Quadrature Amplitude Modulation Demodulator for symbol timing recovery with low noise and high speed

摘要

The present invention is to provide a QAM demodulator that can perform low noise and fast symbol timing recovery operation, the present invention provides a low-noise and high-speed QAM demodulator, the modulation from the transmitting side a modulated input analog signal for this purpose digital converting means for sampling an analog to digital data of a predetermined frequency; Wherein in response to the sampling timing of analog-interpolation filter for the pulses of the interpolation operation and the sampled digital data to the digital data samples outputted from the digital conversion means in a specific desired shape and filtering means; Equalizing means for receiving the data output from the interpolation and filtering means for removing the error caused factors caused by the interference between data; Carrier recovery means for outputting to the final symbol recovery after removing the error factor caused by receiving the data output from the equalizing means to the phase offset and frequency offset; Di tekting lock means in response to a signal output from the carrier recovery means for performing a locking operation; And but do the recovered symbol timing operation for the last symbol data restoration receiving selectively input output from the data, or the carrier recovery means to be output from the interpolation and filtering means in response to the lock signal output from the lock-di tekting means, initial in operation, the symbol timing recovery operation for the last symbol data after performing the restore symbol timing operations on data outputted from the interpolation and filtering means, and the lock-di tekting in the lock-di tekting means is output from the carrier recovery means to include symbol timing recovery means for performing.