Subject: Raspberry Pi 5 + RTL-SDR Blog V4 – rtl_* CLI tools produce zero
output
Dear Developers,
I would like to report a reproducible issue observed with a Raspberry Pi 5
and an RTL-SDR Blog V4 device.
*Hardware setup:*
Raspberry Pi 5 (8 GB)
RTL-SDR Blog V4
Direct USB connection (no external hub)
Adequate power supply (official Raspberry Pi 5 power supply)
*Software environment:*
Raspberry Pi OS 64-bit (Bookworm)
rtl-sdr package (rtl_sdr, rtl_fm, rtl_power)
librtlsdr installed via distribution packages
Fully updated kernel and system
*Issue description:*
rtl_test -p runs successfully
USB streaming is active and samples are reported
PLL lock messages are shown and the device appears stable
*However, the following CLI tools produce no output data:*
rtl_sdr
rtl_fm
rtl_power
Output files remain at 0 bytes
Processes run without errors, but no IQ samples or audio data are produced
*Important observation:*
The same RTL-SDR Blog V4 device works correctly on Raspberry Pi 3 and
Raspberry Pi 4 systems using the same software stack.
*Conclusion:*
Based on testing, this appears to be an interaction issue between the
Raspberry Pi 5 USB subsystem and/or kernel, librtlsdr, and the RTL-SDR Blog
V4. Since rtl_test confirms that USB streaming is functional, the problem
seems to occur at the level of sample delivery or processing in the CLI
tools.
I am happy to provide logs, detailed version information, or perform
additional tests if required.
Thank you for your time and for maintaining these tools.
Kind regards,
An RTL-SDR user
P.S.
My original goal was to develop an Airband (voice) scanner application with
the help of ChatGPT, capable of scanning and monitoring airband
frequencies. Neither the RTL-SDR Blog V3 nor the V4 worked as expected on
the Raspberry Pi 5 during this effort.
Based on recommendations, I specifically purchased an RTL-SDR Blog V4
because it was expected to be better aligned with the Raspberry Pi 5 USB
implementation.
This report is the result of several days of systematic testing and
comparison across different Raspberry Pi models.
The device enumerates correctly on USB and remains stable during operation.
rtl_test confirms continuous sample streaming, indicating that bulk USB
transfers are functional.
No kernel errors, USB resets, or xHCI faults are observed in dmesg during
runtime.
The issue appears after device initialization, at the stage where
librtlsdr-based tools should consume and process the incoming samples.
USB-related kernel and firmware boot parameters were reviewed and adjusted
via /boot/firmware/cmdline.txt, including settings related to USB behavior
and buffering; these changes did not alter the observed issue.
This suggests a possible interaction issue between the Raspberry Pi 5
USB/xHCI implementation, kernel behavior, and librtlsdr buffer handling
rather than a physical USB or power problem
uname -a
lsusb
lsusb -t
dmesg | grep -i usb
rtl_test -p
rtl_sdr test.iq
rtl_fm -f 118M -M am -s 240k -
rtl_power -f 118M:137M:25k test.csv
I did not purchase the Raspberry Pi 5 and the RTL-SDR Blog V4 as
experimental or disposable hardware. This report is submitted in good
faith, with the expectation that this platform can be made fully functional
through proper investigation and resolution
