A method of discriminating between a first type of article surveillance marker and a second type of article surveillance marker, the method comprising the steps of: receiving signals that are present in said article surveillance interrogation zone at respective times over a predetermined period of time; forming a sequence of samples corresponding to said signals received during said predetermined period of time; analyzing each sample of a first group of samples to detect whether each sample of said first group is indicative of said signature characteristic of said first type of marker, said first group of samples consisting of at least some of said sequence of samples and simultaneously analyzing each sample of a second group of samples to detect whether each sample of said second group is indicative of said signature characteristic of said second type of marker, said second group of samples consisting of at least some of said sequence of samples; and actuating an alarm if at least a first predetermined number of said samples of said second group of samples is detected as being-indicative of said signature characteristic of said second type of marker, unless at least a second predetermined number of samples of said first group of samples is detected as being indicative of said signature characteristic of said first type of marker. <IMAGE>
Method and apparatus for detecting an eas marker using a neural network processing device