Hello, My system config: OS: Ubuntu 20.04.3 LTS OS Type: 64-bit RAM: 3.8 GB Processor: Intel Core i5-2450M CPU @2.50GHz x4 UHD version: 3.15.0.0 GNU Radio version: 3.8.1.0 SDR Device: Ettus USRP N320 Antenna Freq: 868 MHz I tried to build osmocom block in my existing gnuradio environment, but I got the following error during cmake command. The console logs are shown below. Console logs: komro@komro-HP-ProBook-6560b:~/gnuradio/gr-osmosdr/build$ cmake ../ -- The CXX compiler identification is GNU 9.3.0 -- The C compiler identification is GNU 9.3.0 -- Check for working CXX compiler: /usr/bin/c++ -- Check for working CXX compiler: /usr/bin/c++ -- works -- Detecting CXX compiler ABI info -- Detecting CXX compiler ABI info - done -- Detecting CXX compile features -- Detecting CXX compile features - done -- Check for working C compiler: /usr/bin/cc -- Check for working C compiler: /usr/bin/cc -- works -- Detecting C compiler ABI info -- Detecting C compiler ABI info - done -- Detecting C compile features -- Detecting C compile features - done -- Build type not specified: defaulting to release. -- Found Git: /usr/bin/git (found version "2.25.1") -- Extracting version information from git describe... -- Configuring Boost C++ Libraries... -- Found Boost: /usr/lib/x86_64-linux-gnu/cmake/Boost-1.71.0/BoostConfig.cmake (found version "1.71.0") found components: thread system -- Found PkgConfig: /usr/bin/pkg-config (found version "0.29.1") -- Checking for module 'gruel' -- No package 'gruel' found -- Could NOT find GRUEL (missing: GRUEL_LIBRARIES GRUEL_INCLUDE_DIRS) -- Checking for module 'gnuradio-core' -- No package 'gnuradio-core' found -- Could NOT find GNURADIO_CORE (missing: GNURADIO_CORE_LIBRARIES GNURADIO_CORE_INCLUDE_DIRS) -- Checking for module 'gnuradio-iqbalance' -- No package 'gnuradio-iqbalance' found -- Could NOT find GNURADIO_IQBALANCE (missing: GNURADIO_IQBALANCE_LIBRARIES GNURADIO_IQBALANCE_INCLUDE_DIRS) -- Checking for module 'uhd' -- No package 'uhd' found -- Could NOT find UHD (missing: UHD_LIBRARIES UHD_INCLUDE_DIRS) -- Checking for module 'gnuradio-uhd' -- Found gnuradio-uhd, version 3.8.1 -- gnuradio-uhd not found. -- Could NOT find GNURADIO_UHD (missing: GNURADIO_UHD_INCLUDE_DIRS) -- Checking for module 'gnuradio-fcd' -- No package 'gnuradio-fcd' found -- gnuradio-fcd not found. -- Could NOT find GNURADIO_FCD (missing: GNURADIO_FCD_LIBRARIES GNURADIO_FCD_INCLUDE_DIRS) -- Checking for module 'gnuradio-fcdproplus' -- No package 'gnuradio-fcdproplus' found -- gnuradio-fcdproplus not found. -- Could NOT find GNURADIO_FCDPP (missing: GNURADIO_FCDPP_LIBRARIES GNURADIO_FCDPP_INCLUDE_DIRS) -- Checking for module 'libosmosdr' -- No package 'libosmosdr' found -- libosmosdr not found. -- Checking for module 'librtlsdr' -- Found librtlsdr, version 0.6.0-32-gd770 -- Found librtlsdr: /usr/local/include, /usr/local/lib/librtlsdr.so -- Checking for module 'libmirisdr' -- No package 'libmirisdr' found -- libmirisdr not found. -- Checking for module 'libhackrf' -- No package 'libhackrf' found -- Could NOT find LIBHACKRF (missing: LIBHACKRF_LIBRARIES LIBHACKRF_INCLUDE_DIRS) -- Checking for module 'libairspy' -- No package 'libairspy' found -- Could NOT find LIBAIRSPY (missing: LIBAIRSPY_LIBRARIES LIBAIRSPY_INCLUDE_DIRS) -- Checking for module 'libbladeRF' -- No package 'libbladeRF' found -- libbladeRF not found. -- Found Doxygen: /usr/bin/doxygen (found version "1.8.17") found components: doxygen missing components: dot CMake Error at CMakeLists.txt:166 (message): Gruel required to build gr-osmosdr -- Configuring incomplete, errors occurred! See also "/home/komro/gnuradio/gr-osmosdr/build/CMakeFiles/CMakeOutput.log". See also "/home/komro/gnuradio/gr-osmosdr/build/CmakeFiles/CmakeError.log". What am I missing here? I installed the required RTL-SDR packages too! PFA CMake files Best regards, Thangaraj