Those interested in Low band Dxing are aware of the importance of the ability to copy weak DX signals, especially on 160 meters. Unfortunately, the noise situation in urban areas is worsening daily. So, the obvious solution is to install the WEB receiver in some quiet rural place away from the noise sources.

The first attempt to make this was initiated by VO1HP’s idea to use the remote Afedri SDR-NET receiver.

So, the Afedri receiver was purchased and installed on a temporary basis at the Skiing Carpathian mountain site. This was “one band (160m)/one user” project using the fiber optics cable ¼-in Standart Steel Messenger as the long wire antenna which proved to be very effective with the 20Mbit Internet access speed and low noise from fiber optics to Ethernet converters.

The next step was to install the public WEBSDR not far from Lvov for an easy maintenance access and possibility for local club members to use it.

PA3FWM WEBSDR software which has the shortest signal processing delay time (perfect for the contest use) has been chosen for this project. Obviously, the WEBSDR site would had to be situated in accordance with the “100 km contest rule”: that says:

For Single Operator Assisted Only: “The use of one and only one remote receiver located within 100 kilometers of the main transmitter site is permitted, in addition to the receiver at the transmitter site. WebSDRs are OK, but must be located within the 100-KM limit.” 

The WEBSDR v.11 software and RTL-SDR stick was tested on 50MHz this season.

It was decided to install the 160, 80 and 6m WEBSDR at the country site 30 km from Lvov in KN19XM.


The 160m receiver is Afedri-Net SDR, 80m receiver is RTL-SDR stick with the homemade ON1BES SBL1 upconverter with corresponding two band splitter, highpass and bandpass filters and W7IUV 2N5109 preamplifier.

On 50MHz the RTL-SDR stick with SPF5122Z preamplifier is used.

Antennae are the fullsize 160m delta loop 4 m up and 50 MHz dipole.



Software installation

PA3FWM WEBSDR software v.11 worked perfectly on Ubuntu 16.04 desktop but we decided to switch to Raspberry PI4 having in mind low energy consumption with the possible solar power installation at the quiet remote sites in the future.      The Raspberry PI with all accessories, power supply, SD card and SDD 120Gb HDD were donated by FAIRS Inc., Floyd VA

Several attempts to install PA3FWM software using different Raspberry OS installation packages were made and the only OpenWebRX Debian package was OK for this purpose.

Raspberry PI4 computer unit.

Software installation

Start with downloading the SD card image from OpenWebRX site

Download and install BalenaEtcher and flash OS image to SD card (16G and more)

Follow the PA3FWM WEBSDR instructions

The same file is in unzipped websdr-dist11.tgz file (../dist11/doc/install.txt).

Install necessary libraries mentioned in the installation guide:             (libfftw3-3 libpng12-0 etc)                                                       The software needs for the HTML5 audio stream.

Download and install the following libraries from the debian pool

When all necessary libraries are installed and websdr.cfg file is formed, the websdr-rpi starts with no errors.

Setting up receivers

To setup Afedri-Net receiver, two software packages: and                  

and corresponding libraries (libudev1,libudev1-dev,libasound-dev, etc) have to be installed.

Copy both sdr_commander and sdr_split to /home/websdr/dist11

Make the FIFO file: create the directories /home/websdr/band160/fifo/ and run the command: mkfifo /home/websdr/band160/fifo/afedri-ch-1

Set the device in /cfg/websdr.cfg                                             

device /home/websdr/band160/fifo/afedri-ch-1                                    

device $hw 1:0:0

To avoid any possible conflicts between ALSA devices I suggest disabling the PI4 onboard sound card:

cd /etc/modprobe.d

create the file

sudo vi alsa-blacklist.conf

and enter the following line: 

blacklist snd_bcm2835 

Save the file and reboot the machine

To set up RTL-Sdr please follow the installation guide from F4GOH

When using the RTL-SDR with upconverter one has to know that there’s a bug in websdr v.11 than requires to restart the rtl_tcp driver after starting the WebSDR software (websdr-rpi).

Set the bands and fill the rest of websdr.cfg fields in accordance with /home/websdr/dist11/doc/config.txt ended with swapiq command and start the software.

In our case the startup file looks like this:                                    

cd /home/websdr/dist11                                                            
sleep 1
sdr_commander -sn256000 -g20 -q0 -f1890000
sleep 5
rtl_tcp -d 0 -s 1024000 -f 8350000 -a -g 30.0 -p 1234 -b 3 & sleep 10
rtl_tcp -d 0 -s 1024000 -f 5050000 -a -g 30.0 -p 1235 -b 3 & sleep 5     
cd /home/websdr/dist11   
./websdr-rpi &  sleep 6
killall -KILL rtl_tcp                 
sleep 6 
rtl_tcp -d 0 -s 1024000 -f 8350000 -a -g 30.0 -p 1234 -b 3 &   sleep 10   
rtl_tcp -d 0 -s 1024000 -f 5050000 -a -g 30.0 -p 1235 -b 3 &   sleep 5    
exit 0

If everything is configured correctly WEBSDR program starts and can be reached by any browser at port 8901

Hardware items list.

  1. RPI4 computer box (RaspberryPI4 board, SSD HDD 120GB, M.2 (NGFF) to mini SATA SSD adapter card).
  2. Video cable with DVI converter.
  3. RaspberryPI4 3.5A power supply.
  4. WEBSDR 160/80m receivers box
  5. FILTER unit and 2N5109 LNA boxes.
  6. Interconnection 80 and 160m band coax cables.
  7. WEBSDR < – > FILTER unit power cable.
  8. USB cables for receivers (total 3)
  9. 12-15V 1A linear PS for for LNA+relay and upconverter.
  10. 9V 1A linear PS for Afedri SDR and shielded power cable.
  11. 12V shielded power cable for LNA+relay and upconverter.
  12. 5V shielded power cable for 50 MHz SPF5122Z LNA (optional)
  13. Separate RTL-SDR stick for 50 MHz and set of antenna coaxes

Setting-up the system.

  1. Open the computer cabinet and connect video and power cables to RaspberryPI4 board.
  2. Connect RJ45 network cable.
  3. Connect three USB receiver cables to the RaspberryPI4 board through the front panel.
  4. Close the cabinet.
  5. Connect USB cables to the corresponding receiver female connectors on WEBSDR receiver box. Black USB cable is connected directly to the RTL-SDR 50 MHz receiver.

6.Connect 12V power cable to the WEBSDR receiver box. Connect power interconnection cable to the filter box.

  1. Connect 160 and 80m coax cables between WEBSDR and FILTER boxes.
  2. Connect antenna 160/80m antenna to the FILTER unit antenna connector.9. Connect 50 MHz antenna coax the input SPF5122Z LNA connector.

Important notes.

The Raspberry PI4 3.5A power supply can’t handle the additional 500 mA load of Afedri SDR via USB port resulting in computer freezing due to PS overload.

The 9V 1A linear PS has to be used for Afedri SDR. Avoid trying to use the 12V PS as the internal Aferdi SDR 7805 chip is becoming too hot for 24/7 usage.


Final adjustments.

Set the fixed IP, subnet mask, gateway and DNS in /etc/dhcpd.conf