Hi Marcin, On 22/02/2022 13.09, Marcin Puchlik via GNU Radio, the Free & Open-Source Toolkit for Software Radio wrote: > I also tried to use *low_pass() *function in my C++ program but with no > luck. My linker shouts that there is undefined reference to this function > but headers where recognized.
You need to link your OOT module to gnuradio-filter library - in lib/CMakeLists.txt in target_link_libraries() add gnuradio-filter. target_link_libraries(gnuradio-test gnuradio::gnuradio-runtime gnuradio-filter) Regards, Vasil