Add TCH/H decoder block with AMR multirate support

Add new TCHH channel mode
Add two new optional arguments

    -m CHAN_MODE, --mode=CHAN_MODE
                        Channel mode. Valid options are 'BCCH' (Non-combined
                        C0), 'BCCH_SDCCH4'(Combined C0), 'SDCCH8' (Stand-alone
                        control channel) 'TCHF' (Traffic Channel, Full rate),
                        'TCHH' (Traffic Channel, Half rate)

    --sub-channel=TCH_H_CHANNEL
                        TCH/H sub-channel. [default=0]
    --multi-rate=MULTI_RATE
                        The MultiRrate configuration element from the
                        Assigment Command message. Example: 28111a40. See 3GPP
                        TS 44.018 - 10.5.2.21aa MultiRate configuration

Example:
    grgsm_decode -m TCHH --sub-channel 0 --multi-rate 2811 -o voice.amr ...

12 files changed, 621 insertions, 8 deletions

diff --git a/apps/grgsm_decode b/apps/grgsm_decode
index 9c01e66..3bc0db3 100755
--- a/apps/grgsm_decode
+++ b/apps/grgsm_decode
@@ -40,6 +40,8 @@ class grgsm_decoder(gr.top_block):
                  a5=1, a5_kc=None,
                  speech_file=None, speech_codec=None,
                  enable_voice_boundary_detection=False,
+                 tch_h_channel=0,
+                 multi_rate=0,
                  verbose=False,
                  print_bursts=False, ppm=0):
 
@@ -100,11 +102,16 @@ class grgsm_decoder(gr.top_block):
             self.tch_f_decoder = grgsm.tch_f_decoder(speech_codec, enable_voice_boundary_detection)
             self.tch_f_pdu_to_tagged_stream = blocks.pdu_to_tagged_stream(blocks.byte_t, "packet_len")
             self.tch_f_file_sink = blocks.file_sink(gr.sizeof_char*1, speech_file, False)
+        elif self.chan_mode == 'TCHH':
+            self.tch_h_demapper = grgsm.tch_h_chans_demapper(self.timeslot, tch_h_channel)
+            self.tch_h_decoder = grgsm.tch_h_decoder(tch_h_channel, multi_rate, enable_voice_boundary_detection)
+            self.tch_f_pdu_to_tagged_stream = blocks.pdu_to_tagged_stream(blocks.byte_t, "packet_len")
+            self.tch_f_file_sink = blocks.file_sink(gr.sizeof_char*1, speech_file, False)
 
         if self.kc != [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]:
             self.decryption = grgsm.decryption(self.kc, self.a5)
             self.cch_decoder_decrypted = grgsm.control_channels_decoder()
-            if self.chan_mode == 'TCHF':
+            if self.chan_mode in ('TCHF', 'TCHH'):
                 self.decryption_tch_sacch = grgsm.decryption(self.kc, self.a5)
 
         self.cch_decoder = grgsm.control_channels_decoder()
@@ -209,12 +216,32 @@ class grgsm_decoder(gr.top_block):
             if self.verbose:
                 self.msg_connect(self.tch_f_decoder, "msgs", self.message_printer, "msgs")
                 self.msg_connect(self.cch_decoder, "msgs", self.message_printer, "msgs")
-            
+
+        elif self.chan_mode == 'TCHH':
+            self.msg_connect(self.timeslot_filter, "out", self.tch_h_demapper, "bursts")
+            if self.kc != [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]:
+                self.msg_connect(self.tch_h_demapper, "acch_bursts", self.decryption_tch_sacch, "bursts")
+                self.msg_connect(self.tch_h_demapper, "tch_bursts", self.decryption, "bursts")
+
+                self.msg_connect(self.decryption_tch_sacch, "bursts", self.cch_decoder, "bursts")
+                self.msg_connect(self.decryption, "bursts", self.tch_h_decoder, "bursts")
+            else:
+                self.msg_connect(self.tch_h_demapper, "acch_bursts", self.cch_decoder, "bursts")
+                self.msg_connect(self.tch_h_demapper, "tch_bursts", self.tch_h_decoder, "bursts")
+
+            self.msg_connect(self.tch_h_decoder, "msgs", self.socket_pdu, "pdus")
+            self.msg_connect(self.cch_decoder, "msgs", self.socket_pdu, "pdus")
+            self.msg_connect(self.tch_h_decoder, "voice", self.tch_f_pdu_to_tagged_stream, "pdus")
+            self.connect((self.tch_f_pdu_to_tagged_stream, 0), (self.tch_f_file_sink, 0))
+
+            if self.verbose:
+                self.msg_connect(self.tch_h_decoder, "msgs", self.message_printer, "msgs")
+                self.msg_connect(self.cch_decoder, "msgs", self.message_printer, "msgs")
 
 if __name__ == '__main__':
 
