Gqrx on Hackberry Pi Zero 2W (NESDR Nano 3)

This guide walks through getting Gqrx SDR running smoothly on a Raspberry Pi Zero 2W Hackberry with a Nooelec NESDR Nano 3 RTL-SDR dongle.

Pre-requisites

Raspberry Pi Zero 2W (Hackberry)
Nooelec NESDR Nano 3 RTL-SDR dongle
Kali Linux (or other Debian-based OS)
Swapfile enabled (2 GB+ recommended)

1. Install required packages

sudo apt update
sudo apt install gqrx-sdr rtl-sdr

2. Verify RTL-SDR detection

lsusb | grep -i realtek
rtl_test -t

You should see the Realtek device detected, and rtl_test should report no major errors.

3. Disable DVB module

sudo rmmod dvb_usb_rtl28xxu
echo 'blacklist dvb_usb_rtl28xxu' | sudo tee /etc/modprobe.d/no-rtl.conf

This prevents the kernel from grabbing the dongle as a DVB device so Gqrx can use it directly.

4. Start PulseAudio

pulseaudio --start

If that fails, try:

pulseaudio --system --disallow-exit --disable-shm

5. Create minimal Gqrx config

mkdir -p ~/.config/gqrx
nano ~/.config/gqrx/default.conf

Paste the following into default.conf:

[General]
rec_dir=/tmp

[Input]
device_args=rtl=0
sample_rate=1024000
freq_corr=0

[Audio]
audio_output_device=None
audio_gain=1
volume=-10

[FFT]
fft_size=512
fft_rate=5
averaging=1
waterfall=0

This keeps Gqrx lightweight enough for the Pi Zero 2W by reducing FFT load and disabling the waterfall.

6. Launch Gqrx

gqrx

First launch may take a bit longer on the Zero 2W. Once it opens, you can refine the settings from the UI.

7. Optimize settings in the UI

File → I/O Devices: set rtl=0, sample rate 1024000, gain around 30 dB.
File → Audio Settings: Output = None if you don't need audio feedback.
Tools → FFT Settings: Size = 256, Rate = 5 fps, Waterfall = Off.

These values keep CPU usage manageable while still giving you a usable spectrum view.

8. Tune to FM

Frequency: 100.1 MHz

If you see “PLL not locked!”, make sure:

Gain is set to a reasonable value (e.g. 30 dB).
Sample rate is low (around 1024000).
You are tuned to a strong local station within the dongle’s range.

Optional: enable swap

swapon --show
sudo dphys-swapfile setup
sudo dphys-swapfile swapon
sudo systemctl enable dphys-swapfile

A 2 GB+ swapfile can help prevent crashes when running heavier GUI applications on the Zero 2W.

You're done

You now have a working SDR setup running Gqrx on a Pi Zero 2W Hackberry with an NESDR Nano 3. From here you can experiment with different modulation modes, frequency ranges, and plugins.