python/trx/radio_if.py

#!/usr/bin/env python2
# -*- coding: utf-8 -*-

# GR-GSM based transceiver
# Follow graph implementation
#
# (C) 2016-2018 by Vadim Yanitskiy <axilirator@gmail.com>
# (C) 2017      by Piotr Krysik <ptrkrysik@gmail.com>
#
# All Rights Reserved
#
# This program 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 2 of the License, or
# (at your option) any later version.
#
# This program 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 program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

import pmt
import time
import grgsm

from math import pi

from gnuradio import eng_notation
from gnuradio import digital
from gnuradio import blocks
from gnuradio import uhd
from gnuradio import gr

from gnuradio import filter
from gnuradio.filter import firdes


# HACK: should be implemented in C++!
class dict_toggle_sign(gr.basic_block):
    def __init__(self):  # only default arguments here
        gr.basic_block.__init__(self,
            name='Change sign of elts in dict',
            in_sig=[],
            out_sig=[]
        )
        self.message_port_register_in(pmt.intern("dict_in"))
        self.message_port_register_out(pmt.intern("dict_out"))
        self.set_msg_handler(pmt.intern("dict_in"), self.change_sign)

    def change_sign(self, msg):
        if pmt.is_dict(msg):
            d = pmt.to_python(msg)
            for key, value in d.items():
                d[key] *= -1
            self.message_port_pub(pmt.intern("dict_out"), pmt.to_pmt(d))

class radio_if(gr.top_block):
  # PHY specific variables
  rx_freq = 935e6
  tx_freq = 890e6
  osr = 4

  # Application state flags
  trx_started = False

  # GSM timings (in microseconds [uS])
  # One timeslot duration is 576.9 μs = 15/26 ms,
  # or 156.25 symbol periods (a symbol period is 48/13 μs)
  GSM_SYM_PERIOD_uS = 48.0 / 13.0
  GSM_TS_PERIOD_uS = GSM_SYM_PERIOD_uS * 156.25
  GSM_UL_DL_SHIFT_uS = -(GSM_TS_PERIOD_uS * 3)

  # FIXME: shall be measured (automatically?) for
  # particular device and particular clock rate.
  # The current value is measured for USRP B2X0 at 26e6.
  delay_correction = (285.616 + 2 * GSM_SYM_PERIOD_uS) * 1e-6

  def __init__(self, phy_args, phy_sample_rate,
      phy_rx_gain, phy_tx_gain, phy_ppm,
      phy_rx_antenna, phy_tx_antenna,
      phy_freq_offset,
      trx_bind_addr, trx_remote_addr,
      trx_base_port):

    print("[i] Init Radio interface (L:%s:%u <-> R:%s:%u)"
      % (trx_bind_addr, trx_base_port + 2,
        trx_remote_addr, trx_base_port + 102))

    # PHY specific variables
    self.sample_rate = phy_sample_rate
    self.rx_gain = phy_rx_gain
    self.tx_gain = phy_tx_gain
    self.phy_freq_offset = phy_freq_offset
    self.ppm = phy_ppm

    gr.top_block.__init__(self, "GR-GSM TRX")

    # TRX Burst Interface
    self.trx_burst_if = grgsm.trx_burst_if(
      trx_bind_addr, trx_remote_addr,
      str(trx_base_port))

    # RX path definition
    self.phy_src = uhd.usrp_source(phy_args,
      uhd.stream_args(cpu_format="fc32",
        channels=range(1)))

    self.phy_src.set_clock_rate(26e6, uhd.ALL_MBOARDS)
    self.phy_src.set_center_freq(self.rx_freq, 0)
    self.phy_src.set_antenna(phy_rx_antenna, 0)
    self.phy_src.set_samp_rate(phy_sample_rate)
    self.phy_src.set_bandwidth(650e3, 0)
    self.phy_src.set_gain(phy_rx_gain)

    self.msg_to_tag_src = grgsm.msg_to_tag()

    self.rotator_src = grgsm.controlled_rotator_cc(
      self.calc_phase_inc(self.rx_freq))

    self.lpf = filter.fir_filter_ccf(1, firdes.low_pass(
      1, phy_sample_rate, 125e3, 5e3, firdes.WIN_HAMMING, 6.76))

    self.gsm_receiver = grgsm.receiver(self.osr, ([0]), ([]))

    self.ts_filter = grgsm.burst_timeslot_filter(0)
    self.ts_filter.set_policy(grgsm.FILTER_POLICY_DROP_ALL)

    # Connections
    self.connect(
      (self.phy_src, 0),
      (self.msg_to_tag_src, 0))

    self.connect(
      (self.msg_to_tag_src, 0),
      (self.rotator_src, 0))

    self.connect(
      (self.rotator_src, 0),
      (self.lpf, 0))

    self.connect(
      (self.lpf, 0),
      (self.gsm_receiver, 0))

    self.msg_connect(
      (self.gsm_receiver, 'C0'),
      (self.ts_filter, 'in'))

    self.msg_connect(
      (self.ts_filter, 'out'),
      (self.trx_burst_if, 'bursts'))


