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