Patent ID: RE38876

Claim:
In combination for operating upon analog signals transmitted through a coaxial cable providing quadrature amplitude modulated data to recover the quadrature amplitude modulated data from noise and distortions in the coaxial cable, first means for converting the analog signals to analog signals having a particular intermediate frequency, second means for converting the analog signals at the particular intermediate frequency to corresponding digital signals, third means for operating upon the digital signals to provide the digital signals with a quadrature phase relationship, fourth means for passing the low frequency components in the digital signals with the quadrature phase relationship, fifth means for derotating the digital signals passed by the fourth means, sixth means responsive to the derotated digital signals for recovering, in digital form, the quadrature amplitude modulated data, the fifth means including seventh means for multiplying the output from the fourth means by trigonometric signals in a quadrature phase relationship to provide for a recovery in digital form of the quadrature amplitude modulated data from the noise and distortions in the coaxial cable, eighth means responsive to the derotated digital signals for producing error signals, and ninth means responsive to the error signals from the eighth means for regulating the analog signals from the first means at the particular intermediate frequency.