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--- project:sdr:tetra:howto [2016/09/12 17:18] – [Setup] tweak non-integer sps jenda
+++ project:sdr:tetra:howto [2017/04/05 15:17] – [Building] jenda
@@ Line 8: / Line 8: @@
 {{ :project:sdr:tetra:tetra.png?direct&300 |}}
+<note important>We suspect there is a bug in airspy_rx with sample format 0. After several minutes, it sends us a NaN. The workaround (if you want to use Airspy) is to use osmosdr-input from [[:user:jenda:kukuruku]].</note>
 ===== Requirements =====
@@ Line 37: / Line 39: @@
 ===== Building =====
-Install jcc from blobutils to your %%$%%PATH and run build.sh to get gr-pack and gr-unpack; get them to your %%$%%PATH too.
+Install jcf from blobutils to your %%$%%PATH and run build.sh to get gr-pack and gr-unpack; get them to your %%$%%PATH too.
-Install libosmocore (autoreconf -i && ./configure && make && make install).
+Install libosmocore-dev package (Ubuntu 16.10+, Debian 9+) or build libosmocore by hand (autoreconf -i && ./configure --disable-pcsc && make && make install).
 Build tetra-listener (instructions are in README).
@@ Line 72: / Line 74: @@
 Run it and use gethisto FCL command (echo gethisto | nc localhost 3333) to get sane gain settings.
-Use getpwr command to get channel power and sort the results (echo getpwr | nc localhost 3333 | sort -nk 2). A better approach would be to oversample the spectrum reading by 4 and take only the 2 middle bins.
+You can use this oneliner to get the list of 20 strongest channels:
+<code>
+echo getpwr 3 | nc localhost 3333 | while read line; do n=`echo $line | cut -d " " -f 1`; if [ $(( ( $n - 1 ) % 3 )) -eq 0 ]; then echo $(( ($n - 1) / 3)) `echo $line | cut -d " " -f 2`; fi;done | LANG=C sort -nk 2 | tail -n 20 | cut -d " " -f 1 | tr "\n" ,
+</code>
 Edit enabled channels in tetra-run.sh so they match your channels with the strongest power. Do not enable more than 30 channels per SDR (or change the offset in tetra2.py:128).
@@ Line 87: / Line 92: @@
 It can be useful to check after a day or so which channels produce audio data (ls|grep bz2|cut -d "o" -f 2|cut -d "." -f 1|sort -n | uniq -c) and change the ones that do not for some new channels.
+You may want to add ".timeout 5000" to your ~/.sqliterc.