[Discuss-gnuradio] FDM

[cswiger]

Not sure if this qualifies as orthonagal or not, but amazingly
data out == data in. The code below gets this frequency spectrum:

http://webpages.charter.net/cswiger/fdm1.jpg

when put into a fft graph, where you can see the 10001101, the pattern
in the vector source. (plot is upmixed with 250Khz to get it all in)

--------------------------

        vec = []
        vec += [ 1, 0, 0, 0, 1, 1, 0, 1]

        src = gr.vector_source_c(vec, 1)
        s2p = gr.serial_to_parallel (gr.sizeof_gr_complex, fft_size)
        ifft1 = gr.fft_vcc (fft_size,False,False) # inverse, no windowing

        p2s = gr.parallel_to_serial (gr.sizeof_gr_complex, fft_size)
        ifft_out = gr.file_sink(gr.sizeof_gr_complex, "ifft")

        fg.connect ( src, s2p )
        fg.connect ( s2p, ifft1 )
        fg.connect ( ifft1, p2s )
        fg.connect ( p2s, ifft_out )


        s2p_2 = gr.serial_to_parallel (gr.sizeof_gr_complex, fft_size)
        fft1_2 = gr.fft_vcc (fft_size,True,False) # forward, no windowing

        p2s_2 = gr.parallel_to_serial (gr.sizeof_gr_complex, fft_size)
        fft_out_2 = gr.file_sink(gr.sizeof_gr_complex, "fft_2")

        fg.connect ( p2s, s2p_2 )
        fg.connect ( s2p_2, fft1_2 )
        fg.connect ( fft1_2, p2s_2 )
        fg.connect ( p2s_2, fft_out_2 )