16QAM (Quadrature Amplitude Modulation) carrier synchronization and loop synchronization locking detection method

Abstract

The invention provides a 16QAM (Quadrature Amplitude Modulation) carrier synchronization and loop synchronization locking detection method. Through utilization of the method, the influence of signal amplitude on 16QAM carrier synchronization and loop synchronization locking detection can be clearly eliminated. The technical scheme provided by the invention is realized through the following processthat carrier synchronized data is divided into I and Q ways; high frequency components in the data are filtered through lowpass filters; the filtered data is sent to a carrier synchronization lockingdetector for carrier synchronization locking detection; the carrier synchronization locking detector compares normalized high order moment calculation values of the I and Q ways with a detection threshold at each moment and judges whether a carrier synchronization loop is locked or unlocked; an indicator drives an FPGA reset signal to reset a phase-locked loop of the carrier synchronization loop;digital intermediate frequency signal carriers are demodulated to a zero intermediate frequency module through I and Q demodulators, so the carrier synchronization loop is locked on an accurate frequency again; zero intermediate frequency signals are sent to a rear-end clock recovery loop module for clock recovery; and judgment is carried out by a judgment module, thereby acquiring a receiving sequence.

Description

technical field [0001] The invention relates to digital demodulation of 16-order quadrature amplitude modulation (quadrature amplitude modulation), which is widely used in medium and large-capacity digital microwave communication systems, high data transmission of cable TV networks, satellite communications and other wireless communication fields, and is used to detect digital The method of whether the carrier demodulation loop in the demodulator is locked. More specifically, the present invention relates to a quadrature amplitude modulation 16QAM carrier synchronization loop synchronization lock detection method. technical background [0002] In a digital communication system, in order to transfer the signal to a frequency suitable for long-distance transmission, it is necessary to move the spectrum of the baseband signal to the radio frequency at the transmitter. Correspondingly, at the receiving end, the signal needs to be moved back from the radio frequency to the baseb...

AI Technical Summary

Problems solved by technology

At the same time, it should be noted that one of the biggest shortcomings of this type of determination method is that the lock indication threshold is related to the input amplitude of the signal.

When the front-end AGC performance or input signal level is unstable, it is easy to cause false lock or alarm

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