As discussed the link hub software uses the USRP protocol for audio and control packets. The current USRP driver in Allstar is lacking in several areas for implementing digital linking, including:
- Header packets that contains repeater ID, radio ID and callsign information
- Full implementation of the packet header to include talk group data
- The ability to specify and modify an outbound talk group with a DTMF command
- A response to a ping packet for link validation and ‘keep alive’
- Useful debugging information
- Configuration files for digital network data
- ULAW and ADPCM voice packet types, although defined in the protocol
- DTMF packets in and out
A new channel driver, called ‘chan_ddl’ has been developed for this purpose. It can easily be installed in the allstar/asterisk system, and can support up to 32 nodes, each of which can be a unique talkgroup. The standard connection mechanism is used to determine the talkgroup to be used.
The documentation is below, to obtain a copy, please contact me through the contacts page.