tcd

tcd is a hybrid digital voice transcoder for ham radio used by the new URF reflector.

Introduction

This will build a new kind of hybrid transcoder that uses AMBE DVSI-based hardware for vocoding digital voice streams used in DStar/DMR/YSF and David Rowe's open-source Codec2 used in M17. TCd is optimized for performance by using a highly multi-threaded design that incorporates blocking I/O to make it as efficient as possible.

This is the only transcoder that will work with the URF reflector.

This software is loosely based on LX3JL's ambed, but is easily different enough to be considered an entirely original work. Here are some major differences with ambed:

• tcd uses both hardware-based and software-based vocoders, providing a bridge between the closed source vocoders used in DStar, DMR and YSF and open-source vocoders used in M17.
• UNIX Sockets are used to communicate between the reflector and this transcoder. This greatly simplifies the code and significantly improves transcoding performance.
• AMBE vocoders are dedicated to an assigned reflector channel. This prevents overloading when processing multiple voice streams and provides the best possible performance for the reflector's clients.

Constraints and Requirements

Currently, only two AMBE devices are supported. You cannot use a 3003 and a 3000 device together. If you use a pair of 3000 devices, only 460800-baud deivces are supported. When using a pair of 3000 devices, you can only transcode a single channel. If you use a pair of 3003 devices, you can specify up to three transcoded channels. AMBE devices based on LX3JL's USB-3006 open source design (sold by Northwest Digital and others) contain a pair of 3003 devices and are ideally suited for tcd.

Currently, this program must be run locally with its paired URF reflector. Remote transcoding is not yet possible.

Only systemd-based operating systems are supported. Debian or Ubuntu is recommended. If you want to install this on a non-systemd based OS, you are on your own. Also, by default, tcd is built without gdb support.

Download the repository

In the parent directory of you urfd repository:

git clone https://github.com/n7tae/tcd.git

To be perfectly clear, the urfd reflector repository clone and this clone must be in the same directory.

Configuring, compiling, installing and other activities

All other activities will be performed by the ./rconfig and ./radmin scripts in your urfd repo.

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DE N7TAE