Added new blocks written in python for new experimental gsm receiver.
FCCH burst tagger is element of hierarchical block - FCCH detector that adds tags after every detected FCCH burst. The value of each tag is a frequency offset estimate.
SCH detector waits for tags from FCCH detector which are used to find SCH burst position. It is unfinished.
diff --git a/examples/gsm_fcch_detector.grc b/examples/gsm_fcch_detector.grc
new file mode 100644
index 0000000..1d69b53
--- /dev/null
+++ b/examples/gsm_fcch_detector.grc
@@ -0,0 +1,567 @@
+<?xml version='1.0' encoding='ASCII'?>
+<flow_graph>
+ <timestamp>Tue Jul 8 19:32:53 2014</timestamp>
+ <block>
+ <key>variable</key>
+ <param>
+ <key>id</key>
+ <value>samp_rate</value>
+ </param>
+ <param>
+ <key>_enabled</key>
+ <value>True</value>
+ </param>
+ <param>
+ <key>value</key>
+ <value>f_symb*OSR</value>
+ </param>
+ <param>
+ <key>_coordinate</key>
+ <value>(10, 170)</value>
+ </param>
+ <param>
+ <key>_rotation</key>
+ <value>0</value>
+ </param>
+ </block>
+ <block>
+ <key>variable</key>
+ <param>
+ <key>id</key>
+ <value>f_symb</value>
+ </param>
+ <param>
+ <key>_enabled</key>
+ <value>True</value>
+ </param>
+ <param>
+ <key>value</key>
+ <value>1625000.0/6.0</value>
+ </param>
+ <param>
+ <key>_coordinate</key>
+ <value>(11, 239)</value>
+ </param>
+ <param>
+ <key>_rotation</key>
+ <value>0</value>
+ </param>
+ </block>
+ <block>
+ <key>parameter</key>
+ <param>
+ <key>id</key>
+ <value>OSR</value>
+ </param>
+ <param>
+ <key>_enabled</key>
+ <value>True</value>
+ </param>
+ <param>
+ <key>label</key>
+ <value>OverSamplingRatio</value>
+ </param>
+ <param>
+ <key>value</key>
+ <value>4</value>
+ </param>
+ <param>
+ <key>type</key>
+ <value>intx</value>
+ </param>
+ <param>
+ <key>short_id</key>
+ <value></value>
+ </param>
+ <param>
+ <key>_coordinate</key>
+ <value>(264, 4)</value>
+ </param>
+ <param>
+ <key>_rotation</key>
+ <value>0</value>
+ </param>
+ </block>
+ <block>
+ <key>blocks_complex_to_arg</key>
+ <param>
+ <key>id</key>
+ <value>blocks_complex_to_arg_0</value>
+ </param>
+ <param>
+ <key>_enabled</key>
+ <value>True</value>
+ </param>
+ <param>
+ <key>vlen</key>
+ <value>1</value>
+ </param>
+ <param>
+ <key>affinity</key>
+ <value></value>
+ </param>
+ <param>
+ <key>minoutbuf</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>maxoutbuf</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>_coordinate</key>
+ <value>(641, 158)</value>
+ </param>
+ <param>
+ <key>_rotation</key>
+ <value>0</value>
+ </param>
+ </block>
+ <block>
+ <key>blocks_multiply_conjugate_cc</key>
+ <param>
+ <key>id</key>
+ <value>blocks_multiply_conjugate_cc_0</value>
+ </param>
+ <param>
+ <key>_enabled</key>
+ <value>True</value>
+ </param>
+ <param>
+ <key>vlen</key>
+ <value>1</value>
+ </param>
+ <param>
+ <key>affinity</key>
+ <value></value>
+ </param>
+ <param>
+ <key>minoutbuf</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>maxoutbuf</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>_coordinate</key>
+ <value>(444, 141)</value>
+ </param>
+ <param>
+ <key>_rotation</key>
+ <value>0</value>
+ </param>
+ </block>
+ <block>
+ <key>blocks_delay</key>
+ <param>
+ <key>id</key>
+ <value>blocks_delay_0</value>
+ </param>
+ <param>
+ <key>_enabled</key>
+ <value>True</value>
