Hilbert-Huang Transform Based Instantaneous Frequency Features for Underwater Voice (I) Transmission

This paper examines the features of a Hilbert-Huang transform instantaneous frequency for application in underwater voice (I) transmissions. The duration and sampling frequency of the voice (I) sample were 5 s, and 8000 Hz, respectively. The voice (I) sample was inputted into a Matlab-based direct mapping orthogonal variable spreading factor/orthogonal frequency division modulation underwater multimedia communication platform. An underwater actual test channel model was employed in the proposed Matlab-based platform. Applying Hilbert-Huang time-frequency analysis to investigate the IF features of the received voice (I) signal resulted in transmission bit error rates of 0, 10(-4), 10(-3), 10(-2) and 10(-1). The mean frequencies of the voice sample (I) signal for IF2 were 646.6, 644, 648.3, 625.2, and 669.0 Hz, respectively, for the transmission bit error rates of 0, 10(-4), 10(-3), 10(-2) and 10(-1). The mean frequencies of the voice sample (I) signal for IF2 were 2.6, -3.7, 21.1 and 22.4 Hz, respectively, for the transmission bit error rates of 10(-4), 10(-3), 10(-2) and 10(-1).