     # List of channel configurations
-    channel_modes = ['BCCH', 'BCCH_SDCCH4', 'SDCCH8', 'TCHF']
+    channel_modes = ['BCCH', 'BCCH_SDCCH4', 'SDCCH8', 'TCHF', 'TCHH']
 
     # mapping options to grgsm's enums
     tch_codecs = collections.OrderedDict([
@@ -265,7 +292,7 @@ if __name__ == '__main__':
                       type='choice', choices=channel_modes,
                       help="Channel mode. Valid options are 'BCCH' (Non-combined C0), "
                            "'BCCH_SDCCH4'(Combined C0), 'SDCCH8' (Stand-alone control channel) "
-                           "and 'TCHF' (Traffic Channel, Full rate) ")
+                           "'TCHF' (Traffic Channel, Full rate), 'TCHH' (Traffic Channel, Half rate) ")
     parser.add_option("-t", "--timeslot", dest="timeslot", type="intx", default=0,
                       help="Timeslot to decode [default=%default]")
     parser.add_option("-u", "--subslot", dest="subslot", type="intx",
@@ -313,7 +340,12 @@ if __name__ == '__main__':
                            help="TCH-F speech codec [default=%default]. "
                                 "Valid options are " + ", ".join(tch_codecs.keys()))
     tch_options.add_option("-o", "--output-tch", dest="speech_output_file", default="/tmp/speech.au.gsm",
-                           help="TCH/F speech output file [default=%default].")
+                           help="tch/f speech output file [default=%default].")
+    tch_options.add_option("--sub-channel", dest="tch_h_channel", default="0", type='intx',
+                           help="TCH/H sub-channel. [default=0]")
+    tch_options.add_option("--multi-rate", dest="multi_rate", default="", type='string',
+                           help="The MultiRrate configuration element from the Assignment Command message. "
+                           "Example: 28111a40. See 3GPP TS 44.018 - 10.5.2.21aa MultiRate configuration")
     tch_options.add_option("--voice-boundary", dest="enable_voice_boundary_detection", action="store_true", default=False,
                            help="Enable voice boundary detection for traffic channels. This can help reduce noice in the output.")
     parser.add_option_group(tch_options)
@@ -358,6 +390,8 @@ if __name__ == '__main__':
                           a5=options.a5, a5_kc=kc,
                           speech_file=options.speech_output_file, speech_codec=tch_codecs.get(options.speech_codec),
                           enable_voice_boundary_detection=options.enable_voice_boundary_detection,
+                          tch_h_channel=options.tch_h_channel,
+                          multi_rate=options.multi_rate,
                           verbose=options.verbose,
                           print_bursts=options.print_bursts, ppm=options.ppm)
 
diff --git a/grc/decoding/CMakeLists.txt b/grc/decoding/CMakeLists.txt
index 2f6eada..d488f21 100644
--- a/grc/decoding/CMakeLists.txt
+++ b/grc/decoding/CMakeLists.txt
@@ -19,5 +19,7 @@
 