+ </param>
+ <param>
+ <key>type</key>
+ <value>complex</value>
+ </param>
+ <param>
+ <key>delay</key>
+ <value>int(OSR)</value>
+ </param>
+ <param>
+ <key>num_ports</key>
+ <value>1</value>
+ </param>
+ <param>
+ <key>vlen</key>
+ <value>1</value>
+ </param>
+ <param>
+ <key>affinity</key>
+ <value></value>
+ </param>
+ <param>
+ <key>minoutbuf</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>maxoutbuf</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>_coordinate</key>
+ <value>(319, 171)</value>
+ </param>
+ <param>
+ <key>_rotation</key>
+ <value>0</value>
+ </param>
+ </block>
+ <block>
+ <key>blocks_moving_average_xx</key>
+ <param>
+ <key>id</key>
+ <value>blocks_moving_average_xx_0</value>
+ </param>
+ <param>
+ <key>_enabled</key>
+ <value>True</value>
+ </param>
+ <param>
+ <key>type</key>
+ <value>float</value>
+ </param>
+ <param>
+ <key>length</key>
+ <value>int((142)*samp_rate/f_symb)</value>
+ </param>
+ <param>
+ <key>scale</key>
+ <value>1</value>
+ </param>
+ <param>
+ <key>max_iter</key>
+ <value>int(1e6)</value>
+ </param>
+ <param>
+ <key>affinity</key>
+ <value></value>
+ </param>
+ <param>
+ <key>minoutbuf</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>maxoutbuf</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>_coordinate</key>
+ <value>(971, 138)</value>
+ </param>
+ <param>
+ <key>_rotation</key>
+ <value>0</value>
+ </param>
+ </block>
+ <block>
+ <key>blocks_threshold_ff</key>
+ <param>
+ <key>id</key>
+ <value>blocks_threshold_ff_0_0</value>
+ </param>
+ <param>
+ <key>_enabled</key>
+ <value>True</value>
+ </param>
+ <param>
+ <key>low</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>high</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>init</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>affinity</key>
+ <value></value>
+ </param>
+ <param>
+ <key>minoutbuf</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>maxoutbuf</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>_coordinate</key>
+ <value>(815, 138)</value>
+ </param>
+ <param>
+ <key>_rotation</key>
+ <value>0</value>
+ </param>
+ </block>
+ <block>
+ <key>pad_source</key>
+ <param>
+ <key>id</key>
+ <value>pad_source_0</value>
+ </param>
+ <param>
+ <key>_enabled</key>
+ <value>True</value>
+ </param>
+ <param>
+ <key>label</key>
+ <value>in</value>
+ </param>
+ <param>
+ <key>type</key>
+ <value>complex</value>
+ </param>
+ <param>
+ <key>vlen</key>
+ <value>1</value>
+ </param>
+ <param>
+ <key>num_streams</key>
+ <value>1</value>
+ </param>
+ <param>
+ <key>optional</key>
+ <value>False</value>
+ </param>
+ <param>
+ <key>_coordinate</key>
+ <value>(155, 137)</value>
+ </param>
+ <param>
+ <key>_rotation</key>
+ <value>0</value>
+ </param>
+ </block>
+ <block>
+ <key>blocks_threshold_ff</key>
+ <param>
+ <key>id</key>
+ <value>blocks_threshold_ff_0</value>
+ </param>
+ <param>
+ <key>_enabled</key>
+ <value>True</value>
+ </param>
+ <param>
+ <key>low</key>
+ <value>int((138)*samp_rate/f_symb)</value>
+ </param>
+ <param>
+ <key>high</key>
+ <value>int((138)*samp_rate/f_symb)</value>
+ </param>
+ <param>
+ <key>init</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>affinity</key>
+ <value></value>
+ </param>
+ <param>
