On Mon, Sep 10, 2012 at 5:50 PM, Joana Goncalves <[email protected]> wrote: > Hello, > > I am quite new in GnuRadio Companion and I am just trying to transmit and > receive a file through FSK modulation, but I am having some troubles. > > Attached is the block diagram that I am trying to implement. Do you know > what is the problem here? > > I don’t understand very well some block and how they work, such as the > Chunks to symbols and Interpolating FIR FILTER. Can you give me a help? > > > > Thank you very much for your help. > > Best regards > Joana
Joana, The chunks_to_symbols is a mapping block. It takes in a byte and converts that to the set of symbols defined by the block. Basically, the block takes in as its 'Symbol Table' argument a vector of complex numbers, call this sym_table. The input stream to this block will be bytes, and those bytes are mapped to the complex symbols in sym_table directly. So if the input value is 0, the output is sym_table[0]; if the input is 3, the output is sym_table[3]. That also means that your symbol table should be as large as the input value "chunks" are expected to be. The interpolating filter is a rate conversion filter. It interpolates a signal and then filters it to remove the images generated from the filtering. You definitely don't want the taps of the filter to be all 1's; that won't filter out anything. You can use the 'gr.firdes' or 'gr.optfir' modules to build the filters for you. Remember that when building a filter for the interpolator, make sure you specify the sample rate as the sample rate /after/ the interpolation. Tom _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