 install(FILES
     gsm_control_channels_decoder.xml 
-    gsm_tch_f_decoder.xml DESTINATION share/gnuradio/grc/blocks
+    gsm_tch_f_decoder.xml
+    gsm_tch_h_decoder.xml
+    DESTINATION share/gnuradio/grc/blocks
 )
diff --git a/grc/decoding/gsm_tch_h_decoder.xml b/grc/decoding/gsm_tch_h_decoder.xml
new file mode 100644
index 0000000..895104e
--- /dev/null
+++ b/grc/decoding/gsm_tch_h_decoder.xml
@@ -0,0 +1,92 @@
+<?xml version="1.0"?>
+<block>
+  <name>TCH/H decoder</name>
+  <key>gsm_tch_h_decoder</key>
+  <import>import grgsm</import>
+  <make>grgsm.tch_h_decoder($sub_channel, $mode, $boundary_check)</make>
+
+  <param>
+    <name>sub-channel number</name>
+    <key>sub_channel</key>
+    <value>0</value>
+    <type>int</type>
+    <option>
+      <name>sub-channel 0</name>
+      <key>0</key>
+    </option>
+    <option>
+      <name>sub-channel 1</name>
+      <key>1</key>
+    </option>
+  </param>
+  <param>
+    <name>TCH/H coding mode</name>
+    <key>mode</key>
+    <type>enum</type>
+    <option>
+      <name>GSM-HS</name>
+      <key>grgsm.TCH_HS</key>
+    </option>
+    <option>
+      <name>GSM-AMR 7.95</name>
+      <key>grgsm.TCH_AHS7_95</key>
+    </option>
+    <option>
+      <name>GSM-AMR 7.4</name>
+      <key>grgsm.TCH_AHS7_4</key>
+    </option>
+    <option>
+      <name>GSM-AMR 6.7</name>
+      <key>grgsm.TCH_AHS6_7</key>
+    </option>
+    <option>
+      <name>GSM-AMR 5.9</name>
+      <key>grgsm.TCH_AHS5_9</key>
+    </option>
+    <option>
+      <name>GSM-AMR 5.15</name>
+      <key>grgsm.TCH_AHS5_15</key>
+    </option>
+    <option>
+      <name>GSM-AMR 4.75</name>
+      <key>grgsm.TCH_AHS4_75</key>
+    </option>
+  </param>
+  <param>
+    <name>Voice boundary detection</name>
+    <key>boundary_check</key>
+    <value>False</value>
+    <type>bool</type>
+    <option>
+      <name>False</name>
+      <key>False</key>
+    </option>
+    <option>
+      <name>True</name>
+      <key>True</key>
+    </option>
+  </param>
+  <check>$sub_channel() &gt; -1 and $sub_channel() &lt; 2</check>
+  <sink>
+    <name>bursts</name>
+    <type>message</type>
+  </sink>
+  <source>
+    <name>msgs</name>
+    <type>message</type>
+    <optional>1</optional>
+  </source>
+  <source>
+    <name>voice</name>
+    <type>message</type>
+    <optional>1</optional>
+  </source>
+
+  <doc>
+If "Voice boundary detection" is enabled, then only bursts are decoded as voice where
+
+- the framenumber is greater then the framenumber of a received "Connect" or "Connect Acknowlegde" message, and
+- the framenumber is less then the framenumber of a "Release" message
+  </doc>
+
+</block>
diff --git a/grc/gsm_block_tree.xml b/grc/gsm_block_tree.xml
index c2f59cd..1773df3 100644
--- a/grc/gsm_block_tree.xml
+++ b/grc/gsm_block_tree.xml
@@ -51,6 +51,7 @@
       <name>Decoding</name>
       <block>gsm_control_channels_decoder</block>
       <block>gsm_tch_f_decoder</block>
+      <block>gsm_tch_h_decoder</block>
     </cat>
     <cat>
       <name>Flow control</name>
diff --git a/include/grgsm/decoding/CMakeLists.txt b/include/grgsm/decoding/CMakeLists.txt
index 64bbb16..1014955 100644
--- a/include/grgsm/decoding/CMakeLists.txt
+++ b/include/grgsm/decoding/CMakeLists.txt
@@ -22,5 +22,7 @@
 ########################################################################
 install(FILES
     control_channels_decoder.h 
-    tch_f_decoder.h DESTINATION include/grgsm/decoding
+    tch_f_decoder.h
+    tch_h_decoder.h
+	DESTINATION include/grgsm/decoding
 )
diff --git a/include/grgsm/decoding/tch_f_decoder.h b/include/grgsm/decoding/tch_f_decoder.h
index df5f0ff..ae65f06 100644
--- a/include/grgsm/decoding/tch_f_decoder.h
+++ b/include/grgsm/decoding/tch_f_decoder.h
@@ -41,7 +41,8 @@ namespace gr {
         TCH_AFS5_15,
         TCH_AFS4_75,
         TCH_FS,
-        TCH_EFR
+        TCH_EFR,
+        TCH_HS,
     };
 
