AGC CIRCUIT FOR A DIGITAL RECEIVER.

摘要

An AGC circuit for a digital receiver that receives a digital television signal or the like, including a pilot, and formatted in a plurality of repetitive data segments, each data segment comprising a fixed number of multilevel symbols occurring at a constant symbol rate. The multilevel symbols are converted to corresponding digital values and the pilot (represented by a DC offset) is removed from the digital values. Every fourth symbol is sampled and the samples are accumulated and divided to derive an average symbol value. The average symbol value is compared with a reference average symbol value and the result of the comparison is an AGC potential that controls the tuner and IF gains. A cable/terrestrial input alters the sampling for cable signals to compensate for high level sweep testing in cable systems.