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#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @file
# @author (C) 2015 by Roman Khassraf <rkhassraf@gmail.com>
# (C) 2017 by Piotr Krysik <ptrkrysik@gmail.com>
# @section LICENSE
#
# Gr-gsm 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.
#
# Gr-gsm 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 gr-gsm; see the file COPYING. If not, write to
# the Free Software Foundation, Inc., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
#
#
import collections
__chan_spacing = 2e5
__arfcn_pcs = 0x8000
# first uplink freq, distance between uplink/downlink frequency, list of range tuple
# each tuple in a range tuple contains: first arfcn of the range, last arfcn of the range, offset of the range
# entries are ordered by relevance
__band_conf = collections.OrderedDict([
('GSM900', {'f_start': 880.2e6, 'distance': 45e6, 'ranges': [(975, 1023), (0, 124)]}),
('DCS1800', {'f_start': 1710.2e6, 'distance': 95e6, 'ranges': [(512, 885)]}),
('GSM850', {'f_start': 824.2e6, 'distance': 45e6, 'ranges': [(128, 251)]}),
('PCS1900', {'f_start': 1850.2e6, 'distance': 80e6, 'ranges': [(512+__arfcn_pcs, 810+__arfcn_pcs)]}), #PCS band is "special" as its channel number range overlap with DCS1800
('GSM450', {'f_start': 450.6e6, 'distance': 10e6, 'ranges': [(259, 293)]}),
('GSM480', {'f_start': 479e6, 'distance': 10e6, 'ranges': [(306, 340)]}),
('GSM-R', {'f_start': 876.2e6, 'distance': 45e6, 'ranges': [(955, 1023), (0, 124)]}),
])
def get_bands():
return __band_conf.keys()
def arfcn2band(arfcn):
for band_name,band_desc in __band_conf.items():
for arfcns_range in band_desc["ranges"]:
arfcn_start = arfcns_range[0]
arfcn_stop = arfcns_range[1]
if arfcn_start <= arfcn <= arfcn_stop:
return band_name
return None
def freq2band(freq, downlink=False):
for band_name,band_desc in __band_conf.items():
chans_total = 0
#count total number of channels in the range
for arfcns_range in band_desc["ranges"]:
arfcn_start = arfcns_range[0]
arfcn_stop = arfcns_range[1]
chans_in_range = arfcn_stop - arfcn_start + 1
chans_total = chans_total + chans_in_range
first_freq = band_desc["f_start"]
if downlink:
first_freq = first_freq + band_desc["distance"]
last_freq = first_freq + (chans_total - 1) * __chan_spacing
if first_freq <= freq <= last_freq:
return band_name
return None
def uplink2band(freq):
return freq2band(freq, False)
def downlink2band(freq):
return freq2band(freq, True)
def is_valid_arfcn(arfcn):
"""
Returns True if arfcn is valid in the given band, else False
"""
band = arfcn2band(arfcn)
if band is not None:
conf = __band_conf.get(band)
for arfcn_range in conf['ranges']:
arfcn_start = arfcn_range[0]
arfcn_end = arfcn_range[1]
if arfcn_start <= arfcn <= arfcn_end:
return True
return False
def is_valid_uplink(freq):
"""
Returns True if the given frequency is a valid uplink frequency in the given band
"""
result = False
band = uplink2band(freq)
if band is not None:
result = True
return result
def is_valid_downlink(freq):
"""
Returns True if the given frequency is a valid downlink frequency in the given band
"""
result = False
band = downlink2band(freq)
if band is not None:
result = True
return result
def arfcn2uplink(arfcn):
band = arfcn2band(arfcn)
if band is not None:
conf = __band_conf.get(band)
f_start = conf['f_start']
arfcns_total = 0
for arfcn_range in conf['ranges']:
arfcn_start = arfcn_range[0]
arfcn_end = arfcn_range[1]
if arfcn_start <= arfcn <= arfcn_end:
f = f_start + (__chan_spacing * (arfcn - arfcn_start + arfcns_total))
return round(f, 1)
arfcns_total = arfcn_end - arfcn_start + 1
return -1
def arfcn2downlink(arfcn):
band = arfcn2band(arfcn)
if band is not None:
conf = __band_conf.get(band)
distance = conf['distance']
return round(arfcn2uplink(arfcn) + distance, 1)
return -1
def uplink2arfcn(freq):
band = uplink2band(freq)
if band is not None:
conf = __band_conf.get(band)
arfcns_total = 0
for arfcn_range in conf['ranges']:
arfcn_start = arfcn_range[0]
arfcn_end = arfcn_range[1]
arfcns_in_range = arfcn_end - arfcn_start + 1
freq_start = conf['f_start'] + arfcns_total * __chan_spacing
freq_end = freq_start + (arfcns_in_range - 1) * __chan_spacing
if freq_start <= freq <= freq_end:
arfcn = int(round(arfcn_start + ((freq - freq_start) / __chan_spacing), 0))
return arfcn
arfcns_total = arfcns_total + arfcns_in_range
return -1
def downlink2arfcn(freq):
band = downlink2band(freq)
if band is not None:
conf = __band_conf.get(band)
distance = conf['distance']
freq_uplink = freq - distance
return int(round(uplink2arfcn(freq_uplink), 0))
return -1
def get_arfcn_ranges(band):
"""
Returns a list of arfcn tuples, each with first and last arfcn of the range.
"""
result = []
if band in __band_conf:
conf = __band_conf.get(band)
for arfcn_range in conf['ranges']:
arfcn_tuple = (arfcn_range[0], arfcn_range[1])
result.append(arfcn_tuple)
return result
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