| 摘要 |
The specification discloses a system for scrambling digital signals transmitted between a synchronous data transmitting station and a receiving station. When the scrambling system is used with a facsimile system, a first scrambler is connected between the video amplifier and the transmitter modulator of the transmitting facsimile station. The first scrambler includes digital circuitry for digitizing the output of the video amplifier and enciphering circuitry for enciphering the digitized output of the video amplifier and for transmitting the enciphered output to the receiving facsimile station. A second scrambler is connected between the demodulator and the write amplifier of the receiving facsimile station. The second scrambler includes deciphering circuitry for deciphering the output of the demodulator and for applying the deciphered output to the write amplifier to provide a duplicate of the transmitted facsimile material. Initialization between the first and second scrambler is accomplished with the use of correlation and prime patterns. Circuitry is provided to maintain the first and second scramblers in synchronization with one another, and alarm systems are provided to indicate malfunction of the scramblers and to prevent the transmission of sensitive data in the unciphered state. |
