Raspberry Pi as a Remote SDR reciever

Having recently renewed my amateur radio licence, I decided it was time to see what I could do with a Raspberry Pi. You can now get software defined radios for incredibly low prices as use these for all sorts of things, one of these is for use as a receiver. You can simply buy one, plug it into a USB socket on your desktop, download sdrsharp and away you go, you do then need to connect the antenna to the USB device and this could result in a long run of cable.

Alternatively, you can connect the USB device to a Raspberry Pi, install some software, put the Pi outside in a waterproof box and connect via ethernet or wirelessly. I've gone for this option and used a wireless connection.

I've gone for the setup shown below, picked up from Amazon.

I'm also using a Raspberry Pi model 3 as it has built in wifi, you can use a 2 with a USB dongle or a 4 if you want.

Once all the stuff is together, it's time to get started. Connect to your Pi via ssh and run the following.

sudo apt update 

sudo apt upgrade -y 

sudo shutdown -r now

sudo apt-get install -y  git cmake  libusb-1.0-0-dev mc

git clone git://git.osmocom.org/rtl-sdr.git

Now we build the RTL SDR package.

cd rtl-sdr

mkdir build

cd build

cmake ../ -DINSTALL_UDEV_RULES=ON

make

sudo make install

sudo cp ../rtl-sdr.rules /etc/udev/rules.d/

sudo ldconfig

sudo nano /etc/udev/rules.d/rtl-sdr.rules

At the top of the file you will see this, change the 0660 to 0666 in both cases.

# original RTL2832U vid/pid (hama nano, for example)

SUBSYSTEMS=="usb", ATTRS{idVendor}=="0bda", ATTRS{idProduct}=="2832", ENV{ID_SOFTWARE_RADIO}="1", MODE="0660", GROUP="plugdev"

# RTL2832U OEM vid/pid, e.g. ezcap EzTV668 (E4000), Newsky TV28T (E4000/R820T) etc.

SUBSYSTEMS=="usb", ATTRS{idVendor}=="0bda", ATTRS{idProduct}=="2838", ENV{ID_SOFTWARE_RADIO}="1", MODE="0660", GROUP="plugdev"

It should now look like this.

# original RTL2832U vid/pid (hama nano, for example)

SUBSYSTEMS=="usb", ATTRS{idVendor}=="0bda", ATTRS{idProduct}=="2832", ENV{ID_SOFTWARE_RADIO}="1", MODE="0666", GROUP="plugdev"

# RTL2832U OEM vid/pid, e.g. ezcap EzTV668 (E4000), Newsky TV28T (E4000/R820T) etc.

SUBSYSTEMS=="usb", ATTRS{idVendor}=="0bda", ATTRS{idProduct}=="2838", ENV{ID_SOFTWARE_RADIO}="1", MODE="0666", GROUP="plugdev"

sudo nano /etc/modprobe.d/blacklist-rtl.conf

Paste this and and save and exit

blacklist dvb_usb_rtl28xxu

blacklist rtl2832

blacklist rtl2830

Now run the following

sudo apt-get install libvolk2-bin -y

volk_profile

This will take some time

Last thing to do is get the software to run at start up, I'm going to create a service to get this started on boot, we also need to provide the IP address that the pi is running at to the command line to get it running.

Let's create a file with sudo nano /bin/sdrstart

Paste this into the file.

#!/bin/bash

# Sets the variable $_IP as the ip address

_IP=$(hostname -I)

# Runs the rtl_tcp app and provides the output to it's own ip.

rtl_tcp -a $_IP

Make the file executable with sudo chmod +x /bin/sdrstart

Now we create a file for the service with sudo nano /etc/systemd/system/rtl.service

Paste this into the file.

[Unit]

Description SDR Start

After=network-online.target

[Service]

[Unit]

Description SDR Start

Wants=network-online.target

After=network-online.target

[Service]

Type=simple

ExecStart=/bin/bash /bin/sdrstart

PermissionStartOnly=true

StandardOutput=null

User=root

[Install]

WantedBy=multi-user.target

Save it and then run

sudo systemctl daemon-reload

sudo systemctl enable rtl.service

sudo service rtl restart

If you then run sudo service rtl status, you should see your Pi reporting that it's all up and running.

Give it a restart and you should be able to connect sdrsharp to the Pi using the RTL_SDR TCP option.

Thanks to Mike Richards G4WNC for the initial article and a lot of searching to fix a few little issues.