     /*!
diff --git a/include/grgsm/decoding/tch_h_decoder.h b/include/grgsm/decoding/tch_h_decoder.h
new file mode 100644
index 0000000..5ea9714
--- /dev/null
+++ b/include/grgsm/decoding/tch_h_decoder.h
@@ -0,0 +1,59 @@
+/* -*- c++ -*- */
+/*
+ * @file
+ * @author (C) 2018 by Vasil Velichkov <vvvelichkov@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.
+ */
+
+
+#ifndef INCLUDED_GSM_TCH_H_DECODER_H
+#define INCLUDED_GSM_TCH_H_DECODER_H
+
+#include <grgsm/api.h>
+#include <gnuradio/block.h>
+
+namespace gr {
+  namespace gsm {
+
+    /*!
+     * \brief <+description of block+>
+     * \ingroup gsm
+     *
+     */
+    class GRGSM_API tch_h_decoder : virtual public gr::block
+    {
+     public:
+      typedef boost::shared_ptr<tch_h_decoder> sptr;
+
+      /*!
+       * \brief Return a shared_ptr to a new instance of gsm::tch_h_decoder.
+       *
+       * To avoid accidental use of raw pointers, gsm::tch_h_decoder's
+       * constructor is in a private implementation
+       * class. gsm::tch_h_decoder::make is the public interface for
+       * creating new instances.
+       */
+      static sptr make(unsigned int sub_channel, std::string multi_rate, bool boundary_check=false);
+
+    };
+
+  } // namespace gsm
+} // namespace gr
+
+#endif /* INCLUDED_GSM_TCH_H_DECODER_H */
+
diff --git a/lib/decoding/CMakeLists.txt b/lib/decoding/CMakeLists.txt
index 154108a..423ab92 100644
--- a/lib/decoding/CMakeLists.txt
+++ b/lib/decoding/CMakeLists.txt
@@ -31,6 +31,7 @@ add_subdirectory(openbts)
 add_sources(
     control_channels_decoder_impl.cc
     tch_f_decoder_impl.cc
+    tch_h_decoder_impl.cc
     sch.c
 )
 
