| 摘要 |
In the transmission of information, particularly long-distance speech signals, between a first and a second station, the information is transmitted from the first to the second station by means of a code alternating current of predetermined frequency and phase-state, and from the second station to the first station by means of a code alternating current which has the predetermined frequency and a phase shifted by 90 DEG with respect to the predetermined phase. The phase of the code alternating current transmitted from the second to the first station can be driven by means of the phase of the code alternating current transmitted from the first to the second station. The code alternating currents may contain code elements in the form of half waves or periods of differentiated amplitudes of the code alternating current, which is essentially sinusoidal. In order to use multiplication, two code-alternating-currents, whose phases are shifted by 90 DEG will respect to each other, can be combined into one sum alternating current of the resulting phase, and to this sum alternating current at least one further code alternating current can be added, whose phase is shifted by 90 DEG with respect to the resulting phase of the sum alternating current. The addition of further code alternating currents can be repeated, as long as the error-frequency during demodulation at the receiving end remains sufficiently low.
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