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Added more pilot symbols for precision frequency estimation

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This adds 4 pilot symbols each after 128 and 256 data symbols. These are
used for precision frequency estimation and feed-forward correction,
resulting in less decoder errors at the end of the packet.

Due to this change, this system can no longer transmit packets shorter
than 64 bytes!
This commit is contained in:
Thomas Kolb 2019-09-13 23:10:23 +02:00
commit 85ce667d7b
18 changed files with 903 additions and 20 deletions
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125
tmp/test_sc16qam.grc
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@ -105,7 +105,7 @@
</param>
<param>
<key>_coordinate</key>
<value>(957, 394)</value>
<value>(974, 51)</value>
</param>
<param>
<key>gui_hint</key>
@ -168,7 +168,7 @@
</param>
<param>
<key>_coordinate</key>
<value>(837, 394)</value>
<value>(854, 51)</value>
</param>
<param>
<key>gui_hint</key>
@ -258,7 +258,7 @@
</param>
<param>
<key>_enabled</key>
<value>True</value>
<value>1</value>
</param>
<param>
<key>_coordinate</key>
@ -1355,6 +1355,105 @@
<value>firdes.WIN_BLACKMAN_hARRIS</value>
</param>
</block>
<block>
<key>qtgui_sink_x</key>
<param>
<key>bw</key>
<value>samp_rate/2</value>
</param>
<param>
<key>alias</key>
<value></value>
</param>
<param>
<key>fc</key>
<value>0</value>
</param>
<param>
<key>freqchangevar</key>
<value>None</value>
</param>
<param>
<key>comment</key>
<value></value>
</param>
<param>
<key>affinity</key>
<value></value>
</param>
<param>
<key>_enabled</key>
<value>0</value>
</param>
<param>
<key>fftsize</key>
<value>8192</value>
</param>
<param>
<key>_coordinate</key>
<value>(694, 554)</value>
</param>
<param>
<key>gui_hint</key>
<value></value>
</param>
<param>
<key>_rotation</key>
<value>0</value>
</param>
<param>
<key>id</key>
<value>qtgui_sink_x_1</value>
</param>
<param>
<key>maxoutbuf</key>
<value>0</value>
</param>
<param>
<key>minoutbuf</key>
<value>0</value>
</param>
<param>
<key>name</key>
<value>"Synced Symbols"</value>
</param>
<param>
<key>plotconst</key>
<value>True</value>
</param>
<param>
<key>plotfreq</key>
<value>True</value>
</param>
<param>
<key>plottime</key>
<value>True</value>
</param>
<param>
<key>plotwaterfall</key>
<value>True</value>
</param>
<param>
<key>showports</key>
<value>True</value>
</param>
<param>
<key>showrf</key>
<value>False</value>
</param>
<param>
<key>type</key>
<value>complex</value>
</param>
<param>
<key>rate</key>
<value>1</value>
</param>
<param>
<key>wintype</key>
<value>firdes.WIN_BLACKMAN_hARRIS</value>
</param>
</block>
<block>
<key>qtgui_time_sink_x</key>
<param>
@ -1391,7 +1490,7 @@
</param>
<param>
<key>_coordinate</key>
<value>(710, 562)</value>
<value>(870, 487)</value>
</param>
<param>
<key>gui_hint</key>
@ -1655,7 +1754,7 @@
</param>
<param>
<key>name</key>
<value>""</value>
<value>"Synced"</value>
</param>
<param>
<key>nconnections</key>
@ -1663,11 +1762,11 @@
</param>
<param>
<key>size</key>
<value>1024</value>
<value>8192</value>
</param>
<param>
<key>srate</key>
<value>samp_rate</value>
<value>samp_rate/2</value>
</param>
<param>
<key>stemplot</key>
@ -1695,7 +1794,7 @@
</param>
<param>
<key>tr_tag</key>
<value>"corr_est"</value>
<value>"corr_start"</value>
</param>
<param>
<key>type</key>
@ -1703,7 +1802,7 @@
</param>
<param>
<key>update_time</key>
<value>0.10</value>
<value>1</value>
</param>
<param>
<key>ylabel</key>
@ -1754,7 +1853,7 @@
</param>
<param>
<key>_enabled</key>
<value>True</value>
<value>1</value>
</param>
<param>
<key>_coordinate</key>
@ -2155,6 +2254,12 @@
<source_key>pdu_out</source_key>
<sink_key>print_pdu</sink_key>
</connection>
<connection>
<source_block_id>hamnet70_demod_sc16qam_0</source_block_id>
<sink_block_id>qtgui_sink_x_1</sink_block_id>
<source_key>1</source_key>
<sink_key>0</sink_key>
</connection>
<connection>
<source_block_id>hamnet70_demod_sc16qam_0</source_block_id>
<sink_block_id>qtgui_time_sink_x_0</sink_block_id>