New front end for use of the Red Pitaya in SDR applications

The Red Pitaya SDR board is based on the Xilinx Zync SOC and has 14 bit external A/D converters. However, for SDR usage on the HF bands from 0.1-30 MHz (and for that matter up to 50 MHz) the Red Pitaya is a bit “deaf” in the stock configuration. I have made a broadband amplifier that has a fairly high gain and very good IIP3 properties. Below I have posed some pictures of the prototype amplifier.

20160424_153046-1This is the prototype amplifier. I inserted a ferrite ring on the input lead to roll off the VHF / UHF sensitivity to reduce problems with nearby broadcasters etc. There is a also a PI network attenuator on the ouput and I have inserted a couple of beads in that as well to roll of the outpu response when frequency increases. The other components in the lower part is a input pi attenuator I used when I did some VNA frequency response measurements. This as well as the RCA plus is not used (RCA plugs are surprisingly good for low level RF signal routing in the HF bands and nice to use in the lab).  I used a more professional attenuator with a large attenuation range and flat response to determine the proper attenuation level after the preamp into the Red Pitaya. Reducing gain after the first amplifier has very little effect on the noise figure. Reducing it before the first amplifier directly adds to the noise figure. I added some protection diodes over the input to reduce the risk of strong RF signals or static voltage build up damaging the input. Below I am measuring the response of the attenuator with the DG8SAQ VNA. It was flat from 0-1,3 GHz.






Red Pitaya SDR TX / RX

The Red Pitaya hardware is the first low cost RX / TX capable SDR hw to come onto the market that is open source and can match the Ettus Research USRP periperhal. It has a combined CPU and FPGA signal chain with  two channels 14 bit 125 MSPS A/D and D/A. It also has a Dual core ARM Cortex A9+ FPGA (Xilinx Zynq 7010 system on chip). Only a few years ago this caliber of hardware had to be custom designed and was typically used in radar antijamming systems, radar signature classification systems, ultrasound, sonar and in high end vibration analysis tools (as examples). The ARM CPU on board can run Linux and it has GNU-Radio support. For fast data transfer there is a GBE (Gibabit Ethernet) interface to other host systems. With a a RTOS on the ARM core or a zero copy IP stack under Linux it should be possible to approach fairly close to 1 Gbit/sek transfer rates to host systems (if needed).



HDSDR trackerball VFO project

I have been working on a trackball based controller for my HDSDR SDR project lately. This is a small R&D project that is run on my spare time where the goal is to determine if it is possible to use a trackball as a VFO for software defined radio (SDR) in contests. The project started out based on a demand for a more ergonomic way to operate a mult receiver in a contest environment that is less fatiguing during 48hours duration of a major contest like CQWW or CQWPX. The goal is that it should be possible to operate all radio functions you need from one hand only: VFO, speed of vfo, band, mode, filter width, volume, gain. I have modified a Marconi trackball and the controller is a Trinket Pro controller (Arduino)

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SdrDx and Funcube dongle. Receiving airband traffic


You should download and try out the new SdrDx console. It is compatible with your Funcube dongle. Finally a more advanced SDR console that has many of the features you need including several notch filters, memory functions, a very good and intuitive GUI. In fact I like the GUI style on this one! One minus is that it is not open source. The image above is a screen dump of Funcube receiver set to a QRG in the airband. The AM detector works very good. The SdrRx can be downloaded here at fyngyrz’s site

How to install SdrDx: Download zip. Unzip. Make a shortcut to the .exe file. If your Windows firewall gives you a warning, tell it to open up for that program. Make sure you have a new firmware installed on your Funcube (see other post for how to update).

HF converter for SDR Funcube dongle


Tony CT1FFU and Diogo CT2IRW has released a converter for the Fun Cube dongle. The design is a based on the old NE602 workhorse. One new approach is to use a wideband MMIC amp in the front end. The unit is powered via a USB connector. Looks like this may be a good add on if you want to do some basic HF monitoring with the Fun Cube. You can find more information here:

PowerSDR and Flex-Radio offerings becoming prime contest tools


FlexRadio systems is launching new products and new improved software all the time. I have been following the SDR scene for several years now and experimenting with the Softrock 40 and softrock RX-TX as well as some earlier VHF SDRs has been fun.

