STILL PICTURE TRANSMISSION DEVICE

PURPOSE:To extend the communication range by providing a transmission speed automatic changeover device applying low speed transmission at the transmission of a control signal and then transmitting a picture data at a high speed and allowing a receiver side to take sure synchronization with a sender side so as to attain high speed transmission. CONSTITUTION:A control signal being picture data information is used for SA, DA and COMMAND in a configuration of a transmission packet and the signal is sent at a low speed. Then a digital picture data is added to the information and the data is sent at a high speed. Upon the receipt of a transmission packet, a center controller 17 applies low speed transmission processing to the control signal, adds a digital picture data after the control signal and the data is sent at a high speed. That is, upon the receipt of the transmission packet, the center controller 17 receives up to the control signal at the low speed mode surely, takes synchronization with a still picture transmitter at the sender side, and receives the picture data after the control signal in the high speed transmission mode. Then a still picture transmission device 16 uses a transmission speed automatic changeover device 14 to select the low speed and the high speed transmission mode.