On a Slope-Quantized Ternary PCM

A new method of coding complex signals based on 3-unit (+1,0,-1) quantization of their slopes, similar to the equalslope approximation used in network synthesis, and the resultant modulation schemes have been investigated. Using some compression and equalization, the optimum SNR for sinusoidal signals is found to be 25-34 db for the PRF of 20-60 kc. When feedback is used from a local receiver to the input, the SNR is improved by 10-12 db and the dynamic range is about 25 db with acceptable SNR. With complex signals, the SNR deteriorates by about 8 db, but for narrow-band signals the quality is good even without feedback. The over-all characteristics of the systems are better than those of
\Delta-M
and
\Delta-\Sigma
modulation.