Multilevel data encoding and modulation technique

A multilevel data encoding and modulation system for efficient use of bandwidth in a data transmission channel, comprising:

• (a) means for separating said input bit stream sequence of binary data into odd-numbered bits and even-numbered bits based upon a bit's order in the sequence;
• (b) means for assigning a voltage level to the odd-numbered bits from a first set of voltage levels, the first set having a unique voltage level assigned to each logic level;
• (c) means for assigning a voltage level to the even-numbered bits from a second set of logic levels, the second set having a unique voltage level correlating to each logic level, wherein the second set of voltage levels is symmetrically disposed about a median logic level from the first set of voltage levels;
• and
• (d) means for combining the voltage levels assigned to the odd-numbered bits with the voltage levels assigned to the even numbered bits in order to form an aggregate bit stream, successive bits in the bit stream alternately disposed about the median voltage level;
• whereby said bit stream defines a baseband signal having a constant frequency.

A multilevel data transmission method, comprising the steps of:

• (a) creating a multilevel amplitude modulated, monofrequency baseband signal from an encoded input bit stream sequence, the period of said baseband signal having cycle-halves equivalent to one-bit interval of said bit stream sequence;
• (b) filtering said baseband signal of odd harmonics thereby creating a sinusoidal waveform;
• (c) transmitting said sinusoidal waveform to a remote destination;
• (d) remotely receiving said sinusoidal waveform;
• (e) filtering unwanted noise and harmonics from said received sinusoidal waveform;
• and
• (f) recreating said bit stream sequence from said filtered received sinusoidal waveform.