Phone and Voice Node
This node is actually two small boxes. One houses the text to speech converter, and the other the various phone interfaces.
Text to Speech ConverterThis unit was purchased from a commercialy company called RC systems. I found their add in the back of Circuit Cellar Ink. I wanted a unit that did not have a prerecorded vocabulary like the DigiTalker DT1050 from National Semiconductor. The RC Systems unit can accept a serial or parallel (PC printer) port type of interface. I decided to wire up the parallel port version because it allows the most flexibility. The speech quality is quite good, but one can definitely tell that it is synthetic. The box has a speaker output, and the output is also routed to one of the unused pins on the parallel port connector. Another pin on this port also controls an internal relay that switches the destination of the spoken sound. This allows the phone interface to inject the sound into the phone line, or allow it to be broadcast by speaker.
The unit was about $150 from RC Systems in Everett, WA.
The Phone InterfaceThe phone interface is capable of the following:
- Generating DTMF (touch tone) signals
- Decoding DTMF signals
- Decoding Caller ID signals
- Taking the phone off hook (seize the line)
- Injecting sound from the voice node into the phone line
- Detect incoming call rings
- Decoding network messages to send to text to voice box
With these functions, the central controller can give the caller a
of options and decode which selection he/she desires. This will make
control possible of the system by phone. In this manner, the entire
can be controlled and configured using any phone in the world.
- 6/13/03 - Updated information from RC systems (still operating) and ITU Tech (defunct). The phone node has continued to function in an excellent manner. More functions have been added such as speaking the event log out loud if a user is sending commands via the phone.