Quadcopter Part 3.2: Fixing the poor wireless performance

I stumbled upon this site from Adafruit.  It talks about a number of problems with Wireless on the Beaglebone. One of that is poor driver support for RealTek based devices, which I’ve also ran into, and it informed me that the HDMI circuit causes a lot of signal interference, and that degrades the performance of small wireless USB dongles in particular because of their close proximity to that circuit.

So their solutions are worth a try as well.
To fix the HDMI interference they propose to:

  • Disable the HMDI circuit in the bootloader configuration
  • Move the USB dongle away from the board, either with a USB extension cord, or with a small USB hub.

In my quadcopter case, I’d rather not add more hardware, and I don’t need the HDMI interface, so I’ll just try to turn it off, following the steps on the Adafruit guide. To be honest, after doing the steps and rebooted the board I don’t see such a major improvement with the HDMI off.

To fix the driver issue, they don’t upgrade the kernel to the testing image, but instead upgrade to the latest stable and then install a service which will reset the wireless dongle during boot, in order to stabilize it. But in my case, when using the testing (3.16) kernel, it does more harm than good: the wireless connection doesn’t appear to come back up after reboot.

The wireless saga continues…

UPDATE: to give you some idea on the level of poor performance. I ran iperf from the beaglebone to my laptop over the wireless network here at home, and it report over a 1 minute interval an average speed of about 450Kbits/sec. If I move the dongle further away from the board, by using a USB hub, I get 730Kbit/sec, which is only marginally better.

UPDATE 2: even the wired network is very limited in bandwidth, more tests are needed to find out what is going in here. In the mean time I ordered a new type of USB dongle, one from the list on the beaglebone wiki. Hopefully that works.

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