Implement transceiver interface
This change introduces a new block 'TRX Interface', which is aimed
to provide an interface for external applications, such as Osmocom
MS side stack implementation - OsmocomBB. Currently one allows to
exchange raw GSM bursts between GR-GSM and other applications.
Moreover, there is a new 'trx.py' application, which implements a
simple follow graph, where all demodulated bursts are being sent
to external application via UDP link provided by 'TRX Interface'.
OsmoTRX (Osmocom's fork of OpenBTS transceiver) like control
interface is used to initialize, configure, start and stop the
application. Messages on this interface are human readable ASCII
strings, which contain a command and some related parameters.
diff --git a/apps/trx/radio_if.py b/apps/trx/radio_if.py
new file mode 100644
index 0000000..41eb3e8
--- /dev/null
+++ b/apps/trx/radio_if.py
@@ -0,0 +1,184 @@
+#!/usr/bin/env python2
+# -*- coding: utf-8 -*-
+
+# GR-GSM based transceiver
+# Follow graph implementation
+#
+# (C) 2016-2017 by Vadim Yanitskiy <axilirator@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
+import osmosdr
+
+from math import pi
+
+from gnuradio.eng_option import eng_option
+from gnuradio import eng_notation
+from gnuradio.filter import firdes
+from gnuradio import blocks
+from gnuradio import gr
+
+class RadioInterface(gr.top_block):
+ # PHY specific variables
+ samp_rate = 2000000
+ shiftoff = 400e3
+ subdev_spec = "" # TODO: use it
+ device_args = ""
+ fc = 941.6e6 # TODO: set ARFCN to 0?
+ gain = 30
+ ppm = 0
+
+ # Application state flags
+ trx_started = False
+ fc_set = False
+
+ def __init__(self, phy_args, phy_subdev_spec,
+ phy_sample_rate, phy_gain, phy_ppm,
+ trx_remote_addr, trx_base_port):
+ print("[i] Init Radio interface")
+
+ # TRX block specific variables
+ self.trx_remote_addr = trx_remote_addr
+ self.trx_base_port = trx_base_port
+
+ # PHY specific variables
+ self.subdev_spec = phy_subdev_spec
+ self.samp_rate = phy_sample_rate
+ self.device_args = phy_args
+ self.gain = phy_gain
+ self.ppm = phy_ppm
+
+ gr.top_block.__init__(self, "GR-GSM TRX")
+ shift_fc = self.fc - self.shiftoff
+
+ ##################################################
+ # PHY Definition
+ ##################################################
+ self.phy = osmosdr.source(
+ args = "numchan=%d %s" % (1, self.device_args))
+
+ self.phy.set_bandwidth(250e3 + abs(self.shiftoff), 0)
+ self.phy.set_center_freq(shift_fc, 0)
+ self.phy.set_sample_rate(self.samp_rate)
+ self.phy.set_freq_corr(self.ppm, 0)
+ self.phy.set_iq_balance_mode(2, 0)
+ self.phy.set_dc_offset_mode(2, 0)
+ self.phy.set_gain_mode(False, 0)
+ self.phy.set_gain(self.gain, 0)
+ self.phy.set_if_gain(20, 0)
+ self.phy.set_bb_gain(20, 0)
+ self.phy.set_antenna("", 0)
+
+ ##################################################
+ # GR-GSM Magic
+ ##################################################
+ self.blocks_rotator = blocks.rotator_cc(
+ -2 * pi * self.shiftoff / self.samp_rate)
+
+ self.gsm_input = grgsm.gsm_input(
+ ppm = self.ppm, osr = 4, fc = self.fc,
+ samp_rate_in = self.samp_rate)
+
+ self.gsm_receiver = grgsm.receiver(4, ([0]), ([]))
+
+ self.gsm_clck_ctrl = grgsm.clock_offset_control(
+ shift_fc, self.samp_rate, osr = 4)
+
+ # TODO: implement configurable TS filter
+ self.gsm_ts_filter = grgsm.burst_timeslot_filter(0)
+
+ self.gsm_trx_if = grgsm.trx(self.trx_remote_addr,
+ str(self.trx_base_port))
+
+ ##################################################
+ # Connections
+ ##################################################
+ self.connect((self.phy, 0), (self.blocks_rotator, 0))
+ self.connect((self.blocks_rotator, 0), (self.gsm_input, 0))
+ self.connect((self.gsm_input, 0), (self.gsm_receiver, 0))
+
+ self.msg_connect((self.gsm_receiver, 'measurements'),
+ (self.gsm_clck_ctrl, 'measurements'))
+
+ self.msg_connect((self.gsm_clck_ctrl, 'ctrl'),
+ (self.gsm_input, 'ctrl_in'))
+
+ self.msg_connect((self.gsm_receiver, 'C0'),
+ (self.gsm_ts_filter, 'in'))
+
+ self.msg_connect((self.gsm_ts_filter, 'out'),
+ (self.gsm_trx_if, 'bursts'))
+
+ def check_available(self):
+ return self.fc_set
+
+ def shutdown(self):
+ print("[i] Shutdown Radio interface")
+ self.stop()
+ self.wait()
+
+ def get_args(self):
+ return self.args
+
+ def set_args(self, args):
+ self.args = args
+
+ def get_fc(self):
+ return self.fc
+
+ def set_fc(self, fc):
+ self.phy.set_center_freq(fc - self.shiftoff, 0)
+ self.gsm_input.set_fc(fc)
+ self.fc_set = True
+ self.fc = fc
+
+ def get_gain(self):
+ return self.gain
+
+ def set_gain(self, gain):
+ self.phy.set_gain(gain, 0)
+ self.gain = gain
+
+ def get_ppm(self):
+ return self.ppm
+
+ def set_ppm(self, ppm):
+ self.rtlsdr_source_0.set_freq_corr(ppm, 0)
+ self.ppm = ppm
+
+ def get_samp_rate(self):
+ return self.samp_rate
+
+ def set_samp_rate(self, samp_rate):
+ self.blocks_rotator.set_phase_inc(
+ -2 * pi * self.shiftoff / samp_rate)
+ self.gsm_input.set_samp_rate_in(samp_rate)
+ self.phy.set_sample_rate(samp_rate)
+ self.samp_rate = samp_rate
+
+ def get_shiftoff(self):
+ return self.shiftoff
+
+ def set_shiftoff(self, shiftoff):
+ self.blocks_rotator.set_phase_inc(
+ -2 * pi * shiftoff / self.samp_rate)
+ self.phy.set_bandwidth(250e3 + abs(shiftoff), 0)
+ self.phy.set_center_freq(self.fc - shiftoff, 0)
+ self.shiftoff = shiftoff