+ <key>minoutbuf</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>maxoutbuf</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>_coordinate</key>
+ <value>(1150, 138)</value>
+ </param>
+ <param>
+ <key>_rotation</key>
+ <value>0</value>
+ </param>
+ </block>
+ <block>
+ <key>gsm_fcch_burst_tagger</key>
+ <param>
+ <key>id</key>
+ <value>gsm_fcch_burst_tagger_0</value>
+ </param>
+ <param>
+ <key>_enabled</key>
+ <value>True</value>
+ </param>
+ <param>
+ <key>OSR</key>
+ <value>OSR</value>
+ </param>
+ <param>
+ <key>affinity</key>
+ <value></value>
+ </param>
+ <param>
+ <key>minoutbuf</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>maxoutbuf</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>_coordinate</key>
+ <value>(348, 303)</value>
+ </param>
+ <param>
+ <key>_rotation</key>
+ <value>0</value>
+ </param>
+ </block>
+ <block>
+ <key>pad_sink</key>
+ <param>
+ <key>id</key>
+ <value>pad_sink_0</value>
+ </param>
+ <param>
+ <key>_enabled</key>
+ <value>True</value>
+ </param>
+ <param>
+ <key>label</key>
+ <value>out</value>
+ </param>
+ <param>
+ <key>type</key>
+ <value>complex</value>
+ </param>
+ <param>
+ <key>vlen</key>
+ <value>1</value>
+ </param>
+ <param>
+ <key>num_streams</key>
+ <value>1</value>
+ </param>
+ <param>
+ <key>optional</key>
+ <value>False</value>
+ </param>
+ <param>
+ <key>_coordinate</key>
+ <value>(584, 316)</value>
+ </param>
+ <param>
+ <key>_rotation</key>
+ <value>0</value>
+ </param>
+ </block>
+ <block>
+ <key>options</key>
+ <param>
+ <key>id</key>
+ <value>fcch_detector</value>
+ </param>
+ <param>
+ <key>_enabled</key>
+ <value>True</value>
+ </param>
+ <param>
+ <key>title</key>
+ <value>FCCH Bursts Detector</value>
+ </param>
+ <param>
+ <key>author</key>
+ <value>Piotr Krysik</value>
+ </param>
+ <param>
+ <key>description</key>
+ <value>Detects positions of FCCH bursts. At the end of each detected FCCH burst adds to the stream a tag with key "fcch" and value which is a frequency offset estimate. The input sampling frequency should be integer multiply of GSM GMKS symbol rate - 1625000/6 Hz.</value>
+ </param>
+ <param>
+ <key>window_size</key>
+ <value>1280, 1024</value>
+ </param>
+ <param>
+ <key>generate_options</key>
+ <value>hb</value>
+ </param>
+ <param>
+ <key>category</key>
+ <value>GSM</value>
+ </param>
+ <param>
+ <key>run_options</key>
+ <value>prompt</value>
+ </param>
+ <param>
+ <key>run</key>
+ <value>True</value>
+ </param>
+ <param>
+ <key>max_nouts</key>
+ <value>0</value>
+ </param>
+ <param>
+ <key>realtime_scheduling</key>
+ <value></value>
+ </param>
+ <param>
+ <key>_coordinate</key>
+ <value>(8, 0)</value>
+ </param>
+ <param>
+ <key>_rotation</key>
+ <value>0</value>
+ </param>
+ </block>
+ <connection>
+ <source_block_id>pad_source_0</source_block_id>
+ <sink_block_id>blocks_multiply_conjugate_cc_0</sink_block_id>
+ <source_key>0</source_key>
+ <sink_key>0</sink_key>
+ </connection>
+ <connection>
+ <source_block_id>blocks_delay_0</source_block_id>
+ <sink_block_id>blocks_multiply_conjugate_cc_0</sink_block_id>
+ <source_key>0</source_key>
+ <sink_key>1</sink_key>
+ </connection>
+ <connection>
+ <source_block_id>blocks_complex_to_arg_0</source_block_id>
+ <sink_block_id>blocks_threshold_ff_0_0</sink_block_id>
+ <source_key>0</source_key>
+ <sink_key>0</sink_key>
+ </connection>
+ <connection>
