Clock synchronization method for quadrature amplitude keyed signal demodulators

The purpose of the research is to develop a method for restoring clock synchronization for signals demodulators with square amplitude manipulation.
Methods are based on the foundations of quasi -optimal receipt of multi -position signals, the theory of constructing radio -receiving systems of digital communication lines, methods of mathematical modeling of signals, probability theory and mathematical statistics. The well -known algorithms for assessing the phase of clusion of clusion in the presence of manipulation interference, due to a multi -level signal modulation, were used. The assumption was assumed that the channel satisfies the conditions of Naquvist, and the distorting hindrance signal is an additive white Gaussian noise.
Results. The development of a method for restoring clock synchronization is implemented, which consists in using solutions and reducing each pair of adjacent symbols to a binary signal by centering them relative to the zero point and weighting by level. Analytical dependences of the phase estimate for the clock synchronization device are presented, as well as structural and functional diagrams of the implementation of various options for constructing this device as part of demodulators of multi-position signals with quadrature-amplitude manipulation. The obtained graphs of the components of the fluctuation characteristic of the discriminator of the clock synchronization device indicate that the developed algorithm allows resolving the contradiction between the reduction of the manipulation component and the growth of the noise component of the fluctuation characteristic.
Conclusion. From the point of view of the noise immunity of the optimal, coherent demodulation of signals is, however, a clock (phase) synchronization of the reference generator of the demodulator with the received signal, namely ensuring the coincidence of clock impulses in the decisive device with the ends of the end of information symbols. The use of the developed method, as shown by the results of theoretical and experimental studies, allowed about 0.5 to 0.7 dB to increase the noise resistance of the demodulator of radio -receiver systems of digital communication lines.

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