Patent ID: 7929649

Claim:
A method of characterizing a communication signal carrier transmitted on a communication channel in a digital cable communication receiver, comprising: setting a bandwidth of the communication channel to a plurality of different bandwidth values; for each of the bandwidth values, obtaining information indicative of a corresponding signal level present in the communication channel when set to that bandwidth, the signal level information including a plurality of digital values respectively associated with the plurality of bandwidth values; using the signal level information associated with the plurality of bandwidth values to determine whether the communication signal carrier is a digital carrier, wherein using the signal level information associated with the plurality of bandwidth values to determine whether the communication signal carrier is a digital carrier includes determining a sum of the digital values; setting the bandwidth of the communication channel to a further plurality of different bandwidth values which each differ from said plurality of bandwidth values, said signal level information including a further plurality of digital values respectively associated with said further plurality of bandwidth values; and determining a further sum of said further digital values.