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Acoustic Steganographic Transmission Algorithm,
Using Signal Coherent Averaging
Krzysztof Wodecki, Zbigniew Piotrowski, Jarosław Wojtuń
Military University of Technology, Faculty of Electronics, Warsaw, Poland,
{kwodecki, zpiotrowski, jwojtun}@wat.edu.pl
Abstract: The paper discusses the algorithm of hidden data transmission, using acoustic signal
as carrier. The perceptive transparency of hidden data was obtained with the use of psychoacoustic
model of the Human Auditory System (HAS). Spectrum differential coding of binary patterns
was used to add the hidden data to the host signal. The synchronous data decoding is enabled by
the use of signal spectrum coherent averaging procedure and drift correction procedure for frequency
and time. The diagrams present the efficiency of the algorithm both in terms of accuracy of hidden
transmission synchronization, its robustness against degradation by noise and the efficiency of hidden
data extraction.
Keywords: steganography, audio watermarking, data hiding, drift correction modulation, Human
Auditory System
I. Introduction
Steganographic systems allow for transmitting data in the host signal with
specific binary bitrate. The host signal carrying additional, hidden data, can be
the TV signal, video stream, radio music or speech transmitted by the telephone
line. One of the requirements of such systems is the imperceptibility (inaudibility or
invisibility) of hidden data within the host signal. The robustness against degrading
factors in the telecommunications chain: additive white Gaussian noise (AWGN),
resampling, lossy compression, etc. is less important than in the watermarking
systems. Also in use are acoustic steganography systems utilizing the wavelet
transform and LSB coding to hide the additional data [1][2]. LSB coding has also
been used to hide compressed data in audio signals [3]. Audio steganography
uses spread spectrum methods, which utilize statistical moments and distance
metrics [4]. Steganography also faces the issue of ensuring synchronous data
decoding. In terms of frequency, the phenomenon of signal carrier frequency
drift occurs, as well as sampling frequency drift on the receiving side [5][6][7][8].
The algorithm in question uses spectrum coherent averaging to establish the correction
factor for the undesirable angle phase drift, as well as to determine the signal