Voice Frequency Transmission System TUS-35 for the Transmission of Data on Telephone Lines.

A system is presented which transmits signals and messages superimposed upon the voice channel over existing telephone lines. The system is based on the frequency-shift procedure and uses the 4. 25 and 4. 5 kHz frequencies lying outside the telephony speech band. The system is fully electronic, it uses modern integrated circuits and its overall conception is highly flexible. Transmission systems ranging from one single channel linking two points to large-capacity plants comprising more than 1000 transmitting and several receiving points can be realized. Within the confines of the Swiss telecommunication network the TUS-35 system is made use of for the transmission of alarms (burglary, robbery, fire and plant supervision). This article describes the basic principles of the system and its fields of application.