ABSTRACT
Imperceptible transmission of speech-to-text recognized characters by means of audio watermarking is addressed for application in the standard VHF radio telephone communication. Practicability of this design is based on advances in automatic speech recognition, especially taking into account utilization of IMO Standard Marine Communication Phrases and interactive recognition process. Watermarking performances are provided by applying power preserving algorithm in critical Bark bands; OFDM like data transmission in parallel through narrowband frequency channels and error correcting encoding. Watermarking system allows embedding up to 16 five-bit characters per sec in synchronous regime under influences of intersymbol interference and additive noise of signal-to-noise ratio 15 dB. Embodiment of the design is based on standard VHF communication installation and has to provide efficiency of voice messaging by means of text visualization.