+ <source_block_id>pad_source_0</source_block_id>
+ <sink_block_id>blocks_delay_0</sink_block_id>
+ <source_key>0</source_key>
+ <sink_key>0</sink_key>
+ </connection>
+ <connection>
+ <source_block_id>blocks_multiply_conjugate_cc_0</source_block_id>
+ <sink_block_id>blocks_complex_to_arg_0</sink_block_id>
+ <source_key>0</source_key>
+ <sink_key>0</sink_key>
+ </connection>
+ <connection>
+ <source_block_id>blocks_moving_average_xx_0</source_block_id>
+ <sink_block_id>blocks_threshold_ff_0</sink_block_id>
+ <source_key>0</source_key>
+ <sink_key>0</sink_key>
+ </connection>
+ <connection>
+ <source_block_id>blocks_threshold_ff_0_0</source_block_id>
+ <sink_block_id>blocks_moving_average_xx_0</sink_block_id>
+ <source_key>0</source_key>
+ <sink_key>0</sink_key>
+ </connection>
+ <connection>
+ <source_block_id>gsm_fcch_burst_tagger_0</source_block_id>
+ <sink_block_id>pad_sink_0</sink_block_id>
+ <source_key>0</source_key>
+ <sink_key>0</sink_key>
+ </connection>
+ <connection>
+ <source_block_id>pad_source_0</source_block_id>
+ <sink_block_id>gsm_fcch_burst_tagger_0</sink_block_id>
+ <source_key>0</source_key>
+ <sink_key>0</sink_key>
+ </connection>
+ <connection>
+ <source_block_id>blocks_threshold_ff_0</source_block_id>
+ <sink_block_id>gsm_fcch_burst_tagger_0</sink_block_id>
+ <source_key>0</source_key>
+ <sink_key>1</sink_key>
+ </connection>
+</flow_graph>
diff --git a/grc/CMakeLists.txt b/grc/CMakeLists.txt
index 2c73b8d..6de687a 100644
--- a/grc/CMakeLists.txt
+++ b/grc/CMakeLists.txt
@@ -18,5 +18,8 @@
# Boston, MA 02110-1301, USA.
install(FILES
gsm_receiver_hier.xml
- gsm_bursts_printer.xml DESTINATION share/gnuradio/grc/blocks
+ gsm_bursts_printer.xml
+ gsm_fcch_burst_tagger.xml
+ gsm_sch_detector.xml
+ gsm_fcch_detector.xml DESTINATION share/gnuradio/grc/blocks
)
diff --git a/grc/gsm_fcch_burst_tagger.xml b/grc/gsm_fcch_burst_tagger.xml
new file mode 100644
index 0000000..90f5688
--- /dev/null
+++ b/grc/gsm_fcch_burst_tagger.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0"?>
+<block>
+ <name>fcch_burst_tagger</name>
+ <key>gsm_fcch_burst_tagger</key>
+ <category>GSM</category>
+ <import>import gsm</import>
+ <make>gsm.fcch_burst_tagger($OSR)</make>
+ <param>
+ <name>OSR</name>
+ <key>OSR</key>
+ <type>int</type>
+ </param>
+
+ <sink>
+ <name>in</name>
+ <type>complex</type>
+ </sink>
+
+ <sink>
+ <name>threshold</name>
+ <type>float</type>
+ </sink>
+
+ <source>
+ <name>out</name>
+ <type>complex</type>
+ </source>
+</block>
diff --git a/grc/gsm_fcch_detector.xml b/grc/gsm_fcch_detector.xml
new file mode 100644
index 0000000..32d5379
--- /dev/null
+++ b/grc/gsm_fcch_detector.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0"?>
+<block>
+ <name>fcch_detector</name>
+ <key>gsm_fcch_detector</key>
+ <category>GSM</category>
+ <import>import gsm</import>
+ <make>gsm.fcch_detector($OSR)</make>
+<callback>set_OSR($OSR)</callback>
+ <param>
+ <name>OverSamplingRatio</name>
+ <key>OSR</key>
+ <value>4</value>
+ <type>raw</type>
+ </param>
+ <sink>
+ <name>in</name>
+ <type>complex</type>
+ <vlen>1</vlen>
+ </sink>
+ <source>
+ <name>out</name>
+ <type>complex</type>
+ <vlen>1</vlen>
+ </source>
+ <doc>Piotr Krysik
