| 摘要 |
PURPOSE:To decrease the scale of circuit, by directly converting an audio frequency signal into digitized information burst signal and the digitized information burst signal into the audio frequency signal. CONSTITUTION:An audio frequency signal from a transmitter 21 is digitized at a converter 23 and converted into burst shape information burst signal. On the other hand, a service signal from a signal generator 25 is converted into a control bit signal at a coder 27 and given to a code multiplexer 31 together with an information burst signal. A code multiplexer 31 sums up the information burst signal, control bit signal and synchronizing bit signal, and the result is converted into a code burst signal and transmitted to a subscriber line 15 as a transmission line burst signal of bipolar via a 4-2 line converter 33. At reception, the reverse route is followed, and the code burst signal is converted into the audio frequency signal via the information burst signal. |
