RTL-SDR

RTL-SDR (RTL2832U Software Defined Radio) is a low-cost USB dongle originally designed for digital TV reception that has been repurposed as a wideband software-defined radio. RTL-SDR devices are popular for hobbyist use due to their affordability and wide range of applications.

The RTL-SDR is based on the Realtek RTL2832U chipset, which features direct sampling and demodulation of RF signals. These devices are commonly used for tasks such as listening to FM radio, monitoring aircraft traffic (ADS-B), receiving weather satellite images, and more.

Supported Models

Generic RTL-SDR Dongle: The most common variant, usually featuring an R820T or R820T2 tuner.
RTL-SDR Blog V3: An enhanced version with additional features like direct sampling mode and a bias tee for powering external devices.

Key Features

Frequency Range: Typically from 24 MHz to 1.7 GHz, depending on the tuner chip.
Bandwidth: Limited to about 2.4 MHz, making it suitable for narrowband applications.
Connectivity: USB 2.0 interface, plug-and-play on most platforms.
Software Support: Compatible with SDR software like SDR#, GQRX, and GNU Radio.

Limitations

Narrow bandwidth compared to more expensive SDRs, which may limit some applications.
Sensitivity and performance can vary depending on the specific model and components.
Requires external software for signal processing and analysis.

Set Up Instructions (Linux)

If you previously had RTL-SDR drivers installed, purge them first:

sudo apt purge ^librtlsdr
sudo rm -rvf /usr/lib/librtlsdr*
sudo rm -rvf /usr/include/rtl-sdr*
sudo rm -rvf /usr/local/lib/librtlsdr*
sudo rm -rvf /usr/local/include/rtl-sdr*
sudo rm -rvf /usr/local/include/rtl_*
sudo rm -rvf /usr/local/bin/rtl_*

Install build dependencies:

sudo apt install libusb-1.0-0-dev git cmake pkg-config build-essential

Build librtlsdr from source:

The standard librtlsdr package available via apt is missing symbols required by the Python bindings. Build from the rtl-sdr-blog fork:
Terminal window
```
git clone https://github.com/rtlsdrblog/rtl-sdr-blog.git
cd rtl-sdr-blog
mkdir build && cd build
cmake .. -DINSTALL_UDEV_RULES=ON
make
sudo make install
sudo cp ../rtl-sdr.rules /etc/udev/rules.d/
sudo ldconfig
```
Do not use the osmocom rtl-sdr repository or the Ubuntu librtlsdr-dev apt package. Neither provides the rtlsdr_set_dithering symbol that the Python bindings require.
Blacklist the kernel DVB driver:

The kernel DVB-T driver (dvb_usb_rtl28xxu) claims the RTL-SDR device and prevents librtlsdr from accessing it.

For most users:
Terminal window
```
echo 'blacklist dvb_usb_rtl28xxu' | sudo tee /etc/modprobe.d/blacklist-rtlsdr.conf
sudo modprobe -r dvb_usb_rtl28xxu
```
For Radioconda users, a blacklist configuration is already provided in your conda environment:
Terminal window
```
sudo ln -s $CONDA_PREFIX/etc/modprobe.d/rtl-sdr-blacklist.conf /etc/modprobe.d/radioconda-rtl-sdr-blacklist.conf
sudo modprobe -r $(cat $CONDA_PREFIX/etc/modprobe.d/rtl-sdr-blacklist.conf | sed -n -e 's/^blacklist //p')
```
If modprobe -r fails with “Module is in use”, unplug the RTL-SDR dongle, run the command again, then plug it back in. Alternatively, reboot — the blacklist takes effect on next boot.

Some systems also require blacklisting additional DVB-T modules. Add these entries to your blacklist configuration if needed: rtl2832, rtl2830.

Reload udev rules:

For most users (rules are installed by the build step above):

sudo udevadm control --reload
sudo udevadm trigger

For Radioconda users, create a symlink from your conda environment instead:

sudo ln -s $CONDA_PREFIX/lib/udev/rules.d/rtl-sdr.rules /etc/udev/rules.d/radioconda-rtl-sdr.rules
sudo udevadm control --reload
sudo udevadm trigger

Install Python packages:
Terminal window
```
pip install pyrtlsdr==0.3.0
pip install setuptools==69.5.1
```
pyrtlsdr 0.4.0 references a rtlsdr_set_dithering symbol not present in standard librtlsdr builds. Version 0.3.0 works correctly.
pyrtlsdr 0.3.0 depends on pkg_resources, which was removed in setuptools >= 82. Pinning to 69.5.1 ensures pkg_resources is available.