I must say that the offerings from flex-radio is now becoming more tempting than many offerings from traditional suppliers like Yaesu and Icom. My FT-2000 with the latest software is surely a great radio (the best I have had so far) but I think a FLEX-5000A with diversity RX and the newest PowerSDR software must soon be tried in a serious contest effort. The filters, diversity functions and FFT bandscope functions are simply great. One thing that lacks are the feel of real buttons and controls. But that has also been taken care of (read below)

Here you can see a video from Flex-Radio where they take the new tracking notch filters (TNF-RF)  for a spin:

In case you lack the feeling of a real radio, DH1TW is here demonstrating the use of a DJ controller for adjusting VFO and other radio functions:

Surely great stuff! Stay tuned!

How to upgrade the firmware of your Funcube dongle

I had some problems of getting my Funcube dongle (purchased dec 2011) to work with SDR-RADIO version 1.5 build 879 (beta). The reason was that the funcube dongle didn’t have the latest firmware.

The webpage is a bit unclear about how to do the upgrade, so here I have written up how to upgrade the software.


1 ) Goto

2 ) Select downloads

3 ) Download Windows fully functional front end

4 ) Download Boot loader with source code

5 ) Unzip those two archives in a suitable directory. (If you need a free zip tool, you can use the free WinRar software that you can download from Rarlabs homepage )

6 ) Make sure you close all other SDR programs that may acess the funcube dongle. This is important so that the funcube is not “occupied” by another program

7 ) Plug in your funcube dongle to one of your USB ports

8 ) Wait 10 secs and listen for the “bling” sound that windows sends to signal that a new USB unit was detected

9 ) Start the FCHID.exe file (the front end)

You should now see something like this –>


10 ) Click the read device. You should now NOT see any error message. In case the read went ok, you now have a connection to your funcube dongle

11 ) You now want to set the funcube dongle in the bootloader mode. This means that the funcube is ready to boot from new software.

Here comes the confusing part: you must start another piece of software to upload the new firmware to the funcube. You cannot do that from the FCHID.exe file. The software you use for uploading the firmware is FCHIDBL.exe

12) Start FCHIDBL.exe (from the CHIDBL___Win32_Debug subdirectory where you unzipped the Boot loader with source code ) file from point 4) above

13) Download the latest firmware from Firmware v18i – Save it to the same directory as you saved the other files.  NOTE per Jan 2012 this was the latest software but this may have changed when you read this !!! Check what is the latest file before you upgrade!

14) Now start the FCHIDBL.exe file. You should see something like this:


15) Click the Open file button

16) Select the *.bin file you saved earlier (the *.bin file contains the firmware)


17 ) At this point -> if you are on a laptop make sure your laptop battery is OK or that the laptop is plugged into a AC adapter, so that you don’t risk that your laptop shuts down while you flash the firmware to the Funcube dongle.

18 ) Click WRITE FIRMWARE button. Now click RESET TO APP to get out of boot loader mode (Thanks to Jeff Murri for this tip).

19 ) Close both programs you opened earlier

20 ) Wait 10 secs (just in case)

21 ) Plug out the funcube dongle  (Probably overkill, but hey…)

22 ) Wait 10 secs (to let windows have time to unload the driver. Not sure if this is really necessary. But hey …..)

23 ) Plug in the funcube dongle again

24 ) Congratulations, you have upgraded to the latest firmware !

Receiving wideband FM with the Funcube dongle


I have recently acquired a Funcube dongle software defined radio. The Funcube dongle is a small USB unit that contains a E4000 Silicon Tuner (radio on a chip), a TLV320AIC3104 Audio Codec and a Microchip 24FJ32GB002 16bit Microcontroller. This small USB device gives me coverage from 64 to 1700 Mhz with some small gaps according to the manufacturers data. You can download more information here:

As a windows SDR RX I am at the moment experimenting with the sdr-radio program that you can download here:

The picture above shows a FM broadcast transmitter in the Oslo area. You can also see the pilot carrier that is used to encode the stereo information if you look carefully