Investigation of methods of evaluating quality of transmitted signal in communication channel

There are many different measurement methods and methods, thanks to which digital models of the system are analyzed for noise immunity, distortion, security, versatility, cost-effectiveness and accuracy. The concept of “universality” is general in nature and applied to any digital signal, the concept of “cost-effectiveness” is the efficient use of bandwidth, equipment and network resources. “Accuracy” is the key requirement in the construction and transmission of information over a communication network. Various characteristics of the transmission channel - bandwidth, transmission levels, dynamic range, level diagram, amplitude- frequency response, phase-frequency response, the error rate for a certain time interval give an idea of the state of the channel, path, and equipment. According to their analysis, it is easy to eliminate or improve that component of the communication channel. The article presents and investigates popular tools for assessing the quality of transmitted information over a digital communication channel. The MATLAB Simulink software environment was used, a digital communication channel was modeled using QPSK modulation. The MATLAB Simulink software environment was used, a digital communication channel was modeled using QPSK modulation. This modulation is actively used in satellite broadcasting, when streaming satellite channels SD and some HD channels, works at high transmission speeds, thereby being one of their most popular at the moment. An experiment of signal transmission over a communication channel was carried out; the received signal was evaluated in various ways for noise immunity and distortion.