Category: JS8CALL

Many years ago I purchased a Funcube Dongle Pro+ (FCD) SDR. Since it’s arrival it has just been stored in my “Get round too it” drawer.

It’s been many years but, today is the day it comes out into the light and finally gets powered up.

I’m hoping to be able to use the FCD as the receiver in my QO-100 satellite ground station setup.

The output from the 10Ghz dish mounted LNB is around 739Mhz, well within the FCD receiver range of 150khz to 2Ghz. This will save me from having to transvert from 739Mhz to 430Mhz (70cm band) on the receive path.

This will also give me full duplex operation as I will use my Icom IC-705 on the 2m band (144-146Mhz) to drive the 2.4Ghz transverter for the satellite uplink whilst listening to my own signal via the 10Ghz downlink fed into the FCD.

Before I can even start to build the QO-100 satellite ground station I need to get to grips with the FCD, get the software installed, configured, resolve audio routing via virtual audio cables and get it decoding FT8/JS8/WSPR etc.

Talking to G0DUB in the General Amateur Radio Chat room on Matrix he recommended trying the GQRX software to drive the FCD. GQRX is open source which fits perfectly as I want to control the FCD from my Kubuntu PC.

Checking the Ubuntu repo’s I found that GQRX v2.12 is available for installation.

sudo apt install gqrx-sdr

Once installed I fired up GQRX and set about configuring it. Initially it appeared to have automatically detected and configured the FCD however, when I started the FCD the software ran for 5 seconds and then just hung.

Diving into the configuration settings I found that the FCD actually appears twice in the list of available devices and all I had to do was select the other one in the list and start the software again and all was well.

I connected my 20m Band EFHW Vertical antenna and trawled up and down the band. The receiver performed well even with fairly strong signals so, I spent some time listening to a few of the stations coming in from the USA.

Next I wanted to sort out the configuration for digital modes. I already have a couple of virtual audio cables in the form of loopback audio devices configured on my Kubuntu PC as this is how I connect the audio between WFView for the IC-705 and WSJT-X/JS8CALL.

Sadly, GQRX doesn’t recognise the loopback audio devices that already exist and so I had to do a little further research to get to the bottom of the issue.

Digging deeper I discovered that GQRX requires loopback audio devices created using Pulse Audio and not the kind I had already created at the O/S level. A quick read of the pactl man page and some further searching online I found all the info I needed to create the correct kind of loopback audio devices.

Two commands are required to create the pulse audio server audio loopback devices:

pactl load-module module-null-sink sink_name=gq2jt sink_properties=device.description="gq2jt"

pactl load-module module-loopback latency_msec=1

Once I’d created the loopback audio devices I was able to select the gq2jt devices in both GQRX and WSJT-X/JS8CALL so that the audio was routed correctly.

The overall solution works well and doesn’t put much load on the CPU of my Kubuntu PC, leaving plenty of horse power for me to do other things at the same time.

So I now have the Funcube Dongle Pro+ working perfectly on my Kubuntu PC, all I need now is a 1.2m dish, a 10Ghz LNB and some high quality coax cable.

UPDATE: I decided to leave the FCD connected to the 20m Band EFHW Vertical overnight and monitor FT8 on the 40m band. The EFHW antenna isn’t anywhere near resonant on the 40m band and so I thought it would be interesting to see how well the FCD performed on a completely non-resonant antenna.

To my surprise it did exceptionally well, stations from all over the world were heard with ease, the FCD really is an excellent little SDR receiver.

If you’re looking for a relatively cheap but, effective receiver for FT8/WSPR monitoring then I can highly recommend the FCD. If paired with a RaspberryPi then it would be a really cheap to purchase/operate solution for any HAM operator or short wave listener (SWL).

More soon …