diff --git a/lib/decoding/tch_h_decoder_impl.cc b/lib/decoding/tch_h_decoder_impl.cc
new file mode 100644
index 0000000..b7672e3
--- /dev/null
+++ b/lib/decoding/tch_h_decoder_impl.cc
@@ -0,0 +1,357 @@
+/* -*- c++ -*- */
+/*
+ * @file
+ * @author (C) 2018 by Vasil Velichkov <vvvelichkov@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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <grgsm/gsmtap.h>
+#include "tch_h_decoder_impl.h"
+
+extern "C" {
+#include "osmocom/gsm/protocol/gsm_04_08.h"
+#include "osmocom/coding/gsm0503_coding.h"
+}
+
+namespace gr {
+    namespace gsm {
+
+        static int ubits2sbits(ubit_t *ubits, sbit_t *sbits, int count)
+        {
+            int i;
+
+            for (i = 0; i < count; i++) {
+                if (*ubits == 0x23) {
+                    ubits++;
+                    sbits++;
+                    continue;
+                }
+                if ((*ubits++) & 1)
+                    *sbits++ = -127;
+                else
+                    *sbits++ = 127;
+            }
+
+            return count;
+        }
+
+
+        tch_h_decoder::sptr
+        tch_h_decoder::make(unsigned int sub_channel, std::string multi_rate, bool boundary_check)
+        {
+            return gnuradio::get_initial_sptr
+                (new tch_h_decoder_impl(sub_channel, multi_rate, boundary_check));
+        }
+
+        /*
+         * Constructor
+         */
+        tch_h_decoder_impl::tch_h_decoder_impl(unsigned int sub_channel, std::string multi_rate, bool boundary_check)
+            : gr::block("tch_h_decoder",
+                    gr::io_signature::make(0, 0, 0),
+                    gr::io_signature::make(0, 0, 0)),
+            d_collected_bursts_num(0),
+            d_tch_mode(TCH_HS),
+            d_sub_channel(sub_channel),
+            d_boundary_check(boundary_check),
+            d_boundary_decode(false),
+            d_header_sent(false),
+            d_ft(0),
+            d_cmr(0)
+        {
+            //setup input/output ports
+            message_port_register_in(pmt::mp("bursts"));
+            set_msg_handler(pmt::mp("bursts"), boost::bind(&tch_h_decoder_impl::decode, this, _1));
+            message_port_register_out(pmt::mp("msgs"));
+            message_port_register_out(pmt::mp("voice"));
+
+            if(multi_rate.length())
+            {
+                std::cout<<"multi_rate configuration: "<<multi_rate<<std::endl;
+                if (multi_rate.length() < 4 || multi_rate.length() % 2)
+                {
+                    throw std::invalid_argument("Invalid multi_rate hexstring");
+                }
+
+                std::vector<uint8_t> binary;
+                for (std::string::const_iterator it = multi_rate.begin();
+                        it != multi_rate.end(); it += 2)
+                {
+                    std::string byte(it, it + 2);
+                    char* end = NULL;
+                    errno = 0;
+                    uint8_t b = strtoul(byte.c_str(), &end, 16);
+                    if (errno != 0 || *end != '\0')
+                    {
+                        throw std::invalid_argument("Invalid multi_rate hexstring");
+                    }
+                    binary.push_back(b);
+                }
+
+                if (binary.size() < 2) {
+                    throw std::invalid_argument("The multi_rate is too short");
+                }
+
+                //GSM A-I/F DTAP - Assignment Command
+                //    Protocol Discriminator: Radio Resources Management messages (6)
+                //    DTAP Radio Resources Management Message Type: Assignment Command (0x2e)
+                //    Channel Description 2 - Description of the First Channel, after time
+                //    Power Command
+                //    Channel Mode - Mode of the First Channel(Channel Set 1)
+                //    MultiRate configuration
+                //        Element ID: 0x03
+                //        Length: 4
+                //        001. .... = Multirate speech version: Adaptive Multirate speech version 1 (1)
+                //        ...0 .... = NSCB: Noise Suppression Control Bit: Noise Suppression can be used (default) (0)
+                //        .... 1... = ICMI: Initial Codec Mode Indicator: The initial codec mode is defined by the Start Mode field (1)
+                //        .... ..00 = Start Mode: 0
+                //        0... .... = 12,2 kbit/s codec rate: is not part of the subset
+                //        .0.. .... = 10,2 kbit/s codec rate: is not part of the subset
+                //        ..0. .... = 7,95 kbit/s codec rate: is not part of the subset
+                //        ...1 .... = 7,40 kbit/s codec rate: is part of the subset
+                //        .... 0... = 6,70 kbit/s codec rate: is not part of the subset
+                //        .... .0.. = 5,90 kbit/s codec rate: is not part of the subset
+                //        .... ..0. = 5,15 kbit/s codec rate: is not part of the subset
+                //        .... ...1 = 4,75 kbit/s codec rate: is part of the subset
+                //        ..01 1010 = AMR Threshold: 13.0 dB (26)
+                //        0100 .... = AMR Hysteresis: 2.0 dB (4)
+
+                const uint8_t first = binary[0];
+                uint8_t multirate_speech_ver = (first >> 5) & 0x07;
+                if (multirate_speech_ver == 1)
+                {
+                    d_tch_mode = TCH_AFS4_75;
+                }
+                else if (multirate_speech_ver == 2)
+                {
