Test for Decode CCSDS 27 degradation bug

testviterbi.py

#!/usr/bin/env python2

import math
import numpy
from gnuradio import gr, digital
from gnuradio import blocks
from gnuradio import fec

# Best to choose powers of 10
N_BITS = 1e8
SKIP = 1000

class BitErrors(gr.hier_block2):
    def __init__(self):
        gr.hier_block2.__init__(self, "BitErrors",
                gr.io_signature(1, 1, gr.sizeof_char),
                gr.io_signature(1, 1, gr.sizeof_int))

        # Bit comparison
        intdump_decim = 100000
        self.connect(self,
                     # skip first samples
                     blocks.skiphead(gr.sizeof_char, SKIP),
                     # exchange 0 <-> 1
                     blocks.not_bb(),
                     blocks.and_const_bb(1),
                     # average over blocks of intdump_decim samples
                     blocks.uchar_to_float(),
                     blocks.integrate_ff(intdump_decim),
                     blocks.multiply_const_ff(1.0/intdump_decim),
                     self)

class BERAWGNSimu(gr.top_block):
    " This contains the simulation flow graph "
    def __init__(self, use_decode_ccsds_27):
        gr.top_block.__init__(self)

        self.sink  = blocks.vector_sink_f()

        descrambler = digital.descrambler_bb(0x21, 0x00, 16)
        add_const = blocks.add_const_ff(-0.5)

        # generate stream of 1's, G3RUH scramble and CC-encode
        self.connect(blocks.vector_source_b([1]*int(N_BITS), False),
                     digital.scrambler_bb(0x21, 0x00, 16),
                     blocks.pack_k_bits_bb(8),
                     fec.encode_ccsds_27_bb(),
                     blocks.uchar_to_float(),
                     add_const)

        if use_decode_ccsds_27:
            # CC-decode with decode_ccsds_27_fb
            self.connect(add_const,
                         fec.decode_ccsds_27_fb(),
                         blocks.unpack_k_bits_bb(8),
                         descrambler)
        else:
            # CC-decode with fec.cc_decoder
            self.connect(add_const,
                         fec.extended_decoder(fec.cc_decoder.make(800, 7, 2, [109, 79]), None),
                         descrambler)

        # G3RUH descrambler and count bit errors
        self.connect(descrambler,
                     digital.descrambler_bb(0x21, 0x00, 16),
                     BitErrors(),
                     self.sink)

if __name__ == "__main__":
    print 'BER with decode_ccsds_27_fb'
    fg = BERAWGNSimu(True)
    fg.run()
    print fg.sink.data()
    print 'BER with fec.cc_decoder'
    fg = BERAWGNSimu(False)
    fg.run()
    print fg.sink.data()