Tuesday, November 19, 2013

Don't Panic, it's a Serval Mesh Extender

I have been working on the firmware for the Mesh Extenders the last couple of weeks.

This has involved combining a few features to make a 0.01 release that can go out on the perk Mesh Extenders, as well as some WR703N-based mesh extenders we are preparing for a monastery (more on that in a later post).

I wanted the firmware to support updating of the servald binary and config file, as well as preventing login as root in normal operation, and operating a captive portal so that people connecting to a mesh extender get some idea of what is going on. It also needs to support the different hardware types we are using.

This is all finally coming together as the following image shows.   The captive portal automatically pops up on my Mac if I associate with a mesh extender by Wi-Fi.

I'll talk more about the firmware structure later, and document it on the wiki.  Anyone wanting to take an early look can checkout the source code and look in the somewhat erroneously named mr3020 directory.

But for now, I am happy that we have the main functions of the mesh extender firmware functioning.

Tuesday, November 12, 2013

Open-Source Collapsable Communications Tower

[Update: the design files to make your own tower are now available via this post.]

I have been helping some mechanical engineering students from the side-lines with a project to make an open-source rapidly-erectable communications tower, with internal space for comms gear and batteries.

I hadn't caught up with them for a few months, but today was student expo for the department, and so I went down to see what they had created.

It was very pleasing to see a nice that they had indeed managed to make a 6m high tower that can be assembled in less than 10 minutes, and consists entirely of common hardware and a few 3D printable parts, as you can see below:

And again with one of the students who designed it for scale:

The design uses three guy ropes for stabilisation, and was designed to accept an 85m/s static wind load.  The practical limit would be less than that under realistic dynamic wind conditions.

Following my suggestion, the entire tower when broken down is small (<140cm total linear dimensions, approximately 1m in longest direction) and light enough (19kg) that it can be included in checked luggage on a normal commercial flight.

By using only common plumbing components and a few 3D printed components, it could in principle be manufactured (or repaired) in relatively infrastructure deprived settings, provided you had a 3D printer, of course.

Think you'll have trouble finding 3D printer filament?  Then you might want to make use of one of the other student's projects, turning plastic milk bottles into 3D printer filament.  That project has a bit more work to do, but the general concept is there and working.  There are also some other projects around the world working on the same kind of resource scavenging approach.