ASTRO AUDIO TONE GENERATION BY FIELD UNITS
Original Publication Date: 1997-Dec-01
Included in the Prior Art Database: 2002-Jun-12
Motorola's ASTRO technology has improved audio quality over a larger section of the coverage area than was achieved in the analog mode of oper- ation, In order to get this improvement in a digital transmission with the fewest number of bits, a vocoder has been used. The vocoders used today (both VSELP and IMBE) in ASTRO are designed for the smallest components of the human voice. As a result, audio that is not made up of the same com- ponents as the human voice, when vocoded, become distorted. Motorola customers use several audio tones as a method of communications over Radio Frequency channels. These same customers (and new ones) will want to and do use the same audio tones over ASTRO channels.