Open AccessTime and phase synchronization in communication system with a digital pseudo-random modulation
Author(s) -
Dmitry Sergeevich Kokin,
O. G. Ponomarev
Publication year - 2020
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/1679/2/022018
Subject(s) - computer science , synchronization (alternating current) , modulation (music) , communications system , additive white gaussian noise , asynchronous communication , signal (programming language) , electronic engineering , white noise , algorithm , telecommunications , channel (broadcasting) , engineering , programming language , philosophy , aesthetics
The paper is concerned a model of a digital communication system where the samples of white Gaussian noise with zero mean and dispersion σ 2 are used as a modulated (carrier) low-frequency signal. Methods of the digital-phase modulation are used in a system for transmission of information message. The communication technology reminds CDMA (Code Division Multiple Access). However, a key of feature of this system is that digital samples of white Gaussian noise are used to increase the spectrum of the information message instead of traditional Walsh-Hadamard binary sequences. In this system the repeat period of the pseudo-random sequence values is specified by the parameter and can be equal to the time (duration) of several information symbols contrast to CDMA, in which the duration of repetition period equals to the duration of modulating symbol. On the one hand, the solution allows you to increase the confidentiality of the transmitted message and more evenly expand its frequency spectrum as compared with the existing of CDMA methods. On the other hand, scientists face two significant scientific tasks that make the work meaningful. First, it is necessary to ensure the synchronous operation of pseudo-random sequence generators in the receiving and transmitting devices. Secondly, it is necessary to define a phase shift amount of the frequency-change oscillator in receiving device. Both problems are the result of the asynchronous starting of the receiver. A control signal is used to solve these problems in the radio communication system which is transmitted simultaneously with an information message. So the result of modulator work is the sum of both information and control modulated signals. The proposed methods and algorithms provide the coherent signal processing with the digital pseudorandom modulation in the receive path of communication channel. The paper is a course of early research studies and it contains a detailed mathematical description of modulation and demodulation signals in the communication system with the digital pseudorandom modulation. The numerical model of the system is described in MatLab language. All numerical experiments were carryout in a mathematical computing system of MatLab.