FUNcube SDR Dongle Overview and First Impressions
I finally got to spend about six hours playing with the FUNcube SDR dongle and feel like I only scratched the tip of the iceberg. The FUCcube dongle is an all mode VHF / UHF SDR radio that covers 64 MHz to 1700 MHz (with a small gap between 1100 MHz and 1270 MHz). With the proper firmware installed it will even go down to 51.5 MHz and beyond 2000 MHZ. The FUNcube Dongle is completely housed in a USB dongle that is a bit smaller than an usb TV tuner dongle. The FUNcube Dongle also has a SMA antenna connector on the other end. The quadrature sampling rate is at 96 kHz with 80 kHz useable. Sensitivity is rated at 0.15uV for 12dB SINAD NBFM at 145MHz and 435MHz. The center frequency of the FUNcube dongle can be set by software.
At this time I would have to say that the FUNcube dongle (FCD) is more of an experimenters SDR radio than a finished product. Don’t expect to get a packaged system that includes custom software or a fancy manual. The firmware and other programs are undergoing fairly regular updates and tweaks. You pretty much just get the FDC and the rest is up to you. So there is a small learning curve to get started. However, the FDR is a tremendous value when compared to other VHF / UHF SDR radios or other all mode VHF / UHF receivers in general. With that being said, let me go over my impressions of the FUNcube sdr dongle.
At this time purchasing the FCD dongle can be a bit tricky. Since the FCD has come available, they literally fly of the shelves in seconds (I don’t think they ever make it to a shelf). FCD sales are usually announced on the FUNCube website once a week. The sale starts at a certain time (usually 2100 UTC) and normally consists of 100 units. Due to the popularity of the FDC, they typically sell out in a matter of minutes. This should get better over time as the FDC sales reach a saturation point. The FDC is sold in the UK, but the shipping is typically very fast. I received mine in about two days via Fedex and it was well packed. The current price of the FDC shipped to the US is approximately $180.
The build quality is actually pretty good. The dongle housing is made of sturdy plastic.
I would say that the weak point as with most /usb devices would be the USB connector itself. Since the antenna connector is a SMA connector, you may have to use adapters to connect to your existing antennas. These adapters and the accompanying cable could possible put a lot of strain on the USB connector plug. The work around would be to use a short USB extension cable so all this extra weight won’t be hanging of your computers USB port. However, if you want to use it portable with your computer a small flexible whip antenna would probably be fine.
The hardware installation couldn’t be easier. Just plug the FCD into an available USB port on your computer. For most newer PC operating systems, no additional drivers are needed. The FCD is seen as a class complaint audio device in Windows and Mac OSX. If you are running an older version of Windows XP, you may have to install some additional drivers. Installation of the FCD hardware couldn’t be simpler. Plug in the FCD to a USB port, connect your antenna, install some SDR software, and your off.
Here is where things get a little more interesting. The first thing you should do is join the Yahoo group funcube.This is where you will find most of the software that you will need to use the FCD. Check out the Files section of the group. The first file you will want to get is the latest FCHID program.
The FCHID program lets you set the center frequency of the FCD. While you are there, grab the FCHIDBL file ( I will explain later). Once you set the center frequency with FCHID , you can start any SDR decoding program that accepts IQ signals. Simply set the input selection in the program to the FCD device. You should now start seeing and decoding signals from the FCD. The FCHID program also lets you tweak the filter and gain settings of the various stages of the FCD. These may come in handy for experimenting with various configurations of the FCD with LNAs. Don’t worry about messing things up, in the FCHID program there is a return to defaults button. The FCHIDBL is the bootloader program used to update the firmware in the FDC. You will need to read the howto, because it’s not particularly straightforward in regards to updating the firmware. Once you do it once, you will find it to be a very easy process. If you are interested in getting access to the lates firmware and software betas, you will need to join the FDC Development group.
Probably the best SDR program right now for general use of the FCD is HDSDR.
The program is available for download in the SDR directory of the funcube file section. One of the main reason for this is that at this time, it is the only SDR program that will allow you to tune the FDC without the use of the FCHID program. However, it won’t do it without a simple modification. You will need to download ExtIO_FCD.dll from the files section of the funcube group. Simply drag this file to the same file directory you have HDSDR installed in. Restart HDSDR and the program should now tune the FCD. Another interesting program available for download for the FCD is SATCONTROL_FCD. This program will tune the FDC to track the doppler shift of a satellite downlink frequency. SATCONTROL will take a TLE file to allow you to update the software with the most current satellite tracking information. To get SATCONTROL to work with the FCD tuning you will have to place the ExtIO_FCD file in the SATCONTROL directory.
