The influence of detector's parameters on the efficiency of radio signals with complex phase modulation receiving

Abstract

The paper presents the results of simulation of a detector, implemented on the basis of a phase locked loop device (PLL), the mathematical modeling of signals with 8-QAM modulation, and investigates the influence of PLL parameters on the receiving quality of these signals with the interference in the communication channel. As a result of the study, the optimal parameters were found to provide the maximum noise-immunity for the communication system, which uses complex types of signals phase modulation. Two methods of signal detector composition were considered and compared in terms of noise-immunity. The first one is classic detector based on PLL synchronization and the second one - modified detector with specific additional filters. Modified detector was chosen for maintaining the further experiments due to its potential higher noise-immunity. The second part of the work was dedicated to the research of detection efficiency of modified detector using complex phase modulated signal 8-QAM. The simulation of this signal and the model adequacy check were carried out using Matlab software. The next step was the research of influence of filter parameters on the modified detector's noise-immunity during the 8-QAM signal detection. The results of simulation show the optimum parameters at which the maximum noise-immunity of phase detector was achieved. These parameters may be useful for further researches or for the process of phase detector design.

Keywords

• 8-QAM
• phase detector
• PLL
• noise immunity