Differences

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--- project:sdr:squelchcut [2012/08/09 13:30] – created jenda
+++ project:sdr:squelchcut [2012/08/09 13:30] (current) – [Detecting] jenda
@@ Line 1: / Line 1: @@
+====== Silence detection and timestamping ======
+Imagine there is something like civil band radio and you want to run some software overnight and have conversations logged like this:
+<code>
+-rw-r--r--  1 jenda jenda 183k rec-2012-08-08-18-37-37.ogg
+-rw-r--r--  1 jenda jenda  98k rec-2012-08-08-18-41-49.ogg
+-rw-r--r--  1 jenda jenda 100k rec-2012-08-08-18-47-35.ogg
+-rw-r--r--  1 jenda jenda 200k rec-2012-08-08-18-54-52.ogg
+</code>
+We will use one computer for receiving and another for splitting based on silence detection.
+==== Receiving ====
+gnuradio-companion sketch is [[http://jenda.hrach.eu/brm/rad/nbfm_rx.grc|here]]. It receives narrow-band FM, but changing it for other modulations should be easy.
+Create a pipe, run netcat to transmit data over the network and run the gnuradio program.
+<code>
+mkfifo test.wav
+cat test.wav | nc 192.168.77.226 3333 &
+./top_block.py
+</code>
+==== Detecting ====
+On the other end (well, you can run everything on one computer just by piping it instead of using netcat) download and compile [[http://jenda.hrach.eu/brm/rad/squelch-cut.c|squelch-cut.c]] and run it like
+<code>nc -l -p 3333 | ./a.out</code>
+WAV (they are actually RAW) files should appear in current working directory after the first transmission occurs.
+Use oggenc to encode them to some more common format.
+<code>oggenc -r -C 1 --raw-endianness 1 rec-*.wav</code>