| 摘要 |
PURPOSE:To transmit a signal on a narrow band line in a high speed, by coding a half wave or full wave element limited at zero cross point of a sinusoidal carrier and transmitting the coded pulse by varying the amplitude. CONSTITUTION:A modulation circuit 1 consists of a sinusoidal wave carrier oscillator 7, monostable elements 8, 9 and switching elements 12, 13, and the coded output of a picture/ternary converter 3 corresponds to a half wave or a full wave limited with the zero cross of the carrier. An output of the converter 3 becomes a pulse train where the amplitude is varied corresponding to the ternary coded pulse. A signal transmitted via a telephone line 5 is applied to Schmitt trigger circuits 19-21 of the demodulation circuit 2 and a monostable element 22. Each Schmitt trigger circuit processes the tri-state pulse, the original signal is demodulated with an output of a delay circuit 24 and an inhibit circuit 28 and applied to a reproducer 6. |
