diff options
Diffstat (limited to 'gr-digital/python/qam.py')
| -rw-r--r-- | gr-digital/python/qam.py | 65 |
1 files changed, 40 insertions, 25 deletions
diff --git a/gr-digital/python/qam.py b/gr-digital/python/qam.py index 5b1f7683b8..8584c59c6f 100644 --- a/gr-digital/python/qam.py +++ b/gr-digital/python/qam.py @@ -27,10 +27,11 @@ from math import pi, sqrt, log from gnuradio import gr from generic_mod_demod import generic_mod, generic_demod +from generic_mod_demod import shared_mod_args, shared_demod_args from utils.gray_code import gray_code from utils import mod_codes import modulation_utils -import digital_swig +import digital_swig as digital # Default number of points in constellation. _def_constellation_points = 16 @@ -157,16 +158,22 @@ def qam_constellation(constellation_points=_def_constellation_points, else: raise ValueError("Mod code is not implemented for QAM") if differential: - points = make_differential_constellation(constellation_points, gray_coded) + points = make_differential_constellation(constellation_points, gray_coded=False) else: points = make_non_differential_constellation(constellation_points, gray_coded) side = int(sqrt(constellation_points)) width = 2.0/(side-1) - # No pre-diff code - # Should add one so that we can gray-code the quadrant bits too. - pre_diff_code = [] - constellation = digital_swig.constellation_rect(points, pre_diff_code, 4, - side, side, width, width) + # For differential and gray-coded then gray-code the first two + # bits with a pre_diff_code. + # FIXME: It would be good to have a test to make sure that gray-coded constellations + # are really gray-coded. Perhaps by checking on the correlation between bit-errors. + if differential and gray_coded: + m = constellation_points + pre_diff_code = range(0, m/2) + range(3*m/4, m) + range(m/2, 3*m/4) + else: + pre_diff_code = [] + constellation = digital.constellation_rect(points, pre_diff_code, 4, + side, side, width, width) return constellation # ///////////////////////////////////////////////////////////////////////////// @@ -174,21 +181,25 @@ def qam_constellation(constellation_points=_def_constellation_points, # ///////////////////////////////////////////////////////////////////////////// class qam_mod(generic_mod): + """ + Hierarchical block for RRC-filtered QAM modulation. + + The input is a byte stream (unsigned char) and the + output is the complex modulated signal at baseband. + + Args: + constellation_points: Number of constellation points (must be a power of four) (integer). + mod_code: Whether to use a gray_code (digital.mod_codes.GRAY_CODE) or not (digital.mod_codes.NO_CODE). + differential: Whether to use differential encoding (boolean). + """ + # See generic_mod for additional arguments + __doc__ += shared_mod_args def __init__(self, constellation_points=_def_constellation_points, differential=_def_differential, mod_code=_def_mod_code, *args, **kwargs): - """ - Hierarchical block for RRC-filtered QAM modulation. - - The input is a byte stream (unsigned char) and the - output is the complex modulated signal at baseband. - - See generic_mod block for list of parameters. - """ - constellation = qam_constellation(constellation_points, differential, mod_code) # We take care of the gray coding in the constellation generation so it doesn't # need to be done in the block. @@ -201,20 +212,24 @@ class qam_mod(generic_mod): # ///////////////////////////////////////////////////////////////////////////// class qam_demod(generic_demod): + """ + Hierarchical block for RRC-filtered QAM modulation. + + The input is a byte stream (unsigned char) and the + output is the complex modulated signal at baseband. + + Args: + constellation_points: Number of constellation points (must be a power of four) (integer). + mod_code: Whether to use a gray_code (digital.mod_codes.GRAY_CODE) or not (digital.mod_codes.NO_CODE). + differential: Whether to use differential encoding (boolean). + """ + # See generic_demod for additional arguments + __doc__ += shared_mod_args def __init__(self, constellation_points=_def_constellation_points, differential=_def_differential, mod_code=_def_mod_code, *args, **kwargs): - - """ - Hierarchical block for RRC-filtered QAM modulation. - - The input is a byte stream (unsigned char) and the - output is the complex modulated signal at baseband. - - See generic_demod block for list of parameters. - """ constellation = qam_constellation(constellation_points, differential, mod_code) # We take care of the gray coding in the constellation generation so it doesn't # need to be done in the block. |