Patent ID: 7516471

Claim:
A communication device for use in a digital television (DTV) system, comprising: a receiver that is operable to receive digital television (DTV) signals on a selected DTV channel; a transmitter operable to transmit radio communication information on a DTV channel; a base band processor coupled to the receiver and transmitter, the base band processor operable to process received DTV signals; a DTV signal detector coupled to the processor, the DTV signal detector operable to detect received DTV signals and to detect that the DTV signal is absent by the following function: F χ 2 ,2M,α,non-central (T) where T is a detection threshold, and F denotes the cumulative distribution function of a non-central chi-square (χ 2 ) random variable with 2M degrees of freedom and non-centrality parameter, α=2M (SNR) for the signal-to-noise ratio of either a pilot signal detector or a delay-multiply detector; and a controller, responsive to the DTV signal detector, to control a selection of a DTV channel to be used by the transmitter, wherein if said DTV signal detector detects that a DTV signal is absent on the selected DTV channel, the controller can direct the transmitter to transmit information on that selected DTV channel.