| 摘要 |
<p>The application is to a telephone and digital data transmission link between an exchange (ZSt) and a data and telephone terminal or receiver (TS1). Connection is by four cores, two (a1,b1) for telephone and two (c1,d1) for data. The terminal receives digital pulses by voltage modulation and transmits by current modulation, the two transmissions being interleaved. In order to keep the terminal oscillator (Osz2) synchronised with that (Osz1) of the exchange use is made of the pulses coming into the terminal. Each rising, or positive going, edge is used as a synchronising mark. As these occur very frequently in a data block the terminal synchronisation is sufficiently accurate to govern its transmissions. It enables the use of a less costly oscillator at the terminal than at the exchange.</p> |
