diff options
Diffstat (limited to 'gnuradio-core/src/python/gnuradio/blks2impl/qam.py')
| -rw-r--r-- | gnuradio-core/src/python/gnuradio/blks2impl/qam.py | 113 |
1 files changed, 22 insertions, 91 deletions
diff --git a/gnuradio-core/src/python/gnuradio/blks2impl/qam.py b/gnuradio-core/src/python/gnuradio/blks2impl/qam.py index 22d80503b4..b6096d2cb9 100644 --- a/gnuradio-core/src/python/gnuradio/blks2impl/qam.py +++ b/gnuradio-core/src/python/gnuradio/blks2impl/qam.py @@ -24,13 +24,12 @@ QAM modulation and demodulation. """ from math import pi, sqrt, log -from itertools import islice from gnuradio import gr, gru, modulation_utils2 from gnuradio.blks2impl.generic_mod_demod import generic_mod, generic_demod +from gnuradio.utils.gray_code import gray_code - -# default values (used in __init__ and add_options) +# Default number of points in constellation. _def_constellation_points = 16 def is_power_of_four(x): @@ -48,31 +47,6 @@ def get_bits(x, n, k): # Remove all bits bigger than n+k-1 return v % pow(2, k) -def gray_codes(): - """ Generates gray codes.""" - gcs = [0, 1] - yield 0 - yield 1 - # The last power of two passed through. - lp2 = 2 - # The next power of two that will be passed through. - np2 = 4 - i = 2 - while True: - if i == lp2: - # if i is a power of two then gray number is of form 1100000... - result = i + i/2 - else: - # if not we take advantage of the symmetry of all but the last bit - # around a power of two. - result = gcs[2*lp2-1-i] + lp2 - gcs.append(result) - yield result - i += 1 - if i == np2: - lp2 = i - np2 = i*2 - def make_constellation(m): """ Create a constellation with m possible symbols where m must be @@ -90,7 +64,7 @@ def make_constellation(m): # The quadrant has 'side' points along each side of a quadrant. side = int(sqrtm/2) # Number rows and columns using gray codes. - gcs = list(islice(gray_codes(), side)) + gcs = gray_code(side) # Get inverse gray codes. i_gcs = dict([(v, key) for key, v in enumerate(gcs)]) # The distance between points is found. @@ -125,7 +99,21 @@ def make_constellation(m): const_map.append(get_c(x, y, quad)) return const_map - + + +# ///////////////////////////////////////////////////////////////////////////// +# QAM constellation +# ///////////////////////////////////////////////////////////////////////////// + +def qam_constellation(constellation_points=_def_constellation_points): + """ + Creates a QAM constellation object. + """ + points = make_constellation(constellation_points) + side = int(sqrt(constellation_points)) + width = 2.0/(side-1) + constellation = gr.constellation_sector(points, side, side, width, width) + return constellation # ///////////////////////////////////////////////////////////////////////////// # QAM modulator @@ -141,39 +129,14 @@ class qam_mod(generic_mod): The input is a byte stream (unsigned char) and the output is the complex modulated signal at baseband. - @param m: Number of constellation points. Must be a power of four. - @type m: integer - @param samples_per_symbol: samples per baud >= 2 - @type samples_per_symbol: integer - @param excess_bw: Root-raised cosine filter excess bandwidth - @type excess_bw: float - @param verbose: Print information about modulator? - @type verbose: bool - @param log: Log modulation data to files? - @type log: bool + See generic_mod block for list of parameters. """ if not isinstance(constellation_points, int) or not is_power_of_four(constellation_points): raise ValueError("number of constellation points must be a power of four.") - - points = make_constellation(constellation_points) - side = int(sqrt(constellation_points)) - assert(side * side == constellation_points) - width = 2.0/(side-1) - constellation = gr.constellation_sector(points, side, side, width, width) - #constellation = gr.constellation(points) - + constellation = qam_constellation(constellation_points) super(qam_mod, self).__init__(constellation, *args, **kwargs) - def add_options(parser): - """ - Adds QAM modulation-specific options to the standard parser - """ - parser.add_option("-p", "--constellation-points", type="int", default=_def_constellation_points, - help="set the number of constellation points (must be a power of 4) [default=%default]") - generic_mod.add_options(parser) - add_options=staticmethod(add_options) - # ///////////////////////////////////////////////////////////////////////////// # QAM demodulator # @@ -189,44 +152,12 @@ class qam_demod(generic_demod): The input is a byte stream (unsigned char) and the output is the complex modulated signal at baseband. - @param m: Number of constellation points. Must be a power of four. - @type m: integer - @param samples_per_symbol: samples per symbol >= 2 - @type samples_per_symbol: float - @param excess_bw: Root-raised cosine filter excess bandwidth - @type excess_bw: float - @param freq_alpha: loop filter gain for frequency recovery - @type freq_alpha: float - @param timing_alpha: loop alpha gain for timing recovery - @type timing_alpha: float - @param timing_max_dev: timing loop maximum rate deviations - @type timing_max_dev: float - @param phase_alpha: loop filter gain in phase loop - @type phase_alphas: float - @param verbose: Print information about modulator? - @type verbose: bool - @param debug: Print modualtion data to files? - @type debug: bool + See generic_demod block for list of parameters. """ - points = make_constellation(constellation_points) - side = int(sqrt(constellation_points)) - assert(side * side == constellation_points) - width = 2.0/(side-1) - constellation = gr.constellation_sector(points, side, side, width, width) - #constellation = gr.constellation(points) - + constellation = qam_constellation(constellation_points) super(qam_demod, self).__init__(constellation, *args, **kwargs) - def add_options(parser): - """ - Adds QAM demodulation-specific options to the standard parser - """ - parser.add_option("", "--constellation-points", type="int", default=_def_constellation_points, - help="set the number of constellation points (must be a power of 4) [default=%default]") - generic_demod.add_options(parser) - add_options=staticmethod(add_options) - # # Add these to the mod/demod registry # |