diff options
| author | Ben Reynwar <ben@reynwar.net> | 2012-04-26 22:57:05 -0700 |
|---|---|---|
| committer | Ben Reynwar <ben@reynwar.net> | 2012-04-26 23:00:19 -0700 |
| commit | 084249788afd57ffa5e56e699f25cc0e2d6f5616 (patch) | |
| tree | 049534e25d68011d248d0687d02c1263571f0d60 /gr-digital/python/psk.py | |
| parent | 93940233c63b1e889a502dc0558de2bc03bab414 (diff) | |
gr-digital: PSK modulation. Gray-coding done by constellation order for non-differential modulation.
Diffstat (limited to 'gr-digital/python/psk.py')
| -rw-r--r-- | gr-digital/python/psk.py | 29 |
1 files changed, 19 insertions, 10 deletions
diff --git a/gr-digital/python/psk.py b/gr-digital/python/psk.py index 58f6787f0c..4b35447278 100644 --- a/gr-digital/python/psk.py +++ b/gr-digital/python/psk.py @@ -35,17 +35,23 @@ from generic_mod_demod import generic_mod, generic_demod _def_constellation_points = 4 # The default encoding (e.g. gray-code, set-partition) _def_mod_code = mod_codes.GRAY_CODE +# Default use of differential encoding +_def_differential = True -def create_encodings(mod_code, arity): +def create_encodings(mod_code, arity, differential): post_diff_code = None if mod_code not in mod_codes.codes: raise ValueError('That modulation code does not exist.') if mod_code == mod_codes.GRAY_CODE: - pre_diff_code = gray_code.gray_code(arity) - elif mod_code == mod_codes.SET_PARTITION_CODE: - pre_diff_code = set_partition_code.set_partition_code(arity) + if differential: + pre_diff_code = gray_code.gray_code(arity) + post_diff_code = None + else: + pre_diff_code = [] + post_diff_code = gray_code.gray_code(arity) elif mod_code == mod_codes.NO_CODE: pre_diff_code = [] + post_diff_code = None else: raise ValueError('That modulation code is not implemented for this constellation.') return (pre_diff_code, post_diff_code) @@ -54,7 +60,8 @@ def create_encodings(mod_code, arity): # PSK constellation # ///////////////////////////////////////////////////////////////////////////// -def psk_constellation(m=_def_constellation_points, mod_code=_def_mod_code): +def psk_constellation(m=_def_constellation_points, mod_code=_def_mod_code, + differential=_def_differential): """ Creates a PSK constellation object. """ @@ -62,7 +69,7 @@ def psk_constellation(m=_def_constellation_points, mod_code=_def_mod_code): if (k != int(k)): raise StandardError('Number of constellation points must be a power of two.') points = [exp(2*pi*(0+1j)*i/m) for i in range(0,m)] - pre_diff_code, post_diff_code = create_encodings(mod_code, m) + pre_diff_code, post_diff_code = create_encodings(mod_code, m, differential) if post_diff_code is not None: inverse_post_diff_code = mod_codes.invert_code(post_diff_code) points = [points[x] for x in inverse_post_diff_code] @@ -77,6 +84,7 @@ class psk_mod(generic_mod): def __init__(self, constellation_points=_def_constellation_points, mod_code=_def_mod_code, + differential=_def_differential, *args, **kwargs): """ @@ -88,8 +96,8 @@ class psk_mod(generic_mod): See generic_mod block for list of parameters. """ - constellation = psk_constellation(constellation_points, mod_code) - super(psk_mod, self).__init__(constellation, *args, **kwargs) + constellation = psk_constellation(constellation_points, mod_code, differential) + super(psk_mod, self).__init__(constellation, differential, *args, **kwargs) # ///////////////////////////////////////////////////////////////////////////// # PSK demodulator @@ -100,6 +108,7 @@ class psk_demod(generic_demod): def __init__(self, constellation_points=_def_constellation_points, mod_code=_def_mod_code, + differential=_def_differential, *args, **kwargs): """ @@ -111,8 +120,8 @@ class psk_demod(generic_demod): See generic_demod block for list of parameters. """ - constellation = psk_constellation(constellation_points, mod_code) - super(psk_demod, self).__init__(constellation, *args, **kwargs) + constellation = psk_constellation(constellation_points, mod_code, differential) + super(psk_demod, self).__init__(constellation, differential, *args, **kwargs) # # Add these to the mod/demod registry |