Systems, methods, and apparatuses for detecting digital television (dtv) communications signals

Abstract

A received RF signal is down-converted to a baseband or low-IF digitized signal in order to search for a pilot signal that indicates a presence of a DTV signal such as an ATSC DTV signal. The pilot signal characteristically resides in a fixed frequency range for all valid DTV signals and is extracted by processing the baseband or low-IF signal in multiple stages. The first stage reduces signal information to that pertaining to the frequency band covering all valid pilot frequencies, thereby reducing the sampling rate and computational complexity of subsequent operations. A second stage operates on this reduced rate signal to focus on a series of particular pilot frequencies for interrogation. For each such candidate frequency, the cyclostationarity of the signal is measured and tested for statistical significance relative to the background energy to yield an effective test that is invariant with respect to background noise level.