+Detects positions of FCCH bursts. At the end of each detected FCCH burst adds to the stream a tag with key "fcch" and value which is a frequency offset estimate. The input sampling frequency should be integer multiply of GSM GMKS symbol rate - 1625000/6 Hz.</doc>
+ <grc_source>/home/piotr/Odbiornik_gsm/gr-gsm/examples/gsm_fcch_detector.grc</grc_source>
+</block>
diff --git a/grc/gsm_sch_detector.xml b/grc/gsm_sch_detector.xml
new file mode 100644
index 0000000..7832f4a
--- /dev/null
+++ b/grc/gsm_sch_detector.xml
@@ -0,0 +1,24 @@
+<?xml version="1.0"?>
+<block>
+ <name>sch_detector</name>
+ <key>gsm_sch_detector</key>
+ <category>GSM</category>
+ <import>import gsm</import>
+ <make>gsm.sch_detector($OSR)</make>
+ <param>
+ <name>OSR</name>
+ <key>OSR</key>
+ <type>int</type>
+<!-- <value>OSR</value>-->
+ </param>
+
+ <sink>
+ <name>in</name>
+ <type>complex</type>
+ </sink>
+
+ <source>
+ <name>out</name>
+ <type>complex</type>
+ </source>
+</block>
diff --git a/python/CMakeLists.txt b/python/CMakeLists.txt
index 8640d73..2c76806 100644
--- a/python/CMakeLists.txt
+++ b/python/CMakeLists.txt
@@ -31,7 +31,10 @@
GR_PYTHON_INSTALL(
FILES
__init__.py
- receiver_hier.py DESTINATION ${GR_PYTHON_DIR}/gsm
+ receiver_hier.py
+ fcch_burst_tagger.py
+ sch_detector.py
+ fcch_detector.py DESTINATION ${GR_PYTHON_DIR}/gsm
)
########################################################################
diff --git a/python/__init__.py b/python/__init__.py
index d6dec38..ee72a0b 100644
--- a/python/__init__.py
+++ b/python/__init__.py
@@ -46,6 +46,10 @@
# import any pure python here
from receiver_hier import receiver_hier
+
+from fcch_burst_tagger import fcch_burst_tagger
+from sch_detector import sch_detector
+from fcch_detector import fcch_detector
#
# ----------------------------------------------------------------
diff --git a/python/fcch_burst_tagger.py b/python/fcch_burst_tagger.py
new file mode 100644
index 0000000..5142096
--- /dev/null
+++ b/python/fcch_burst_tagger.py
@@ -0,0 +1,125 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+#
+# Copyright 2014 Piotr Krysik pkrysik@elka.pw.edu.pl
+#
+# 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.
+#
+
+from numpy import *
+from pylab import *
+from gnuradio import gr
+import pmt
+from scipy.signal.chirpz import ZoomFFT
+
+class fcch_burst_tagger(gr.sync_block):
+ """
+ docstring for block fcch_burst_tagger
+ """
+ def __init__(self, OSR):
+ gr.sync_block.__init__(self,
+ name="fcch_burst_tagger",
+ in_sig=[complex64, float32],
+ out_sig=[complex64])
+
+ self.state=False
+ self.symbol_rate = 1625000/6
+ self.OSR=OSR
+ self.samp_rate = self.symbol_rate*OSR
+ self.burst_size = int(156.25*self.OSR)
+ self.guard_period = int(round(8.25*self.OSR))
+ self.block_size = self.burst_size+self.guard_period
+ self.processed_block_size = int(142*self.OSR)
+ self.set_history(self.burst_size)
+ self.set_output_multiple(self.guard_period)
+ self.prev_offset=0
+
+ #parameters of zoomfft frequency estimator
+ f1 = self.symbol_rate/4*0.9
+ f2 = self.symbol_rate/4*1.1
+ m=5000*self.OSR
+ self.zoomfft = ZoomFFT(self.processed_block_size, f1, f2, m, Fs=self.samp_rate)
+ self.f_axis = linspace(f1,f2,m)
+
+ def work(self, input_items, output_items):
+ in0=input_items[0]
+ output_items[0][:] = in0[self.history()-1:]
+
+ threshold = input_items[1][self.history()-1:]
+ threshold_diff = diff(concatenate([[0],threshold]))
