802.11ac SOWN Zepler

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This is a project to build a new SOWN Zepler node that provides wireless access using the 802.11ac standard.

SOWN-Zepler base unit 1.jpg SOWN-Zepler base unit 2.jpg

Task List

  • Determine how mount antennas for SDRs.
  • Get SDRs working with current firmware.
  • Cover whole front of internal mounting plate with Velcro.
    • Apply reverse velcro to SDRs and POE splitter
  • Mount additional mounting shelf to IP56 metal box.
    • We already have some M4 nuts/bolts. These are a bit smaller than ideal but it is fiddly to get nit onto bolt. Might use blue tack to hold nut in place and then try in bolt.
  • Laser cut modified design of connector plate, as original had the following issues.
    • Lightning arresters cannot be placed adjacently.
    • The original design had N-Type connectors holes that were about 1mm or so too narrow.
    • As plate is not metal we are not grounding connector chassis
    • Tyler has done a redesign and has the spare acrylic from which the plate can be cut. Once we have a plate we are happy with we should cut plin round holes in the metal plate and use both plates (acrylic and metal) one on top of the other.
  • Mount connectors to connector plate.
  • Mount connectors plate to box.
  • Fit some rubber washers to mounting bolts between box and external mounting plate for better waterproofing.
  • Finish getting firmware working so both nodes and the SDRs work with the APU board running Debian.
  • Do a fully assembled test of:
    • 802.11n card
    • 802.11ac card
    • SDRs

Component List

This lists all the items we already have for building the new 802.11ac Zepler node.

Shopping List


Bought (awaiting delivery)

Nothing currently awaiting delivery


  • May need 2 x filters for the USB SDRs


To make it easier to install and configure the SDRs, a 64-bit version of Debian 8 (Jessie) has been installed on the MSATA SSD.

Installing the Operating System

Netbooting Debian

Netbooting is the easiest method to install debian on the APU board. This is because it allows for easy modification of the installation files to force the board to install over a serial cable rather than using a video output. The APU board we were using is a difficult one as it also has a graphics processor with no display connector. Hence, the installer tries to use this and we get no idea what's going on.

To netboot the board, I used instructions from this link. [1]

During the installation, select the following options at the package selection stage:

  • DISABLE Debian Desktop Environment (extra overhead for a server device)
  • ENABLE SSH Server
  • ENABLE Standard System Utilities . Seemed like we could need them at some point.

Remember to install grub.

Post-installation setup

Check everything's up to date

su root
<password entered during setup>
apt-get update

If you used the guide I suggested above, you've now ended up with Debian 7 (Wheezy) installed. Let's update it to Debian 8 (Jessie) Now, edit /etc/apt/sources.list, replacing all instances of 'wheezy' with 'jessie' Then,

apt-get update
apt-get upgrade
apt-get dist-upgrade

Now, install a newer kernel. In this case, we upgraded to 4.9 from 3.2. I used this [2]

Edit sources.list to include backports

deb http://ftp.debian.org/debian jessie-backports main
apt-get update
apt-cache search linux-image
apt-get install -t jessie-backports linux-image linux-image-amd64

And now we're running a really recent kernel.

Now, add non-free to each of the items in /etc/apt/sources.list (I did this for the first two (jessie) and also the (jessie backports) entry)

Now to install the drivers for the Broadcom NIC

apt-get install broadcom-sta-dkms wireless-tools

It's likely time for a reboot now....

sudo reboot

(Hopefully it'll come back up)

ssh user@<sown-zepler-ip>

It lives! Let's just check it's running the new kernel we installed...

uname -r

Ok so the kernel upgrade broke the broadcom firmware. Install these things first and then reinstall the firmware.

Basically, install as many headers as you can, (sudo apt-cache search linux-headers) and it works


sudo apt install broadcom-sta-dkms

Now to install ath10k with associated firmware.


Configuring as a SOWN node

To be completed

The steps required to configure the system to work as a SOWN node should be saved as Puppet scripts, so that these can be reused if we want to build a second node or need to rebuilt this node after a failure.

The general day-to-day configuration should still be manageable through the SOWN admin system. Therefore, the configuration needs to include a script that can pull down configuration files to update aspects of the system, such as wireless channels to use.