POTENTIAL NOISE IMMUNITY OF DIGITAL AUTO CORRELATION DEMODULATOR LANGE - MULLER

Анотація

Currently, significant attention of developers of telecommunication systems is paid to the design of modems with noise-like and noise signals. Such modems have indisputable advantages in terms of interference protection, confidentiality of information transmission, electromagnetic compatibility with neighboring electronic devices. Previously developed similar systems were focused on the use of analog elements in the equipment. The transition to the modems implementation using elements of discrete technology and digital information processing methods requires the development of new analytical methods for analyzing the noise resistance of such systems.

The paper performs a theoretical analysis of the noise resistance of the Lange-Müller demodulator, when as a carrier of binary information signal a noise process of "white" Gaussian noise type is used during transmission on a channel with constant parameters under the action of additive Gaussian noise. The results of the noise resistance analysis were performed using the method of characteristic functions, which allowed to obtain a potential theoretical estimate. In comparison with the results of previous approaches to solving this problem, the obtained results provide an opportunity to calculate the noise resistance of the digital Lange-Müller modem using the final formula, which takes into account all the physical parameters of the modem. The presented graphical dependences of demodulator noise resistance are compared with the computer simulation results. The analysis confirms their high consistency with the results of theoretical calculations.

Summing up the whole research, it is worth noting the following results: noise resistance analysis of Lange-Mueller digital modem was performed using a mathematical apparatus of characteristic functions in the presence of additive Gaussian noise; an analytical expression is found for calculating the characteristic density functions of the random variable distribution at the output of digital correlators; an expression to determine the potential noise resistance of the demodulator was obtained.