much better luck with faxing over VoIP. As I understand it, T.38 allows your VoIP adapter to emulate G3 fax audio signals of the remote fax machine, and conversely, your service provider emulates your fax machine at the interface with the PSTN.
I use a Linksys SPA-2102 VoIP ATA with Gafachi as my service provider, both of which support T.38. I can report that I haven't had a single problem sending or receiving a fax.
http://www.sensaphone.com/
I once interviewed with a group in San Francisco that did stuff like this. They weren't clear about who they were working for, but I do remember some of the techniques they mentioned during the interview. Some of these were actually implemented, others were just ideas:
- An eBay crawler that could estimate the number of auctions and average selling price to predict whether eBay would make their earnings target or not. eBay quickly blacklisted their IP space, so they started using a bunch of open proxies they found.
- By analyzing client/server communication for the Sims Online, they discovered that each connection was assigned a sequentially incrementing connection ID number. By looking at the rate at which the connection ID numbers were increasing each time they logged in, they determined that the Sims Online wasn't going to be nearly as popular as Electronic Arts was forecasting.
- They talked about placing a camera somewhere in Union Square (in SF) to monitor the entrace to Tiffany's during the holiday shopping season, and doing image analysis to determine what percentage of shoppers left the store with a Tiffany's bag in hand.
- Monitoring wireless carriers' spectrum to determine what percentage of GSM/CDMA channels were in use for data vs. voice. The communication itself is encrypted of course, but you can still tell whether a channel is carrying voice or data. They wanted to determine if wireless carriers forecasts about revenue from data services were accurate.
Yep, same with the elevators in the big office tower at 120 Kearny (aka One Montgomery) in San Francisco. They have also been there a while.
I just returned from a trip to Norway and Svalbard.
Just for fun, I pulled up Slashdot on my Treo 600.
Surprisingly, both Telenor and Norway NetCom had very good GSM/GPRS coverage in and around Longyearbyen (the main city on Svalbard, pop. ~1500). I think this is probably the northernmost GSM service area in the world, at 78 degrees north.
-j
I think it's been mentioned here on slashdot before, but broadband-over-powerline systems have many drawbacks. Because power lines are not shielded, they will act as very effective radiating antennas for the signals they carry. Many of the proposed broadband systems utilize frequency ranges that overlap military, emergency, commercial and amateur radio bands, with the potential to cause a great deal of harmful interference to users of those services. Many countries, including Japan, the UK, and the Netherlands have already rejected broadband-over-powerline technology for this reason. Check out this page for more info:
http://www.arrl.org/tis/info/HTML/plc/
> What was the total cost of the project?
:)
:)
Right around the $900 mark I think. I had intended to keep a really accurate account of that, but I've misplaced some of the receipts now. I also resold some of the hardware that didn't work out on eBay.
> At the beginning you said that you would call
> the FAA NOTAM when you were going to make the
> launch, did you make that call? If so what did
> they say?
I did call them. I told them I was launching a
weather balloon. They asked, basically, when,
where, how big, what's your name? Once I'd
answered those questions, they said, "Okay,
thanks." and that was it
The PIII-450 is actually handling the load quite well now. I disabled the photo gallery and pointed the photo links directly to the static content.
Load average is less than 1 now.
I don't know what the hit rate and bandwidth utilization is like, but I'll do some Apache log analysis later and find out.
I actually thought this machine would be more up to the task. It's a PIII-450 with plenty of bandwidth.
:)
I think it's the Perl CGI that runs the photo gallery that's killing it.
For the curious, the load average on the machine
is currently about 40
Here in San Francisco, we have a wonderful resource at Craigslist. I'm sure most slashdotters (especially those in the bay area) have heard of it. I believe they've added some Craiglists for other metro areas as well. I wouldn't claim to be a Craigslist history expert, but I believe the site started off as a free classified ads site (mostly appartments for rent). Just the classifieds alone have created a one-stop meeting place for finding just about anything you need -- I've found both of last two places I've lived there, bought a Vespa, bought and sold a couch, etc, etc. And now with the addition of forums and real-life Craigslist get-togethers, I would argue that Craigslist is turning into a true on-line community.
In rural areas, Internet connectivity options are going to be pretty limited, unless the the specific sites and dates for visits are known months in advance. Even then it could be pretty hard. I think satellite-type connectivity options might be your only choice. You might want to check out these guys: DirecPC -- http://www.direcpc.com/ Starband -- http://www.starband.com/ OnSat -- http://www.onsat.net/
Although you can no longer get to it from the main web site (which has been replaced with a bankruptcy notice), the coverage maps are still available. I believe Metricom also built infrastructure in some additional metro areas where service was never officially announced and no coverage maps are available, but Aerie has the rights to that equipment as well. Some of those metros include Chicago and Salt Lake City.
Indeed, upon further research, we're already way beyond 80 Gbps on a single fiber. DWDM (dense wave division multiplexing) can increase the capacity of a single fiber to 1.6 Tbps, and soon to 3.2 Tbps with 80 wavelengths at OC-768 according to this press release from NEC. As the press release states, a 3.2 Tbps data rate is the equivalent of transmitting 1600 feature-length films every second.
I don't understand the importance of this discovery. I'm pretty sure existing DWDM systems can put at least 16 wavelengths on a single fiber at OC-192 (10 Gbps) speeds for a total capacity of 160 Gbps...
We did this at an ISP that I worked at previously. Bought a DSLAM and some CPE modems from Paradyne and started ordering alarm circuits from Ameritech. The Paradyne gear was pretty good, giving 768 Kbps full duplex if the line was really clean and automatically adjusting the bit rate downward if the line was not as clean. We could get synch between the DSLAM and the modem over as much as 18Kft of copper.
As Cringely described, Ameritech told us a lot of things about why we couldn't have alarm circuits, including the fact that alarm circuits weren't tariffed to carry data. We eventually discovered that there are a lot of places to order telco services from however. We had a lot of success faxing orders directly to Ameritech's order processing center, and we were also able to order through authorized Ameritech resellers without any problems. I'm assuming most of the other ILECs also have order processing centers and authorized resellers.
The biggest problem is that about half of the circuits Ameritech installed for us, especially the longer ones, would have load coils on them. These are on most longer copper runs to even out the change the impedance so the all of the lines coming into the switch look about the same. Unfortunately, nearly all data gear fails to operate over lines with load coils, and Ameritech wouldn't or couldn't tell us if a line had coil or not until it was installed. And of course they wouldn't remove the coil after it had been installed, because if we were really using it as an alarm circuit, there'd be no reason to.
Northwestern did this right from the beginning I think. Starting from the first year the dorms were networked, the university corralled a group of ResCons (short for Residential Networking Consultants) who received certain perks, including housing in their dorm and even room of choice. Then they hired a smaller group of Sr. ResCons (also students) to manage the volunteers. There was a week-long training session for the ResCons before school started. The program was very successful, and it actually became quite competitive. There were many more applicants for ResCons that positions available. Of course, some residences (i.e sororities) were typically hard to staff, but in general, a very successful approach.