| 摘要 |
PURPOSE:To facilitate return to normal procedure in case of the occurrence of an error in the transmission of a control code by performing mutual communication between facsimile terminals by detecting a modulation speed from a received signal and by performing transmission control at a corresponding speed. CONSTITUTION:During the reception of a facsimile terminal, a signal inputted from an input terminal 11 is corrected with regard to circuit level variations and then inputted to a demodulating circuit 10 to output code information to a control circuit 14 through normal modem operation. When a modem having two different modulation speeds is used, the output of an automatic gain control circuit 12 is passed through a squaring circuit 15 and timing extraction filter circuits 16a and 16b to regenerate the clock of the modulation speed of the received input signal, and it is inputted to a logical circuit 17, so that only a clock coincident with the modulation speed of the received signal is used for demodulating operation. When the modulation speeds are equal and transmission speeds are different, the speed of the received data is detected from the amplitude level of a base band signal. |
