Drift Correction Modulation Scheme for Digital Audio Watermarking

The article describes a new method of embedding and extracting the digital watermark in an acoustic signal, which operates in the frequency domain and uses a drift correction modulator of the watermark´s phase angle, as well as a precise correction procedure of the watermark signal to the minimum masking threshold. This method does not require synchronization reproduction at the receiving side in order to extract the watermark. Drift Correction Modulation (DCM) is characterized by a high normalized data payload of the watermark signal and may be implemented in applications of hidden and secure data transmission. The method has confirmed its robustness against degrading factors: lossy compression, resampling, A/D and D/A conversion, noisy VHF channel. The paper presents the results of auditory tests according to the ITU-R 1116-1 standard; moreover, results of the watermark´s extraction tests in the VHF radio link, with the use of military tactical radio stations have been presented.