By S. Forshay, K. Gundry, and D. Robinson, C. Todd, Dolby Laboratories Inc.
PART A: A newly developed compandor provides 23 dB of CCIR weighted noise reduction in a transmission medium where starting signal-to-noise ratio is on the order of 45 dB. A two-band approach consisting of the cascade combination of sliding and fixed band compandors provides a cost effective means of maintaining excellent audio quality in stereophonic television transmission. The compandor is discussed in terms of dynamic properties including overshoot performance, sensitivity to time dispersive transmission media, and reduction of correlated noise spectra common in intercarrier television design.
PART B: The delivery to the home of program audio in digital form would have many advantages, among them the potential for very high quality and ease of encryption. Conventional high quality digital-audio conversion schemes yield high bit rates at high cost. A conversion scheme will be described which yields high quality sound, modest bit rate, low cost, and inherent resistance to bit errors.