A method and apparatus for power conservation is provided for a multi-mode wireless communication device (100) capable of operating in a plurality of networks, each of the plurality of networks having a network signal with predetermined spectral characteristics. The wireless communication device (100) includes a variable bandwidth signal detector (140), a threshold detector (145), and a controller (120). The variable bandwidth signal detector (140) receives radio frequency (RF) signals and defines a detection bandwidth for signal detection. The threshold detector (145) is coupled to the variable bandwidth signal detector (140) and detects a network signal within the RF signals in response to determining whether a signal is present within the detection bandwidth having a signal strength greater than a predetermined signal strength. The controller (120) is coupled to the variable bandwidth signal detector (140) and the threshold detector (145) and offsets a center of the detection bandwidth of the variable bandwidth signal detector (140) in response to the predetermined spectral characteristics of the network signal.