#!/usr/bin/env python
#
# Copyright 2004 Free Software Foundation, Inc.
# 
# This file is part of GNU Radio
# 
# GNU Radio is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.
# 
# GNU Radio is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with GNU Radio; see the file COPYING.  If not, write to
# the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
# Boston, MA 02111-1307, USA.
# 

from gnuradio import gr
from gnuradio import audio

def build_graph ():

	fg = gr.flow_graph ()
        sample_rate = 8000

	src = audio.source (sample_rate)
	out = audio.sink (sample_rate)

	vec1 = [1, -1]
	vsource = gr.vector_source_f (vec1, 1)
	multiply = gr.multiply_ff ()


	fg.connect (src, (multiply, 0))
	fg.connect (vsource, (multiply, 1))
	fg.connect (multiply, out)

	return fg

def main ():
	fg = build_graph()
	fg.start()
	raw_input ('Press Enter to quit')
	fg.stop()


if __name__ == '__main__':
    main ()