| 摘要 |
For a better use of the transmission channels, a higher-order codification was adopted. In that regard, the amplitude shift keying (ASK), the frequency-shift keying (PSK), the phase shift keying, as well as a combination of ASK and PSK, the so-called quadrature amplitude modulation (QAM), are already known. According to the invention, various pulse times are provided for a high-order codification. The pulse times are represented with periods and half periods of a frequency alternating current. The continuous pulses are transmitted in one non stop sequence. Such a codification is not susceptible to faults. The hardware is very simple. The synchronization requires only an identification symbol, for instance a start-of-transmission sign. Counting the periods and half-periods is a safe way for ensuring synchronization, since the pulse times are marked in the sequence with an amplitude change. If the quadrature amplitude modulation is considered for coding alternating currents, the steps can be multiplied. Various amplitude steps may also be foreseen. A duplex transmission also appears to be possible on the basis of QAM. |
