Military Communications and Information Technology: A Trusted ...

Chapter 4: Information Assurance & Cyber Defence
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The final test was the verification of extraction efficiency after prior addition
of white Gaussian noise with specific power to the assayed signal. Fig. 11 presents
the signature extraction efficiency results in the function of the assayed signal power
to noise power ratio. With the reduction of the noise power (increase of the SNR
factor value) added to the signal, the signature extraction efficiency increases.
Figure 11. Signature extraction efficiency results in the function of the assayed signal power
to noise power ratio
IV. Conclusions
The article discusses the algorithm for creating a hidden transmission channel
in audio signals. Depending on the selected variant, the achievable bitrates are
43 bps to 172 bps. Also discussed was the angle phase correction algorithm, based
on coherent averaging, and time synchronization mechanism. The experimental
results are satisfactory. Further studies of the subject should focus on implementing
the detecting-corrective embedding module and performing a number of experiments
on the extraction efficiency during signal transmission in various telecommunications
links (VoIP, VHF).
Acknowledgment
This paper has been financed from science funds granted within the years 2010-
2012 as a research project of the Polish National Centre for Research and Development
No. 0181/R/T00/2010/12.