Three-level delta modulation for laplacian source coding

This paper proposes a novel solution for coding of time varying signals with Laplacian distribution, which is based on delta modulation and three-level quantization. It upgrades the conventional scheme by introducing the quantizer with variable length code. Forward adaptive scheme is used, where the adaptation to the signal variance is performed on frame-by-frame basis. We employ configurations with simple fixed first-order predictor and switched first-order predictor utilizing correlation. Furthermore, we propose different methods for optimizing predictor coefficients. The configurations are tested on speech signal and compared to an adaptive two-level and four-level delta modulation, showing that proposed three-level delta modulation offers performance comparable to a four-level baseline with significant savings in bit rate.