Synchronization method of download ripple and symbol timing under low signal-to-noise ratio

Abstract

The invention belongs to the technical field of digital communication, and in particular relates to a carrier and symbol timing synchronization method. Under the condition of low signal-to-noise ratio, the method for synchronizing the wave and symbol timing includes: the receiving end generates two baseband signals through quadrature demodulation of the received signal, and uses the numerical control oscillator of the symbol timing loop to synchronize to obtain the pilot phase and fractional time Delay, use the pilot phase to detect the phase of the baseband signal, extract the carrier phase, complete the carrier synchronization, use the fractional delay to perform fractional interpolation to obtain the two-channel symbol information, recover the phase ambiguity of the two-channel symbol information, and convert the two-channel symbol information. The information is converted into an output signal. The invention combines the two realization loops of carrier synchronization and symbol timing synchronization, realizes carrier synchronization by using the pilot frequency information skillfully extracted by the symbol timing loop, solves the problem of phase ambiguity at the same time, and reduces the complexity and realization of demodulation. error.

Description

Technical field[0001]The present invention belongs to the field of digital communication, and more particularly to a carrier and symbol timing synchronization method.Background technique[0002]In a digital communication system, synchronization is an essential link, which is mainly to restore the original information bit from the received signal, and use these parameters to achieve the desired purpose.[0003]Since the transmitting end carrier in the digital communication system is not exactly the same as the receiving end, the center frequency of the transmitted signal is deviated from the zero point, resulting in a frequency offset problem in the receiving end signal during the transmission signal. The phase of the channel transmitted signal will also cause phase jitter due to the influence of the Doppler effect. The carrier frequency is exposed to the rotation of the symbol point on the constellation. It will adversely affect the performance of the demodulation; the carrier is relati...

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Problems solved by technology

[0006] The present invention aims at using the method of pilot frequency insertion to realize carrier and symbol timing recovery, but the carrier synchronization convergence is unstable and there are large fluctuations, which affects the technical problem of demodulation performance, and the purpose is to provide a download wave and symbol timing under the condition of low signal-to-noise ratio synchronization method

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