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This WebSDR setup covers a dual band receiver (80/40 meters bands) time-based switched. It uses a relay to switch between antennas who is managed by one GPiO pin on the Raspberry PI (using a driver transistor).
Very special thanks to Pieter PA3FWM, Mark G4FPH and Jarek SQ9NFI for the helpful hand on configuring the progfreq setting.
- Raspberry PI 3
- Raspbian 9 installed and working
- Internet access setup and working
- RTL-SDR USB Dongle
sudo apt-get update && sudo apt-get upgrade
sudo apt-get install g++ make libsigc++-1.2-dev libgsm1-dev libpopt-dev tcl8.5-dev libgcrypt-dev libspeex-dev libasound2-dev alsa-utils libqt4-dev
sudo apt-get install libsigc++ cmake groff rtl-sdr
- Copy the etc/rc.local file to your /etc/rc.local
sudo cp etc/rc.local /etc/rc.local
- Check and match GPIO ports for relay control to switch antennas and a button to soft reset the Raspberry pi.
- There is a Python script that handles Raspberry PI reboots from a hardware switch without killing power.
- Check the /etc/rc.local file and match the desired GPIO port for this task.
- Copy lib/systemd/system/reset.service to /lib/systemd/system/reset.service
sudo cp opt/reset.py /opt/reset.py
sudo cp etc/systemd/system/reset.service to /etc/systemd/system/reset.service
chmod 644 /lib/systemd/system/reset.service
systemctl enable reset.service
systemctl start reset.service
This is the software reset schematic. It has a 5v pull-up signal between a 10k resistor.
This WebSDR setup uses one RTL-SDR dongle for two bands (40/80 meters), crontab takes control of which band is working. As wave length isn't the same on both two bands, I'm using a GPiO port to switch between them using a DPDT relay. GPIO3 is controlled by the check_band.sh cron script.
- Ask Pieter to get a copy of WebSDR.
- Copy the websdr-rpi binary and files to your home directory (/home/pi/)
- Edit websdr-80m.cfg and websdr-40m.cfg to fulfill your configuration
- Create Systemd units to manage websdr and rtl_tcp
sudo cp etc/systemd/system/websdr@.service /etc/systemd/system/websdr@.service
sudo cp etc/systemd/system/rtl_tcp@.service /etc/systemd/system/rtl_tcp@.service
- Enable just the rtl_tcp one. Websdr is managed by crontab
sudo systemctl enable rtl_tcp@0.service
- I built a crontab configuration to switch between 40m and 80m bands time-based. Just import the crontab lines into your crontab.
You can always control band changes manual way. Disable cron lines to avoid automatic setup changes. Then you can use
sudo systemctl stop websdr@40.service
sudo systemctl start websdr@40.service
Where 40 is the band you want to receive. You can use and setup almost any band you want, as long as you had setup your websdr-{{band}}m.cfg
I've noticed several websdr nodes that fails to start websdr-rpi using Raspbian. That's due a missing library called libcrypto.
pi@raspberrypi:~/dist11 $ ./websdr-rpi websdr-40m.cfg
./websdr-rpi: error while loading shared libraries: libcrypto.so.1.0.0: cannot open shared object file: No such file or directory
Fix is really easy:
sudo dpkg -i libssl1.0.0_1.0.1t-1+deb8u11_armhf.deb
If your SDR dongle supports direct sampling (such as RTL-SDR.com V3 receiver), there's a way to receive 500khz-28.8mhz without an external upconverter hardware, easing the node build. Install cmake first!
- Unzip rtl-sdr-driver-patched.zip and prepare the environment to build
unzip rtl-sdr-driver-patched.zipcd pkg-rtl-sdr/buildrm *
- Build it
cmake ../ -DINSTALL_UDEV_RULES=ONmakesudo make installsudo ldconfig
Once finished, configure rtl_tcp to use direct sampling mode with the -D 2 switch as follows:
/usr/bin/rtl_tcp -s1024000 -g10 -d0 -p9990 -D2Don't forget to remove theprogfreqline from the websdr configuration file(s).