+ up_to_high_indexes = nonzero(threshold_diff>0)[0]
+
+ up_to_high_idx=[]
+
+ for up_to_high_idx in up_to_high_indexes: #look for "high" value at the trigger
+ if up_to_high_idx==0 and self.state==True: #if it's not transition from "low" to "high"
+ continue #then continue
+ self.state=True #if found - change state
+
+ if self.state==True and up_to_high_idx and any(threshold_diff<0): #and look for transition from high to low
+ last_up_to_high_idx = up_to_high_idx
+ last_high_to_low_idx = nonzero(threshold_diff<0)[0][-1]
+
+ if last_high_to_low_idx-last_up_to_high_idx>0:
+ coarse_idx = int(last_high_to_low_idx+self.history()-self.guard_period-self.burst_size)
+ inst_freq = angle(in0[coarse_idx:coarse_idx+self.block_size]*in0[coarse_idx-self.OSR:coarse_idx+self.block_size-self.OSR].conj())/(2*pi)*self.symbol_rate #instantaneus frequency estimate
+ precise_idx = self.find_best_position(inst_freq)
+# measured_freq = mean(inst_freq[precise_idx:precise_idx+self.processed_block_size])
+ expected_freq = self.symbol_rate/4
+ zoomed_spectrum = abs(self.zoomfft(in0[coarse_idx+precise_idx:coarse_idx+precise_idx+self.processed_block_size]))
+ measured_freq = self.f_axis[argmax(zoomed_spectrum)]
+ freq_offset = measured_freq - expected_freq
+ offset = self.nitems_written(0) + coarse_idx + precise_idx - self.guard_period
+ key = pmt.string_to_symbol("fcch")
+ value = pmt.from_double(freq_offset)
+ self.add_item_tag(0,offset, key, value)
+ self.state=False
+
+# Some additional plots and prints for debugging
+# print "coarse_idx+precise_idx",coarse_idx+precise_idx
+# print "offset-self.nitems_written(0):",offset-self.nitems_written(0)
+ print offset-self.prev_offset
+ self.prev_offset=offset
+ print "freq offset", freq_offset
+# freq_offset = measured_freq - expected_freq
+# plot(self.f_axis, zoomed_spectrum)
+# show()
+# plot(inst_freq[precise_idx:precise_idx+self.burst_size])
+# show()
+# plot(unwrap(angle(in0[coarse_idx+precise_idx:coarse_idx+precise_idx+self.burst_size])))
+# show()
+#
+ return len(output_items[0])
+
+ def find_best_position(self, inst_freq):
+ lowest_max_min_diff = 1e6 #1e6 - just some large value
+ start_pos = 0
+
+ for ii in xrange(0,int(30*self.OSR)):
+ min_inst_freq = min(inst_freq[ii:self.processed_block_size+ii-1]);
+ max_inst_freq = max(inst_freq[ii:self.processed_block_size+ii-1]);
+
+ if (lowest_max_min_diff > max_inst_freq - min_inst_freq):
+ lowest_max_min_diff = max_inst_freq - min_inst_freq;
+ start_pos = ii
+# print 'start_pos',start_pos
+
+# plot(xrange(start_pos,start_pos+self.processed_block_size),inst_freq[start_pos:start_pos+self.processed_block_size],'r.')
+# hold(True)
+# plot(inst_freq)
+# show()
+
+ return start_pos
diff --git a/python/fcch_detector.py b/python/fcch_detector.py
new file mode 100644
index 0000000..627dd00
--- /dev/null
+++ b/python/fcch_detector.py
@@ -0,0 +1,71 @@
+#!/usr/bin/env python
+##################################################
+# Gnuradio Python Flow Graph
+# Title: FCCH Bursts Detector
+# Author: Piotr Krysik
+#
+# Description: Detects positions of FCCH bursts. At the end of each
+# detected FCCH burst adds to the stream a tag with key "fcch" and value
+# which is a frequency offset estimate. The input sampling frequency
+# should be integer multiply of GSM GMKS symbol rate - 1625000/6 Hz.
