WA Radio Scanner Users' Group

Posted: **Sat Nov 09, 2019 11:33 am**

Guide for setting up POCSAG decoder on Linux
Tested on Ubuntu 18.04.3 and macOS 10.15 Catalina with an RTL820T2 SDR.

1.

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sudo apt update

2.

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sudo apt install rtl_sdr netcat sox gqrx

3. Clone this repository to the home folder

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git clone https://github.com/EliasOenal/multimon-ng.git

and cd into it
4. To build multimon-ng, follow these instructuctions, you will need make installed.

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mkdir build
cd build
cmake ..
make
sudo make install

5. Launch GQRX and go to Tools>Remote Control Settings and set the port to 7355, and add localhost to the allowed hosts list.
6. Attach your SDR and make sure GQRX is getting data, then tune to your intended paging frequency.
7. Click the UDP button, located near the bottom right of the GQRX window.
You'll want to set the Filter Width to about 11k and the mode to NFM, don't enable any noise blankers or AGC.
8. Launch the terminal and paste

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nc -l -u localhost 7355 |     sox -t raw -esigned-integer -b 16 -r 48000 - -esigned-integer -b 16 -r 22050 -t raw - |     multimon-ng -t raw -a POCSAG512 -a POCSAG1200 -a POCSAG2400  -f alpha -

8. If all has worked correctly, once GQRX recieves a signal, which will appear in the waterfall as 2 streams of data, multimon-ng will start to decode them.

You may need to adjust some of the reciever settings to get a good signal, but it should work fine.

Posted: **Sat Nov 09, 2019 4:11 pm**

Nice.
2400 baud doesn't appear to be used on Australian networks so you'd get a bit of a performance boost by not having Multimon try to decode it.

Posted: **Fri Dec 06, 2019 10:28 pm**

Works for me. Thanks!

Posted: **Sun Dec 08, 2019 11:22 am**

No problem! If anyone would like it as well, I could post a guide for decoding digital modes with GQRX and DSD on linux too.

Also if you need to tune your SDR's frequency correction, I normally put my CB on 25, or 477.025, key up once I put GQRX onto 477.025 and just adjust the correction until the frequency matches up with the waterfall output.

Posted: **Fri Dec 13, 2019 8:56 pm**

Or you can just use an FM radio station...

Mine still drifts due to temperature. It's time to get a proper SDR reciever.

Posted: **Sun Dec 15, 2019 6:15 pm**

I didn't even consider that, that's a much better idea.

WA Radio Scanner Users' Group

Guide to decoding POCSAG on Linux

Guide to decoding POCSAG on Linux

Re: Guide to decoding POCSAG on Linux

Re: Guide to decoding POCSAG on Linux

Re: Guide to decoding POCSAG on Linux

Re: Guide to decoding POCSAG on Linux

Re: Guide to decoding POCSAG on Linux