Adaptive expansion table in a digital telephone receiver

Abstract

A digital telephone (60) comprises send equipment (40) and receive equipment (50), coupled via a signal splitter/combiner (61) onto a digital telephone line (62) for communication with a remote party (90). The send equipment (40) comprises an A-law map (12) and a mu-law map (43). Receive equipment (50) comprises an inverse A-law map (14) and an inverse mu-law map (52). Maps (12,43) are selectable by the user (80). Similarly, inverse maps (14,52) are also selectable by the user (80). Receive equipment (50) may further comprise an un-quick-fix module (55) for removing unwanted insertions of quick fixes (25) inserted into the telephone line (62) by international telephone companies. Receive equipment (50) may further comprise a digital signal processor (57), computer (56), a set of pre-stored templates (58) corresponding to possible incoming telephone characteristics, and a caller parameter decipher module (51). In a preferred embodiment of a digital telephone receiver (50), an adaptive expansion table (95) is used to expand the digital signal at the receiver (50) from a relatively coarse resolution to relatively fine resolution. The configuration of the adaptive expansion table (95) is commanded by a control computer (99). Computer (99) is responsive either to a human control operator (80) or to statistics gathered by a statistics gathering module (97). The set of statistics to be gathered by the module (97) can be established by configuring a set of voice and data parameters (98).