REDUCED COMPLEXITY SIGNAL TRANSMISSION SYSTEM

摘要

In a CELP coder a comparison between a target signal and a plurality of synthetic signals is made. The synthetic signal is derived by filtering a plurality of excitation sequences from a one-dimensional codeboo k by a synthesis filter having parameters derived from the target signal. The excitation signal which results in a minimum error between the target signal and the synthetic signal is selected. The search for the best excitation signal requires a substantial computational complexity. To reduce the complexity a preselection of a small number of excitation sequences is made by selecting only every L th codebook entry for preselecting a plurality of excitation sequences. With this small number of excitation sequences a full complexity search is made in whi ch all excitation sequences surrounding the preselected ones are involved in the selection.