+##################################################
+
+from gnuradio import blocks
+from gnuradio import gr
+from gnuradio.filter import firdes
+import gsm
+
+class fcch_detector(gr.hier_block2):
+
+ def __init__(self, OSR=4):
+ gr.hier_block2.__init__(
+ self, "FCCH bursts detector",
+ gr.io_signature(1, 1, gr.sizeof_gr_complex*1),
+ gr.io_signature(1, 1, gr.sizeof_gr_complex*1),
+ )
+
+ ##################################################
+ # Parameters
+ ##################################################
+ self.OSR = OSR
+
+ ##################################################
+ # Variables
+ ##################################################
+ self.f_symb = f_symb = 1625000.0/6.0
+ self.samp_rate = samp_rate = f_symb*OSR
+
+ ##################################################
+ # Blocks
+ ##################################################
+ self.gsm_fcch_burst_tagger_0 = gsm.fcch_burst_tagger(OSR)
+ self.blocks_threshold_ff_0_0 = blocks.threshold_ff(0, 0, 0)
+ self.blocks_threshold_ff_0 = blocks.threshold_ff(int((138)*samp_rate/f_symb), int((138)*samp_rate/f_symb), 0)
+ self.blocks_multiply_conjugate_cc_0 = blocks.multiply_conjugate_cc(1)
+ self.blocks_moving_average_xx_0 = blocks.moving_average_ff(int((142)*samp_rate/f_symb), 1, int(1e6))
+ self.blocks_delay_0 = blocks.delay(gr.sizeof_gr_complex*1, int(OSR))
+ self.blocks_complex_to_arg_0 = blocks.complex_to_arg(1)
+
+ ##################################################
+ # Connections
+ ##################################################
+ self.connect((self, 0), (self.blocks_multiply_conjugate_cc_0, 0))
+ self.connect((self.blocks_delay_0, 0), (self.blocks_multiply_conjugate_cc_0, 1))
+ self.connect((self.blocks_complex_to_arg_0, 0), (self.blocks_threshold_ff_0_0, 0))
+ self.connect((self, 0), (self.blocks_delay_0, 0))
+ self.connect((self.blocks_multiply_conjugate_cc_0, 0), (self.blocks_complex_to_arg_0, 0))
+ self.connect((self.blocks_moving_average_xx_0, 0), (self.blocks_threshold_ff_0, 0))
+ self.connect((self.blocks_threshold_ff_0_0, 0), (self.blocks_moving_average_xx_0, 0))
+ self.connect((self.gsm_fcch_burst_tagger_0, 0), (self, 0))
+ self.connect((self, 0), (self.gsm_fcch_burst_tagger_0, 0))
+ self.connect((self.blocks_threshold_ff_0, 0), (self.gsm_fcch_burst_tagger_0, 1))
+
+ def get_OSR(self):
+ return self.OSR
+
+ def set_OSR(self, OSR):
+ self.OSR = OSR
+ self.set_samp_rate(self.f_symb*self.OSR)
+ self.blocks_delay_0.set_dly(int(self.OSR))
+
+
diff --git a/python/sch_detector.py b/python/sch_detector.py
new file mode 100644
index 0000000..d80d032
--- /dev/null
+++ b/python/sch_detector.py
@@ -0,0 +1,132 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+#
+# Copyright 2014 <+YOU OR YOUR COMPANY+>.
+#
+# 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.
+#
+
+from numpy import *
+from pylab import *
+from gnuradio import gr
+import pmt
+from scipy.ndimage.filters import uniform_filter1d
+
+class sch_receiver():
+ """
+ docstring for class sch_reciever
+ """
+ def __init__(self, OSR):
+ self.sync_seq = array([1, 0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0,
+ 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1,
+ 0, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1,
+ 0, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 1, 1])
+ self.OSR = OSR
+ sync_seq_msk_tmp = self.msk_mod(self.sync_seq, -1j)
+ self.sync_seq_msk = sync_seq_msk_tmp[5:59]
+ self.sync_seq_msk_interp = zeros(self.OSR*len(self.sync_seq_msk), dtype=np.complex64)
+ self.sync_seq_msk_interp[::OSR] = self.sync_seq_msk
+ self.L = 5
+
+ def msk_mod(self, x, start_point):
+ x_nrz = 2*x-1
