Comparative study of 24 kb/s ADPCM algorithms

Abstract

The paper is devoted to comparison of four algorithms of 24 kb/s ADPCM, standard ADPCM (ADPCM-1), and three new modified algorithms (ADPCM-2, ADPCM-3, ADPCM-4). The purpose of the modified algorithms is to reduce the nonlinear distortion introduced by ADPCM when high data rate signal passes through it. The performances of the four algorithms are researched using QAM signal at data rate of 9.6kb/s. The simulation results show that the performance of ADPCM-4 is better than that of ADPCM-3, and the performance of ADPCM-3 is better than that of ADPCM-2, and the performance of ADPCM-2 is better than that of ADPCM-1.

Comparison Between 40kb/s ADPCM Algorithms

“…The design of QAM constellations has strong impact on reducing ADPCM distortion [11]. Four constellations are considered, rectangular, (5,11), (4,12), (8,8) circular as shown in Figure 2.…”

“…Two ways were suggested to overcome this issue. The first way is to modify the ADPCM algorithm [6][7][8][9], while, the second way suggested to modify the data transmission model [10][11][12].…”