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#!/usr/bin/env python
#
# Copyright 2008 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 3, 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., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
#
from gnuradio import gr
from math import pi, log10
import cmath
class transmit_path(gr.hier_block2):
"""
This transmits a BERT sequence of bits using filtered BPSK and
outputs the complex baseband waveform.
"""
def __init__(self,
sps, # Samples per symbol
excess_bw, # RRC filter excess bandwidth (typically 0.35-0.5)
amplitude # DAC output level, 0-32767, typically 2000-8000
):
gr.hier_block2.__init__(self, "transmit_path",
gr.io_signature(0, 0, 0), # Input signature
gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature
# Create BERT data bit stream
self._bits = gr.vector_source_b([1,], True) # Infinite stream of ones
self._scrambler = gr.scrambler_bb(0x8A, 0x7F, 7) # CCSDS 7-bit scrambler
# Map to constellation
self._constellation = [-1+0j, 1+0j]
self._mapper = gr.chunks_to_symbols_bc(self._constellation)
# Create RRC with specified excess bandwidth
taps = gr.firdes.root_raised_cosine(sps*amplitude, # Gain
sps, # Sampling rate
1.0, # Symbol rate
excess_bw, # Roll-off factor
11*sps) # Number of taps
self._rrc = gr.interp_fir_filter_ccf(sps, # Interpolation rate
taps) # FIR taps
# Wire block inputs and outputs
self.connect(self._bits, self._scrambler, self._mapper, self._rrc, self)
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