+                    throw std::invalid_argument("Adaptive Multirate speech version 2 is not supported");
+                }
+                else
+                {
+                    throw std::invalid_argument("Multirate speech version");
+                }
+
+                bool ncsb = (first >> 4) & 0x01;
+                bool icmi = (first >> 3) & 0x01;
+                uint8_t start = first & 0x03;
+
+                const uint8_t codecs = binary[1];
+                for (int i = 0; i < 8; i++)
+                {
+                    if ((codecs >> i) & 1)
+                    {
+                        d_multi_rate_codes.push_back(i);
+                    }
+                }
+
+                std::cout<<"Enabled AMR Codecs:"<<std::endl;
+                for(std::vector<uint8_t>::const_iterator it = d_multi_rate_codes.begin();
+                        it != d_multi_rate_codes.end();
+                        it ++)
+                {
+                    switch(*it)
+                    {
+                        case 0:
+                            std::cout<<"4,75 kbit/s codec rate: is part of the subset"<<std::endl;
+                            break;
+                        case 1:
+                            std::cout<<"5,15 kbit/s codec rate: is part of the subset"<<std::endl;
+                            break;
+                        case 2:
+                            std::cout<<"6,90 kbit/s codec rate: is part of the subset"<<std::endl;
+                            break;
+                        case 3:
+                            std::cout<<"6,70 kbit/s codec rate: is part of the subset"<<std::endl;
+                            break;
+                        case 4:
+                            std::cout<<"7,40 kbit/s codec rate: is part of the subset"<<std::endl;
+                            break;
+                        case 5:
+                            std::cout<<"7,95 kbit/s codec rate: is part of the subset"<<std::endl;
+                            break;
+                        case 6:
+                            std::cout<<"12,2 kbit/s codec rate: is part of the subset"<<std::endl;
+                    }
+                }
+                if (d_multi_rate_codes.size() > 4) {
+                    throw std::invalid_argument("More then 4 multirate codes");
+                }
+            }
+        }
+
+        tch_h_decoder_impl::~tch_h_decoder_impl()
+        {
+        }
+
+        void tch_h_decoder_impl::decode(pmt::pmt_t msg)
+        {
+            d_bursts[d_collected_bursts_num++] = msg;
+            if (d_collected_bursts_num <= 7)
+            {
+                return;
+            }
+
+            gsmtap_hdr* header = (gsmtap_hdr*)(pmt::blob_data(pmt::cdr(msg)));
+            uint32_t frame_nr = be32toh(header->frame_number);
+            bool uplink_burst = (be16toh(header->arfcn) & 0x4000) ? true : false;
+
+            //TODO: Check in 3gpp specs which frames could contains facch/h frames
+            //and replace this ugly formula with table
+            int fn_is_odd = (((frame_nr - (uplink_burst ? 10 : 15)) % 26) >> 2) & 1;
+
+            ubit_t bursts_u[116 * 6] = {0}; //facch/h is 6 bursts
+
+            //reorganize data
+            for (int ii = 0; ii < 8; ii++)
+            {
+                //skip the 4th and 5th bursts
+                if (ii == 4 || ii == 5) continue;
+
+                int8_t* burst_bits = (int8_t*)(pmt::blob_data(pmt::cdr(d_bursts[ii])))+sizeof(gsmtap_hdr);
+
+                //copy 6th and 7th burst to 4th and 5th position
+                int n = ii < 6 ? ii : ii - 2;
+
+                memcpy(&bursts_u[n*116], &burst_bits[3],58);
+                memcpy(&bursts_u[n*116+58], &burst_bits[3+57+1+26],58);
+            }
+
+            //Convert to sbits
+            sbit_t bursts_s[116 * 6] = {0};
+            ubits2sbits(bursts_u, bursts_s, 116 * 6);
+
+            //Prepare burst for the next iteration by shifting them by 4
+            for (int ii = 0; ii < 4; ii++) {
+                d_bursts[ii] = d_bursts[ii + 4];
+            }
+            d_collected_bursts_num = 4;
+
+            uint8_t frameBuffer[64];
+            int frameLength = -1;
+            int n_errors, n_bits_total;
+
+            if (d_tch_mode == TCH_HS)
+            {
+                frameLength = gsm0503_tch_hr_decode(frameBuffer, bursts_s, fn_is_odd, &n_errors, &n_bits_total);
+            }
+            else
+            {
+                frameLength = gsm0503_tch_ahs_decode(frameBuffer, bursts_s, fn_is_odd,
+                        fn_is_odd, //int codec_mode_req,
+                        &d_multi_rate_codes.front(), d_multi_rate_codes.size(),
+                        &d_ft,
+                        &d_cmr,
+                        &n_errors, &n_bits_total);
+            }
+
+            if (frameLength < 12)
+            {
+                if (!d_boundary_check || d_boundary_decode) {
+                    std::cerr<<"Error! frame_nr:"<<frame_nr<<" mod26:"<<frame_nr%26
+                        <<" fn_is_odd:"<<fn_is_odd<<" length:"<<frameLength<<std::endl;
+                }
+                return;
+            }
+            else if (frameLength == GSM_MACBLOCK_LEN) //FACCH/H
+            {
+                pmt::pmt_t first_header_plus_burst = pmt::cdr(d_bursts[0]);
+                gsmtap_hdr* header = (gsmtap_hdr *)pmt::blob_data(first_header_plus_burst);
+                int8_t header_plus_data[sizeof(gsmtap_hdr)+frameLength];
+                memcpy(header_plus_data, header, sizeof(gsmtap_hdr));