    # TX Path Definition
    self.phy_sink = uhd.usrp_sink(phy_args,
      uhd.stream_args(cpu_format="fc32",
        channels=range(1)), "packet_len")

    self.phy_sink.set_clock_rate(26e6, uhd.ALL_MBOARDS)
    self.phy_sink.set_antenna(phy_tx_antenna, 0)
    self.phy_sink.set_samp_rate(phy_sample_rate)
    self.phy_sink.set_center_freq(self.tx_freq, 0)
    self.phy_sink.set_gain(self.tx_gain)

    self.tx_time_setter = grgsm.txtime_setter(
      0xffffffff, 0, 0, 0, 0, 0,
      self.delay_correction + self.GSM_UL_DL_SHIFT_uS * 1e-6)

    self.tx_burst_proc = grgsm.preprocess_tx_burst()

    self.pdu_to_tagged_stream = blocks.pdu_to_tagged_stream(
      blocks.byte_t, 'packet_len')

    self.gmsk_mod = grgsm.gsm_gmsk_mod(
      BT = 0.3, pulse_duration = 4, sps = self.osr)

    self.burst_shaper = digital.burst_shaper_cc(
      (firdes.window(firdes.WIN_HANN, 16, 0)),
      0, 20, False, "packet_len")

    self.msg_to_tag_sink = grgsm.msg_to_tag()

    self.rotator_sink = grgsm.controlled_rotator_cc(
      -self.calc_phase_inc(self.tx_freq))

    # Connections
    self.msg_connect(
      (self.trx_burst_if, 'bursts'),
      (self.tx_time_setter, 'bursts_in'))

    self.msg_connect(
      (self.tx_time_setter, 'bursts_out'),
      (self.tx_burst_proc, 'bursts_in'))

    self.msg_connect(
      (self.tx_burst_proc, 'bursts_out'),
      (self.pdu_to_tagged_stream, 'pdus'))

    self.connect(
      (self.pdu_to_tagged_stream, 0),
      (self.gmsk_mod, 0))

    self.connect(
      (self.gmsk_mod, 0),
      (self.burst_shaper, 0))

    self.connect(
      (self.burst_shaper, 0),
      (self.msg_to_tag_sink, 0))

    self.connect(
      (self.msg_to_tag_sink, 0),
      (self.rotator_sink, 0))

    self.connect(
      (self.rotator_sink, 0),
      (self.phy_sink, 0))


    # RX & TX synchronization
    self.bt_filter = grgsm.burst_type_filter([3])
    self.burst_to_fn_time = grgsm.burst_to_fn_time()

    # Connections
    self.msg_connect(
      (self.gsm_receiver, 'C0'),
      (self.bt_filter, 'bursts_in'))

    self.msg_connect(
      (self.bt_filter, 'bursts_out'),
      (self.burst_to_fn_time, 'bursts_in'))

    self.msg_connect(
      (self.burst_to_fn_time, 'fn_time_out'),
      (self.tx_time_setter, 'fn_time'))


    # AFC (Automatic Frequency Correction)
    self.gsm_clck_ctrl = grgsm.clock_offset_control(
      self.rx_freq, phy_sample_rate, osr = self.osr)

    self.dict_toggle_sign = dict_toggle_sign()

    # Connections
    self.msg_connect(
      (self.gsm_receiver, 'measurements'),
      (self.gsm_clck_ctrl, 'measurements'))

    self.msg_connect(
      (self.gsm_clck_ctrl, 'ctrl'),
      (self.msg_to_tag_src, 'msg'))

    self.msg_connect(
      (self.gsm_clck_ctrl, 'ctrl'),
      (self.dict_toggle_sign, 'dict_in'))

    self.msg_connect(
      (self.dict_toggle_sign, 'dict_out'),
      (self.msg_to_tag_sink, 'msg'))


    # Some UHD devices (such as UmTRX) do start the clock
    # not from 0, so it's required to reset it manually.
    # Resetting UHD source will also affect the sink.
    self.phy_src.set_time_now(uhd.time_spec(0.0))

  def shutdown(self):
    print("[i] Shutdown Radio interface")
    self.stop()
    self.wait()

  def calc_phase_inc(self, fc):
    return self.ppm / 1.0e6 * 2 * pi * fc / self.sample_rate

  def set_rx_freq(self, fc):
    if self.phy_freq_offset != 0:
      fc += self.phy_freq_offset
      print("[#] Shifting RX freq. to %s (offset is %s)"
        % (eng_notation.num_to_str(fc),
          eng_notation.num_to_str(self.freq_offset)))
    self.phy_src.set_center_freq(fc, 0)
    self.rotator_src.set_phase_inc(self.calc_phase_inc(fc))
    self.rx_freq = fc

  def set_tx_freq(self, fc):
    if self.phy_freq_offset != 0:
      fc += self.phy_freq_offset
      print("[#] Shifting TX freq. to %s (offset is %s)"
        % (eng_notation.num_to_str(fc),
          eng_notation.num_to_str(self.freq_offset)))
    self.phy_sink.set_center_freq(fc, 0)
    self.rotator_sink.set_phase_inc(-self.calc_phase_inc(fc))
    self.tx_freq = fc

  def set_rx_gain(self, gain):
    self.phy_src.set_gain(gain, 0)
    self.rx_gain = gain

  def set_tx_gain(self, gain):
    self.phy_sink.set_gain(gain, 0)
    self.tx_gain = gain

  def set_ta(self, ta):
    print("[i] Setting TA value %d" % ta)
    advance_time_sec = ta * self.GSM_SYM_PERIOD_uS * 1e-6
    self.tx_time_setter.set_timing_advance(advance_time_sec)