Simultaneous transmitter for voice and pictures and writings

Abstract

Abstract PURPOSE:To keep the quality of voice, by narrowering the pass band of audio signals at the pictures and writings mode and widening the pass band at pictures and writings mode, through the provision of a band selecting switch, in the voice and pictures and writings simultaneous transmission using a line having a narrow tramsmission frequency band such as a telephone line. CONSTITUTION:In transmitting sound and pictures and writings at the same time, a pictures and writings mode signal Z changes over switches 3, 3' to the position of a narrow pass band filter 5 via a picture and writings mode detection circuit 14, and an audio signal passes through a microphone 1, an amplifier 2 and the switch 3, the band is limited at a narrow band pass filter (0.3-2.7kHz) 5, and the signal is transmitted through communication lines 8, 9 via the switch 3' and an output transformer 7. Longitudinal axis signals x, y and the pictures and writings mode signal Z of a document signal are introduced to a pictures and writings signal conversion circuit 13 and transmitted as a voice band (2.9- 3.4kHz) signal. When no document mode signal exists, the circuit 14 changes over the switches 3, 3' to a broad band (0.3-3.4kHz) filter 6 to transmit voice in broad band.

Inventors

• 👤 Kiyoshi Obara
• 👤 小原　清

Bibliographic Details