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#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Copyright 2021 Sara Cinzia Halter.
#
# This 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.
#
# This software 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 this software; see the file COPYING. If not, write to
# the Free Software Foundation, Inc., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
#
import numpy as np
from numpy.fft import fft,ifft,fftshift
from gnuradio import gr
from fadingui.logger import get_logger
log = get_logger("multipath_fading")
class multipath_fading(gr.sync_block):
"""
docstring for block multipath_fading
"""
def __init__(self, amplitudes, delays, los):
gr.sync_block.__init__(
self,
name='Multipath fading',
in_sig=[np.complex64],
out_sig=[np.complex64]
)
if len(amplitudes) != len(delays):
raise Exception("Amplitudes and Delay length dont match")
if np.min(delays) < 0:
raise Exception("Delay can't be negative")
self.amplitudes = amplitudes
self.delays = delays
self.temp = [0]
self.los = 1 if los else 0
def work(self, input_items, output_items):
inp = input_items[0]
oup = output_items[0]
max_order = 2 * np.floor(np.max(self.delays)) + 1
max_samples = np.arange(0, max_order +1)
max_len = len(max_samples)
tot_h = np.zeros(int(max_len))
for (a, d) in zip(self.amplitudes, self.delays):
order = 2 * np.floor(d) + 1
samples = np.arange(0, order +1)
# compute FIR
h = a * np.sinc(samples - d)
# adjust length
h = np.concatenate([h, np.zeros(max_len - len(h))])
tot_h += h
tot_h[0] += self.los
# compute output and add rest from last block processing
y = np.convolve(inp, tot_h)
y += np.concatenate([self.temp, np.zeros(len(y) - len(self.temp))])
# write output
oup[:] = y[:len(inp)]
# save for next block processing
self.temp = y[len(inp):]
return len(oup)
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