Funcube Dongle smoke testing

Funcube DongleAs I tweeted last Friday, I managed to get a Funcube Dongle this time! The dongles were packaged over the weekend and shipped Monday this week. I could pick up mine at the local post office earlier today. Initial smoke testing using Linux and GNU Radio has been very encouraging for further experiments.

I started with plugging in the device and checking dmesg:

[80137.200016] usb 4-2: new full speed USB device using uhci_hcd and address 2
[80137.400105] generic-usb 0003:04D8:FB56.0003: hiddev96,hidraw2: USB HID v1.11 Device [Hanlincrest Ltd.
FunCube Dongle V0.0  ] on usb-0000:00:1a.1-2/input2
[80137.491011] 2:1:1: endpoint lacks sample rate attribute bit, cannot set.
[80137.492295] usbcore: registered new interface driver snd-usb-audio
[80137.564030] 2:1:1: endpoint lacks sample rate attribute bit, cannot set.
[80137.568028] 2:1:1: endpoint lacks sample rate attribute bit, cannot set.
[80206.837145] 2:1:1: endpoint lacks sample rate attribute bit, cannot set.

It shows up as an audio input device and one can start recording 96kHz stereo audio. There is not much point in doing that though except that it sounds funny.

Funcube Dongle input device

To make the device usable by regular users I created a udev file in /etc/udev/rules.d/20-fcd.rules containing:

SUBSYTEMS=="usb" ATTRS{idVendor}=="04d8" ATTRS{idProduct}=="fb56" MODE:="0666" SYMLINK+="FCD"

Then reload the udev rules with “udevadm control –reload-rules”

I built the qthid controller application and I could use it to change the frequency; however, clicking the “Switch to bootloader” didn’t have any effect. I had to use the windows application to upgrade the firmware from 18b to 18f. The PDF guide on the download page provides good info about how to upgrade the firmware. Once the firmware upgrade was done, I moved the Funcube Dongle back to the linux box and could use it in a simple GNU Radio flow graph.

FCD test with GNU Radio - FFT

I am not entirely sure about the mapping of LEFT/RIGHT I/Q in the GRC flow graph, in particular when they are combined into a complex format. Will have to investigate later.

This video shows me fooling around in the broadcast FM band. The bandwidth of the Funcube Dongle is too small (96 kHz) to receive a whole wide FM transmission so I am looking at the edges to see that something is happening. I was using a paper clip antenna as shown in the beginning of the video.

Watch video on YouTube.

It seems to work well but there is some work to do on the controller side before it can be really useful on Linux. The existing Qt controller can only change the frequency, while the fully featured windows application can tune all sorts of gains and filters. Fortunately, the source code for the windows application is available and we can use that to create a linux version.

My Funcube Dongle photos are available in this Flickr set. I will update as I take more photos.

SMA connector on the Funcube Dongle