In one implementation, a receiver has a module to detect a carrier within a portion of a digital representation of a received signal. In addition, the receiver includes a module to calculate the cross-correlation between the portion of the digital representation of the received signal and a reference signal representing an expected pulse pattern. The receiver also has a module to generate an estimate of a portion of a message potentially included in the digital representation of the received signal. The receiver further includes a screening module to generate a feature vector representing the estimated message, project the feature vector into a feature space, and determine the likelihood that the digital representation of the received signal includes a message. If the digital representation of the received signal likely includes a message, the receiver includes a non-coherent matched filter to recover the message from the digital representation of the received signal.