+                memcpy(header_plus_data+sizeof(gsmtap_hdr), frameBuffer, frameLength);
+                ((gsmtap_hdr*)header_plus_data)->type = GSMTAP_TYPE_UM;
+
+                pmt::pmt_t msg_binary_blob = pmt::make_blob(header_plus_data, frameLength + sizeof(gsmtap_hdr));
+                pmt::pmt_t msg_out = pmt::cons(pmt::PMT_NIL, msg_binary_blob);
+
+                message_port_pub(pmt::mp("msgs"), msg_out);
+
+                // if d_boundary_check is enabled, we set d_boundary_decode to true, when a
+                // "Connect" or "Connect Acknowledge" message is received, and
+                // we set d_boundary_decode back to false, when "Release" message is received
+                if (d_boundary_check)
+                {
+                    // check if this is a call control message
+                    if ((frameBuffer[3] & 0x0f) == 0x03)
+                    {
+                        // Connect specified in GSM 04.08, 9.3.5
+                        if ((frameBuffer[4] & 0x3f) == 0x07)
+                        {
+                            d_boundary_decode = true;
+                        }
+                        // Connect Acknowledge specified in GSM 04.08, 9.3.6
+                        else if ((frameBuffer[4] & 0x3f) == 0x0f)
+                        {
+                            d_boundary_decode = true;
+                        }
+                        // Release specified in GSM 04.08, 9.3.18
+                        else if ((frameBuffer[4] & 0x3f) == 0x2d)
+                        {
+                            d_boundary_decode = false;
+                        }
+                    }
+                }
+                return;
+            }
+
+            if (!d_header_sent && d_tch_mode != TCH_HS)
+            {
+                const unsigned char amr_nb_magic[7] = "#!AMR\n";
+                message_port_pub(pmt::mp("voice"), pmt::cons(pmt::PMT_NIL, pmt::make_blob(amr_nb_magic, 6)));
+                d_header_sent = true;
+            }
+
+            if (!n_errors && (!d_boundary_check || d_boundary_decode))
+            {
+                //std::cerr<<"Voice frame_nr:"<<frame_nr<<" mod26:"<<frame_nr%26<<" is_odd:"<<fn_is_odd
+                //    <<" type:"<<(uint32_t)d_ft<<" cmr:"<<(uint32_t)d_cmr
+                //    <<" errors:"<<n_errors<<std::endl;
+
+                if (d_tch_mode != TCH_HS)
+                {
+                    //Move one byte to make space for the header
+                    memmove(frameBuffer + 1, frameBuffer, frameLength);
+                    //Add the AMR header
+                    switch(frameLength)
+                    {
+                        case 12: frameBuffer[0] = (0 << 3); break; //TCH/AHS4.75
+                        case 13: frameBuffer[0] = (1 << 3); break; //TCH/AHS5.15
+                        case 15: frameBuffer[0] = (2 << 3); break; //TCH/AHS5.9
+                        case 17: frameBuffer[0] = (3 << 3); break; //TCH/AHS6.7
+                        case 19: frameBuffer[0] = (4 << 3); break; //TCH/AHS7.4
+                        case 20: frameBuffer[0] = (5 << 3); break; //TCH/AHS7.95
+                        default: std::cerr<<"Unexpected voice frame length:"<<frameLength<<std::endl; return;
+                    }
+                    frameLength += 1;
+                }
+
+                //std::ostringstream out;
+                //out << "voice frame: ";
+                //for (int i = 0; i < frameLength; i++)
+                //    out << " " << (std::hex) << std::setw(2) << std::setfill('0') << (uint32_t)*(frameBuffer + i);
+                //std::cerr << out.str() << std::endl;
+                message_port_pub(pmt::mp("voice"), pmt::cons(pmt::PMT_NIL, pmt::make_blob(frameBuffer, frameLength)));
+            }
+        }
+    } /* namespace gsm */
+} /* namespace gr */
+
diff --git a/lib/decoding/tch_h_decoder_impl.h b/lib/decoding/tch_h_decoder_impl.h
new file mode 100644
index 0000000..902b216
--- /dev/null
+++ b/lib/decoding/tch_h_decoder_impl.h
@@ -0,0 +1,60 @@
+/* -*- c++ -*- */
+/*
+ * @file
+ * @author (C) 2018 by Vasil Velichkov <vvvelichkov@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.
+ */
+
+#ifndef INCLUDED_GSM_TCH_H_DECODER_IMPL_H
+#define INCLUDED_GSM_TCH_H_DECODER_IMPL_H
+
+#include <grgsm/decoding/tch_h_decoder.h>
+#include "tch_f_decoder_impl.h"
+
+namespace gr {
+    namespace gsm {
+
+        class tch_h_decoder_impl : public tch_h_decoder
+        {
+            private:
+                unsigned int d_collected_bursts_num;
+                pmt::pmt_t d_bursts[8];
+
+                enum tch_mode d_tch_mode;
+                unsigned int d_sub_channel;
+
+                std::vector<uint8_t> d_multi_rate_codes;
+
+                bool d_boundary_check;
+                bool d_boundary_decode;
+                bool d_header_sent;
+
+                uint8_t d_ft;
+                uint8_t d_cmr;
+
+                void decode(pmt::pmt_t msg);
+            public:
+                tch_h_decoder_impl(unsigned int sub_channel, std::string multi_rate, bool boundary_check=false);
+                ~tch_h_decoder_impl();
+        };
+
+    } // namespace gsm
+} // namespace gr
+
+#endif /* INCLUDED_GSM_TCH_H_DECODER_IMPL_H */
+
diff --git a/lib/demapping/tch_h_chans_demapper_impl.cc b/lib/demapping/tch_h_chans_demapper_impl.cc
index 2c3dc79..73f49e1 100644
--- a/lib/demapping/tch_h_chans_demapper_impl.cc
+++ b/lib/demapping/tch_h_chans_demapper_impl.cc
@@ -87,6 +87,7 @@ void tch_h_chans_demapper_impl::filter_tch_chans(pmt::pmt_t msg)
     memcpy(new_msg, header, sizeof(gsmtap_hdr)+BURST_SIZE);
 
