| 摘要 |
A full duplex data communications system using a single transmission circuit is shown. Each terminal of the system has its receiver circuit provided with a digital filter to remove from its input circuit, the frequencies being used for data transmission at that terminal. The digital filter is switchable by the data signal to be transmitted and will be set to block from the receiver, the particular frequencies then being used to transmit data. In the preferred embodiment, the signal on the transmission line is converted to a delta modulated signal which is combined with its prior signal delayed by an interval dependent upon the data being transmitted from that terminal to generate a delta modulated filtered signal carrying the received data. The filtered signal is then converted to recover the received data.
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