| 摘要 |
The output of a digital encoder is delivered to a digital data scrambler prior to being encoded as a multilevel (e.g., quaternary) signal for transmission. The digital input to the scrambler is operated on in a deterministically randomized manner which results in a digital output that is modified so as to insure the virtual elimination of unwanted DC shift in the multilevel signal. At the receiving end of the transmission facility, the inverse operation, again deterministic, returns the received digital signal to its original form prior to the decoding operation. In the preferred embodiment, the scrambler (and descrambler) comprises a one-cell feedback shift register with a modulo-2 adder in the feedback coupling. |
