Simultaneous Transmission of Voice and Handwriting Signals: "Sketchphone System"

The "Sketchphone" is an audiographic communication terminal which makes it possible to transmit handwriting and speech signals simultaneously over a telephone channel. Computer simulation of a voice interleaving technique which causes little degradation in telephone conversation quality was carried out to achieve simultaneous transmission of two signals. A complete "Sketchphone" set has not yet been built, however. A graphic tablet, using a new pressure-conductive rubber sheet, has been developed for this Sketchphone system. Since the rubber sheet is truly pressure sensitive, false signals from the hand or fingers resting on the tablet do not occur.