+ x_diffenc = x_nrz[1:]*x_nrz[0:-1]
+ mod_tmp = concatenate((array([start_point]),1j*x_diffenc))
+ return cumprod(mod_tmp)
+
+ def get_chan_imp_resp(self, sch_burst):
+ sch_burst_bl = resize(array(sch_burst), (int(len(sch_burst)/self.OSR),self.OSR))
+ correlation_bl = zeros(shape(sch_burst_bl), dtype=np.complex64)
+ for ii in xrange(0,self.OSR):
+ correlation_bl[:,ii]=correlate(sch_burst_bl[:,ii],self.sync_seq_msk,'same')
+
+ correlation_bl = correlation_bl/len(self.sync_seq_msk)
+ power_bl_mov_avg = uniform_filter1d(abs(correlation_bl)**2,5,mode='constant',axis=0)
+
+ print "correlation_bl.argmax()",argmax(abs(hstack(correlation_bl)))
+ print "power_bl_mov_avg.argmax()",hstack(power_bl_mov_avg).argmax()
+ print 'unravel_index(correlation_bl.argmax(), correlation_bl.shape)',unravel_index(correlation_bl.argmax(), correlation_bl.shape)
+ print 'unravel_index(power_bl_mov_avg.argmax(), power_bl_mov_avg.shape)',unravel_index(power_bl_mov_avg.argmax(), power_bl_mov_avg.shape)
+# correlation = zeros(shape(sch_burst))
+# correlation = correlate(sch_burst, self.sync_seq_msk_interp,'same')/len(self.sync_seq_msk)
+# print "pozycja maksimum",argmax(abs(correlation))
+ plot(abs(hstack(correlation_bl))*1000)
+# hold(True)
+# plot(abs(sch_burst)*500)
+# print shape(range(0,len(sch_burst),self.OSR))
+# print shape(correlation_bl[:,0])
+ for ii in range(0,self.OSR):
+ plot(range(ii,len(correlation_bl[:,0])*self.OSR,self.OSR),power_bl_mov_avg[:,ii]*5e6,'r.')
+ show()
+ def receive(self, input_corr, chan_imp_resp):
+ pass
+
+class sch_detector(gr.sync_block):
+ """
+ docstring for block sch_detector
+ """
+ def __init__(self, OSR):
+ gr.sync_block.__init__(self,
+ name="sch_detector",
+ in_sig=[complex64],
+ out_sig=[complex64])
+ self.OSR = OSR
+ self.states = {"waiting_for_fcch_tag":1, "reaching_sch_burst":2, "sch_at_input_buffer":3}
+ self.state = self.states["waiting_for_fcch_tag"]
+ self.sch_offset = -100 #-100 - just some invalid value of sch burst position in the stream
+ self.burst_size = int(round(156.25*self.OSR))
+ self.guard_period = int(round(8.25*self.OSR))
+ self.block_size = self.burst_size + self.guard_period
+ self.set_history(self.block_size)
+ self.set_output_multiple(self.guard_period)
+ self.sch_receiver = sch_receiver(OSR)
+
+ def work(self, input_items, output_items):
+ in0 = input_items[0]
+ out = output_items[0]
+ to_consume = len(in0)-self.history()
+
+ if self.state == self.states["waiting_for_fcch_tag"]:
+ fcch_tags = []
+
+ start = self.nitems_written(0)
+ stop = start + len(in0)
+ key = pmt.string_to_symbol("fcch")
+ fcch_tags = self.get_tags_in_range(0, start, stop, key)
+ if fcch_tags:
+ self.sch_offset = fcch_tags[0].offset + int(round(8*self.burst_size+0*self.guard_period)) #156.25 is number of GMSK symbols per timeslot,
+ #8.25 is arbitrary safety margin in order to avoid cutting boundary of SCH burst
+ self.state = self.states["reaching_sch_burst"]
+
+ elif self.state == self.states["reaching_sch_burst"]:
+ samples_left = self.sch_offset-self.nitems_written(0)
+ if samples_left <= len(in0)-self.history():
+ to_consume = samples_left
+ self.state = self.states["sch_at_input_buffer"]
+
+ elif self.state == self.states["sch_at_input_buffer"]:
+ offset = self.nitems_written(0)
+ key = pmt.string_to_symbol("sch")
+ value = pmt.from_double(0)
+ self.add_item_tag(0,offset, key, value)
+ self.state = self.states["waiting_for_fcch_tag"]
+ self.sch_receiver.get_chan_imp_resp(in0[0:self.block_size+self.guard_period])
+# plot(unwrap(angle(in0[0:2*self.block_size])))
+# show()
+
+ out[:] = in0[self.history()-1:]
+ return to_consume
+