Digital wave carrying restoring device

Abstract

A digital carrier restoring device relating to digital information transmission includes an A / D sampler and a digital carrier restoring phase-locking ring containing: a phase rotator, a carrier detector, a judger, a loop filter, and a digit control oscillator in which, the A / D sampler is to sample IF cross amplitude modulation signals from RF receiver to convert analog signals to digital signals, the phase rotator carrying out vector rotating to baseband signals, a digit control oscillator provides the rotating angle, the carrier detector computer the angles difference according to the signal angle difference, the loop filter filters the angle difference value signals and gets control signal of a rotating angle and the digital control oscillator accumulates the roting angle control signal to output the angle by subtracting a standard mode.

Description

technical field [0001] The invention relates to the transmission of digital information, in particular to a digital carrier recovery device. Background technique [0002] In the existing digital video broadcasting, the video signal is usually transmitted by means of quadrature amplitude modulation QAM (Quadrature Amplitude Modulation), but because the modulated signal is a baseband signal, it must be modulated into a radio frequency signal by carrier modulation to pass After the digital video broadcasting receiver receives the radio frequency signal, it must also remove the modulated carrier to extract the baseband signal, and then demodulate the baseband signal to obtain the original video transmission signal. The current carrier removal (recovery scheme) generally adopts an analog circuit or a circuit mixed with digital and analog. [0003] In the digital video broadcasting system, the quadrature amplitude modulation QAM baseband data signal must first be modulated by hig...

AI Technical Summary

Problems solved by technology

[0017] First of all, because the voltage-controlled oscillator VCO in the carrier recovery phase-locked loop is realized by an analog circuit, it has the disadvantages of difficult system design, high power consumption, and performance greatly affected by the environment.

[0018] Second, the voltage-controlled oscillator VCO outputs an analog signal that makes the fully quadrature sin(ω c t) and cos(ω c t) The signal is very difficult to obtain, mainly because the accuracy of the π / 2 analog phase-shifting network is difficult to guarantee, which in turn affects the demodulation results

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