Summary: Build at least one long-haul link to bridge two meshes. Planning meeting: Thu Mar 3 2011 after the bike maintenance class (done) Planning meeting \#2: Wed Mar 16 2011 after the elements of computing class (doneish) **Sprint Date: Fri-Sun March 25-27** [Inventory](Byzantium_Sprint_2_Inventory "wikilink") ### Schedule FRI: 8:00pm Pizza, sprint 1 recap, and prep (mostly ripping thing apart and some assembly) SAT: - Noon Brunch and final assembly followed by bench tests and midrange tests depending on speed of success - Dinner Time: Dinner outside the space. This must occur outside the space. - 9:00pmish? Discussion and general planning for Sunday optionally followed by more testing/making SUN: - Noon Brunch prep for long distance tests followed by long distance tests - Dinner Time: Dinner outside the space. This must occur outside the space. - 9:00pmish? Discussion and planning for the next sprint ### Stuff to bring (proposed) - FMRS/GMRS radios that you wouldn't mind hacking. - Childrens' walkie-talkies. [User:Drwho](User:Drwho "wikilink") knows where to buy cheap pairs of them locally. - Webcams *that are known to work with Linux*. That's closer to black magick than computer science, so do your homework first (or on your smartphone while at the store). The feature to look for is called [UVC](http://en.wikipedia.org/wiki/USB_video_device_class) though webcam boxes still might not mention it. - Laser pointers (the more exotic the colors the better). Buy them when you find them. When you go looking for them you can never find them. - Really bright LEDs - Photocells, photoresistors, photodetectors. - Microcontrollers. They may come in handy for modulating/demodulating signals. - Hackable wireless access points. Here are some [examples](http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&DEPA=0&Order=BESTMATCH&Description=dd+wrt) that might work. - old headphones/headsets/stereo audio cables and phone cords for cutting up and making into modem to radio connectors ### Radio - radio shack/hardware store high bandwidth unlicensed spectrum - Hacked FRS/GMRS radios - [Text messages over walkie-talkies.](http://takethingsapart.blogspot.com/2010/07/note-before-constructing-device-such-as.html) - [Forum post with some ideas.](http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1270645507) - Pros: - cheap - longish range (35mi allegedly) - Cons: - Need an automated PTT switch or two radios per node - Develop improvised antennae to improve signal quality, distance covered. - anything + aluminium foil = bouncy bouncy for radio waves The FCC has designated a number of channels in the 27 MHz band that can be used for signaling and radio control. They are unnumbered and in-between CB channels 1-13 ([source](http://forum.servomagazine.com/viewtopic.php?f=1&t=2736)) ### Optical - Modified Ronja-like - with lasers - with balloon targets - with lasers and balloon targets - with lasers and self-adhesive mirrored decals. - All Electronics Magazine had a couple of articles on building lasercomm devices on the cheap. Somebody remind the Doctor to go through his magazine collection. - [How to make a simple laser communicator.](http://www.make-digital.com/make/vol16/?pg=69#pg69) (I do have this issue. Have bought parts to build a pair of transceivers. --The Doctor) - [Handbook of Optical Through-the-Air Communications](http://www.imagineeringezine.com/files/air-bk2.html) is a good read on the basics of an LED-based hardware setup, though he's aiming at voice comms. (Elliot) ### Inspiration - [Ronja](Ronja "wikilink") ### Homework - read up on [Ronja](http://ronja.twibright.com/) - read up on FMRS/GMRS - read up on and talk to the HacDC Spaceblimp team about soundcard modems: like [this](http://www.baycom.org/~tom/ham/soundmodem/) (also available via apt [like so](Notes_on_Soundmodem "wikilink")) - [Howto](http://www.linux-ax25.org/wiki/Soundmodem)(go here last it's a bit short on soundmodem specific info) - [Notes on Soundmodem](Notes_on_Soundmodem "wikilink") - [Soundmodem in the field.](http://www.qbjnet.com/packet.html#soundmodem) - Read up on [AX.25](AX.25 "wikilink"). ### Goals (proposed) - Optimize for hackability. Could your average geek build a few of these using junk around zir house and deploy them in an emergency situation? - not a chance - Determine the optimum speed in bits per second for a mesh-to-mesh link. - very crazy slow (we didn't bother measuring it was so slow) - Measure the bandwidth of a point-to-point long haul connection at a particular distance. - again to slow to bother - Determine the maximum practical distance for a long haul connection between two meshes in an urban environment. - didn't get that far - Mathematically describe the way to maximize throughput with a minimum number of nodes. - didn't get that far - Run an ssh session over whatever link is established. - done - Interact with a web page over whatever link is established. - connection was too unstable to get this far - Develop methods to minimize latency. - tweak the source and transmitter volume A LOT until the it's perfect - Determine the efficiency of the mesh routing protocol we settle on. - didn't get this far - How many active nodes per mesh can be reasonably supported before connectivity breaks down? - to be determined ### Apps running on Windbringer (laptop/node) to prove functionality - [status.net v0.9.6](http://status.net/open-source) - [Mediawiki](http://www.mediawiki.org/wiki/MediaWiki) ### Lessons Learned - "how hard can it be" ... oops :( - very. soundmodem is finicky and creates unstable connections 20% packet loss at best 80-90% avg. - Don't forget network latency of 35,500ms over a distance of eight feet. - "What could possibly go wrong?" ... oops :( - everything - [There are no experimental failures. There is only more data.](http://drwho.virtadpt.net/archive/2011/04/14/project-byzantium-development-sprint-2) Let's see how much of [Project FabFi](http://fabfi.fablab.af/) we can make use of!