Method for improvement of G.723.1 processing time and speech quality and for reduction of bit rate in CELP vocoder and CELP vococer using the same

A method of searching an MP-MLQ (Multi Pulse Maximum Likelihood Quantization) fixed codebook through predetermination of a grid bit for predicting the positions of pulses during high bit rate decoding of voice signals in a CELP (Code Excited Linear Prediction) vocoder, which reduces process time of G.723.1, the method comprising the steps of:

• generating a target vector divided into odd order and even order pulses;
• determining an amplitude of the target vector;
• generating composite sound by using the target vector;
• comparing the composite sound with an original sound without DC;
• determining a grid bit by the comparison;
• checking whether the grid bit is zero;
• searching the even order pulses when the grid bit is zero;
• checking whether the grid bit is one (1);
• searching the odd order pulses when the grid bit is one (1);
• and
• searching all of the even and odd order pulses when the grid bit is not zero or one.