I am trying to implement ofdm using grc blocks. I am getting an error in insert preamble block saying
TypeError: in method 'ofdm_insert_preamble', argument 2 of type 'std::vector< std::vector< gr_complex,std::allocator< gr_complex > >,std::allocator< std::vector< gr_complex,std::allocator< gr_complex > > > > const &
I have attached the grc file. what should i give as input to flag input of insert preamble block and also how to connect the output flag of insert preamble block. How does that flag work in the block.