SATCONTROL is not a a full blown satellite tracking program, in that it doesn’t show maps and data about the satellites. SATCONTROL simply automatically tunes the FCD to receive the satellite downlink signal. You can probably use SATCONTROL along side your favorite satellite tracking program.
As you can see the framework is there for a really good SDR program to come along and integrate all the SDR features. With the ExtIO_FCD.dll being available this should allow 3rd party software developers like Ham Radio Deluxe to easily integrate the FCD for scanning and satellite tracking. With proper software the FCD could also be used as a computerized trunk tracking radio. You can also use the FCD with various amateur radio decoding programs for packet and other digital modes. You can use the Virtual Audio Cable (VAC) to route the audio output from the FCD to the decoding program. The possibilities for an inexpensive VHF / UHF receiving system are endless with the appropriate software.
I took a look at the sensitivity of the FCD using some realtime signals. One of the things you should be aware of with the FCD is that it has a very wide front end without a huge amount of filtering available. For this reason if you live very near the source of a strong FM signal you may run into desensing issues with the FCD. This will make the FCD seem deaf to other signals you are trying to receive. Some users have mitigated the problem by using a bandpass filter for the offending band. Fortunately, I did not have this problem. The other thing to be aware of is that very strong signals can possibly overload the front end of the FCD. It is best to use an antenna specifically for the band you are trying to receive. You can also lower the sensitivity of the FCD with the FCHID program. For testing purposes I used a 2 Meter whip, 2 Meter vertical, and a wide band VHF / UHF discone with unity gain.
Using the 2 Meter whip, I found that in the two meter band the FCD compared favorably with my Uniden BC 246T scanner. However when compared to my Wouxun KG-UV3D HT, the Wouxun was noticeably more sensitive. So using the whip was sort of a mixed bag. A 2 Meter dedicated radio will probably always do a bit better than a wideband receiver.
With the 2 Meter attic mounted vertical things were a bit different. I am using a Flex 1500 paired with an Elecraft XV144 transverter for weak signal 2 Meter contacts. This has been an excellent combination for weak signal FM since the XV144 has very good sensitivity in this band. I tuned to the APRS frequency of 144.390. I usually receive a very weak APRS beacon from the west. The XV144 could pull it out of the mud and to my surprise, the FCD could also. The signal from the XV144 was only slightly stronger, but not by much. I felt the FCD did a very respectable job in this test.
Next I tried the FDC with the wideband discone. For this test I compared the FCD to my Icom PCR1000, which is a wideband all mode HF,VHF, and UHF radio. The PCR1000 is more of a conventional radio with better filters and is simply tuned by a computer program. The FCD pretty much held it’s own against the PCR1000 in several areas. The FCD actually performed a little better in the 800 MHz range than the PCR1000. The most noticeable difference is that the PCR1000 was a bit quieter than the FCD because of its better filters. However you have to remember, that in its day the PCR1000 costed at least twice as much as the FCD. It also didn’t overload as easily. One of the places that the FCD doesn’t do very well is in decoding wideband FM. You can sorta do it, but not without some distortion. The only SDR program that even came close to decoding WFM was Spectravue. I understand with some tweaks you can improve WFM reception, but I wasn’t too interested in tinkering with this.
In my opinion, the FUNcube dongle offers a lot of value for the money. It’s an excellent way for beginners to dip their toes into the world of SDR radio. For more experienced users it also offers a way to inexpensively add VHF / UHF SDR to their current SDR setups. Does it compete with units that are two to three times more expensive? Probably not, but it’s not bad either. With better software support and if the price stays near the same, it could become a killer deal for an inexpensive VHF / UHF SDR radio platform. There are also plans for an “educational” version of the FUNcube, that will be slightly less expensive and have less frequency coverage than the FUNcube Dongle Pro discussed here. I would say that the SDRfuncube is an SDR radio to watch. With all the interest the FUNcube dongle has generated, there should be some interesting software and applications for it in the future.
Here is a video of the Funcube dongle and HDSDR receiving an AM ASOS signal from the airport using a wideband discone antenna.
This video shows the FCD decoding an FM broadcast from the NWS using the same antenna.