| 摘要 |
<p>The coded data are transmitted from a transmitting station (S) to a receiving station (R) via a communications channel (3), which may be a landline, radio link or optical fibre. The data generator (1), e.g. a teleprinter, is fed to a mixet circuit (4), where it is coded by the output of a pulse code generator (6), linked to a variable key generator (8). Before each transmission, the variable key signal is transmitted directly via a switch (9). At the receiving station, the incoming key signal is compared (12) with the output of an identical key generator (11), until the two signals are identical, but inverted and synchronised. At this point, the coded data is switched (10) to a pulse code generator (7) which decodes the original data and feeds it to the receiving machine (2).</p> |
