Digital Voice Transceiver Project

This Project began to explore the use of the DVSI AMBE 2020 voice compression chip and also the ADF7021 single chip VHF  RF Transceiver from Analog Devices.  It appeared that this radio could be made to talk D-Star and that turned into yet another adventure trying to fill in the many holes in the published "Open" D-Star Specification.  From there it turned into a nearly complete D-Star format 2 meter transceiver.  A paper on this project was presented at the SVHFS Conference in Atlanta on April 28, 2007. Link to SVHS web site

Below are some photos of the "Guts" of the experimental radio.


A link to a paper describing this project in more detail.
DVX Project Paper(1.8Meg .pdf)

Experimenter Board Schematic:

DVX Demo Source Code:

Note: This project was a proof of concept project and as such is NOT USEFUL AS A DSTAR RADIO.  There are several problems with the design, the biggest is the inability of the Analog Devices RF transceiver chip to lock onto the data in time to get the header packet.  So far no resolution of the issue has been found. 

*** 2009-08-15     A resolution to the data locking has been found involving some code changes as well as a new -L version of the Analog Devices chip.  This project in its present form is still not a viable radio due to sensitivity/selectivity and power limitations.

Future Directions:

The most likely direction is a re-spin of the board to add more user inputs like a key pad as well as split the RF section onto another board and add preamp and PA. 

Another output from this project will be a more detailed low level D-Star format description and open source code that others can use or build upon for their own projects.