| 摘要 |
The multilevel data encoding and modulation technique uses a pair of complementary logic sets. In its most basic form, the sets are binary sets each containing a line level for a logical one and a line level for a logical zero for a total of four logic levels. The encoding technique requires a polar change in the line level after every bit. An optional fifth level may be used in order to skew the frequency or to enable automatic gain control circuitry to ensure consistent level discrimination. The encoding technique may be used in a bipolar device, or a bias level may be applied to the signal for unipolar transmission. The encoding technique involves inverting the polarity of alternating bits, filtering out all odd harmonics, transmitting and receiving the waveform, and decoding the demodulated waveform by comparing the absolute value of the half-cycle peak-to-peak voltage gain to a predetermined table.
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