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”: https://www.cq160.com/rules.htm 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.
Hardware.
The 160m receiver is Afedri-Net SDR, 80m receiver is RTL-SDR stick with the homemade ON1BES SBL1 upconverter https://www.on1bes.be/sdr_up_conv_v3.0_ade1_125_en.html 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.
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 https://fairs.org/
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.
Start with downloading the SD card image https://www.openwebrx.de/images/2021-08-03-OpenWebRX-full.zip from OpenWebRX site https://www.openwebrx.de/download/rpi.php
Download and install BalenaEtcher https://www.balena.io/etcher/ and flash OS image to SD card (16G and more)
Follow the PA3FWM WEBSDR instructions https://semislave57.rssing.com/chan-30397001/latest.php
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 libcrypto.so.1.0.0 for the HTML5 audio stream.
Download and install the following libraries from the debian pool http://ftp.debian.org/debian/pool/main/o/openssl/
http://ftp.debian.org/debian/pool/main/o/openssl/libcrypto1.0.0-udeb_1.0.1t-1+deb8u8_armhf.udeb
http://ftp.debian.org/debian/pool/main/o/openssl/libssl-dev_1.0.1t-1+deb8u8_armhf.deb
http://ftp.debian.org/debian/pool/main/o/openssl/libssl1.0.0_1.0.1t-1+deb8u8_armhf.deb
http://ftp.debian.org/debian/pool/main/o/openssl/openssl_1.0.1t-1+deb8u8_armhf.deb
When all necessary libraries are installed and websdr.cfg file is formed, the websdr-rpi starts with no errors.
To setup Afedri-Net receiver, two software packages:
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 https://hamprojects.files.wordpress.com/2020/09/rpi-part-10-v1.0.pdf
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:
#!/bin/bash
cd /home/websdr/dist11
sleep 1
sdr_commander -sn256000 -g20 -q0 -f1890000
sleep 5
rtl_tcp -d 0 -s 1024000 -f 8350000 -a 127.0.0.1 -g 30.0 -p 1234 -b 3 & sleep 10
rtl_tcp -d 0 -s 1024000 -f 5050000 -a 127.0.0.1 -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 127.0.0.1 -g 30.0 -p 1234 -b 3 & sleep 10
rtl_tcp -d 0 -s 1024000 -f 5050000 -a 127.0.0.1 -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.
Setting-up the system.
6.Connect 12V power cable to the WEBSDR receiver box. Connect power interconnection cable to the filter box.
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
