GPS Synchronization of Audio Watermarks in the Maritime Automatically Identified Radiotelephony

Audio watermarking (AW) technology in cooperation with GPS synchronization of watermarked frames is proposed for application in the maritime VHF communication for automatic identification of radiotelephone messages. Automatic identification ensures efficient messaging from the very beginning of a radio transmission, while eliminating the human factor inherent in voice identification. AW refers to inaudible embedding of additional data just into the post microphone signal, using standard marine installations without any additional radio channel resources. The designed algorithm is based on data embedding in the Fast Fourier Transform domain with the rate of 32 bit/s. The experimental prototype of the device is designed on the base of micro-controller development kit 32F429IDISCOVERY and GPS module NEO-6M-0-001. Designed system, applied for automatic ship’s identification, provides the full compatibility with the existing radio installation, and does not require replacement of standard VHF transceivers and operational procedures. Besides automatic identification the system may be used in the special applications, for example, by the threat of terrorist attack; generally contributes to navigation safety and information security.