The invention provides a system and method for interrogating one or more electronic labels attached to objects, the system including an interrogation device capable of radiating an electromagnetic interrogation signal which contains information in the form of a plurality of symbols, each symbol being represented by a respective time interval between consecutive dips in amplitude of the interrogation signal. The one or more of the electronic labels are capable of detecting and decoding the interrogation signal to recover the symbols, and in response to recovering the symbols generate a reply signal. The reply signal is able to be detected and decoded by the interrogation device. It is envisaged that the invention will find particular use in identifying, sorting, controlling and/or auditing objects having information bearing electronically coded labels.