     new_hdr->sub_type = (fn_mod13 == 12 ? GSMTAP_CHANNEL_ACCH : 0) | GSMTAP_CHANNEL_TCH_H;
+    new_hdr->sub_slot = d_tch_h_channel;
 
     pmt::pmt_t msg_binary_blob = pmt::make_blob(new_msg,sizeof(gsmtap_hdr)+BURST_SIZE);
     pmt::pmt_t msg_out = pmt::cons(pmt::PMT_NIL, msg_binary_blob);
diff --git a/swig/grgsm_swig.i b/swig/grgsm_swig.i
index 5f06eb3..8035dc5 100644
--- a/swig/grgsm_swig.i
+++ b/swig/grgsm_swig.i
@@ -38,6 +38,7 @@
 #include "grgsm/receiver/cx_channel_hopper.h"
 #include "grgsm/decoding/control_channels_decoder.h"
 #include "grgsm/decoding/tch_f_decoder.h"
+#include "grgsm/decoding/tch_h_decoder.h"
 #include "grgsm/decryption/decryption.h"
 #include "grgsm/demapping/universal_ctrl_chans_demapper.h"
 #include "grgsm/demapping/tch_f_chans_demapper.h"
@@ -92,6 +93,8 @@ GR_SWIG_BLOCK_MAGIC2(gsm, cx_channel_hopper);
 GR_SWIG_BLOCK_MAGIC2(gsm, control_channels_decoder);
 %include "grgsm/decoding/tch_f_decoder.h"
 GR_SWIG_BLOCK_MAGIC2(gsm, tch_f_decoder);
+%include "grgsm/decoding/tch_h_decoder.h"
+GR_SWIG_BLOCK_MAGIC2(gsm, tch_h_decoder);
 
 %include "grgsm/decryption/decryption.h"
 GR_SWIG_BLOCK_MAGIC2(gsm, decryption);