How to build a Digital Voice Transcoding Server with ambed

NW Digital Radio, AMBE ThumbDV3000
NW Digital Radio, AMBE ThumbDV3000

What is a transcoding server?

A transcoding server is a linux computer running special software that can input one digital mode and output a different mode. Whether you know it or not, the bain of the digital voice existence today is the fact, digital voice modes can’t communicate with each other. If you have a DMR radio sitting next to a D-Star radio, the 2 can only communicate via their analog mode, not their respective digital mode. With some open source software and any computer that can run linux, specifically Debian or a Raspberry Pi, you can merge different modes together. With a Transcoding server connected via the network to a Reflector, you can cross modes with people all around the world, helping break down the barrier of entry into the digital world.

Whats involved:

  • Having a ready to go Debian computer that is up to date and online.
  • Purchasing USB AMBE computer Chips
    • Yes, its true, you MUST have these in order for this to work, minimum of 2(for 2 channels).
    • Currently the only easiest place to really get these are from North West Digital Radio for $90 each. *when on special
  • Build a XLX reflector using the same software, even on the same computer, if you dont already have one, then connecting the two services. How-to Here.
  • Linux commands to compile software along with editing files
  • Firewall port openings on network gateway devices like routers.

Why so much work??

The AMBE chip is an “open standard” that companies can build on. This means, big companies like Motorola can hire software and hardware engineers and build a radio around this chip. Since the dawn of digital voice, a few select hams have taken the time to build this software for the community already for us. Because digital voice is basically computer data, it blends “easily” with human readable computing and at the core, is the AMBE chip. To build something from the ground up, you need to learn and know programming languages like C, C++, have deep electrical engineering level knowledge on how to interface with the ambe chip, then be able to interface it easily with a computer, say over usb. To be able to write a relatively simple how to article is a blessing in disguise for the ham community. Most of the leg work has been done already, the hardware made, the software written, now all you have to do is, put it all together. Next time you see any of those folks, please shake their hand and thank them.

Before you get started with this tutorial, have the following ready:

  1. A Debian Linux computer running and online
  2. Plug the USB AMBE chips into the server
  3. You can choose to either install XLX and AMBE together or separate them over the network. If you go the network route, make sure both places can talk over UDP 10100.
  4. Patience.

 

Step-by-Step Guide coming…….

***Instead, I used the time to build an install script for ambed on Debian 8 and 9.***

ambed-debian-installer script

 

References:

Link for instructions on installing FTDI Driver:
https://www.ftdichip.com/Drivers/D2XX/Linux/ReadMe-linux.txt

NW-Digital-Radio Message Board:
https://nw-digital-radio.groups.io/g/ambe/topics

ambed install instructions:
https://github.com/LX3JL/xlxd/blob/master/ambed/readme

 

Updated: 9-24-2018