DSD

Discussion on P25
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kb9mwr
Posts: 86
Joined: Tue Dec 03, 2013 10:59 am

DSD

Post by kb9mwr » Wed Jan 01, 2014 7:35 pm

For anyone who hasn't played with Digital voice, there is a very handy software tool called Digital Speech Decoder that can decode a variety of digital formats.

Several years ago I stumbled into it. And the only thing that was digital at the time in the area was St. Vincent's hosipital, then later UWGB public safety.

You take the discriminator audio from your analog radio (available on the data port of many mobile ham rigs) and feed it into the sound card input.

It allows you to listen to popular formats like; P25/APCO25, DMR/Mototrbo, D-Star, IDAS/NXDN.

https://github.com/szechyjs/dsd

Here is what I did to install it on Ubuntu 10.04 :

Code: Select all

apt-get install libsndfile-dev cmake
apt-get install build-essential libssl-dev curl git-core
git clone https://github.com/szechyjs/mbelib.git
git clone https://github.com/szechyjs/dsd.git
cd mbelib
mkdir build
cd build
cmake ..
make
make install
cd
cd dsd
mkdir build
cd build
cmake ..
make
make install
ldconfig   
root@tlb:/dev# dsd -i /dev/dsp -o /dev/dsp
Digital Speech Decoder 1.7.0-dev (build:v1.6.0-26-ge40e89a)
mbelib version 1.2.5
Audio In/Out Device: /dev/dsp
The audio recreation part (mbelib) isn't very smooth on a pi, as its a bit underpowered. So use a normal computer

There are hourly time P25 annoucements on the output of Matt's repeater 147.435.. if you need a signal to try and decode.

http://www.youtube.com/watch?v=wzSaIOZmo0U

kb9mwr
Posts: 86
Joined: Tue Dec 03, 2013 10:59 am

Re: DSD

Post by kb9mwr » Fri Mar 21, 2014 12:55 pm

http://forums.radioreference.com/digita ... r-dsd.html

Hi All,

Just for fun I threw together a repeater program in c# that works on Windows 7/8. It also sets the RTS/DTR (or both) pins high when transmitting the audio.

I wanted to make the repeater only transmit if a certain nac is decoded rather than setting audio levels. Since i'm not as smart as the people working on DSD+ or OP25, I decided to go another direction.

After some reading, I managed to grab the text output from DSD+ while it's decoding, search through each line as it comes in, and transmit based on the NAC it decodes


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