An apparatus, a cognitive radio, a processor, a method, and a machine-readable medium for detecting a presence of a signal in a communication channel are disclosed. An apparatus includes a processor configured to select one or more peak samples of two or more fields of a sampled signal and configured to determine one or more absolute values of the one or more peak samples of the two or more fields. In addition, the processor is configured to superimpose the one or more absolute values of the one or more peak samples of the two or more fields. The processor is further configured to combine the one or more absolute values that fall within a predetermined window to produce a peak value and configured to compare the peak value with a threshold to determine a presence of a signal in the communication channel.