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README.md

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 # M17_Implementations
 Various implementations
+
+## SP5WWP's implementation (/sp5wwp)
+### Overview
+Written in C, it has all the components described by the protocol's specification of the stream mode:
+- convolutional encoder with soft Vitrerbi decoder (utilizing fixed point arithmetic),
+- Golay encoder with soft decoder (fixed point),
+- bit interleaver and randomizer
+There's no support for **any** encryption yet.
+
+### Building
+Simply `cd` to the directory of interest and
+```make```
+
+### Capabilities
+Two executables are available:
+- `m17-coder-sym` is used to convert a raw binary data bitstream to symbols. Symbol stream has to be
+filtered with an appropriate filter vefore transmission, see the specification document for details.
+- `m17-decoder-sym` decodes a stream of floats at `stdin`, one sample per symbol. After a valid
+syncword is detected, decoding process starts. The program expects a stream of synchronized symbols
+at the input. See the `/grc/m17_streamer.grc` file for details.
+
+### Testing
+Both the encoder and the decoder can be tested simultaneously. The test setup should look as follows:<br>
+`GRC flowgraph -> fifo1 -> m17-coder-sym -> fifo2 -> m17-decoder-sym -> stdout`<br>
+To perform a simple test, GNURadio 3.10 is required.
+
+Run the following commands:
+```
+mkfifo fifo1
+mkfifo fifo2
+```
+This should create 2 named pipes: `fifo1` and `fifo2`. The first one is used for the "transmitted" raw
+bitstream from GNURadio. The other one is used for the "receiver" part - the symbol stream.
+
+Start gnuradio-companion, open the .grc file included in this repo (`/grc/m17_streamer.grc`) and change
+the name of the named pipe to `fifo1` (at the *File Sink* block - the rightmost one). Change the location of it
+if needed.
+
+Open up 2 consoles and run:<br>
+Console 1:
+```
+cat fifo1 | ./m17-coder-sym > fifo2
+```
+Console 2:
+```
+cat fifo2 | ./m17-decoder-sym
+```