FIELD: technology for creating artificial interference to mask acoustic and electromagnetic channels for leaking speech information.
SUBSTANCE: in accordance to the invention, a masking signal should be generated, which simultaneously masks analog signal and speech signal in digital form. Speech-like signal is created on basis of original signal being masked by means of modulation of zero intersection moments of masked signal by a noise signal. To modulate zero intersection moments of speech signal, the speech signal is clipped, and then resulting clipped signal is integrated, transforming it to saw-tooth signal, resulting saw-tooth signal is summed with noise signal, and after that resulting total signal is clipped. To increase masking effect (to exclude pauses, connected to pauses in speech being masked) resulting noise-like signal is summed with second speech-like signal, to generate which noise signal is clipped (which does not have pauses), and then zero intersection points of clipped noise signal are modulated with speech signal. To mask speech signal in digital form, resulting speech masking signal is added to an identical signal converted to digital form.
EFFECT: increased masking effect of speech-like noise signal.
2 cl, 3 dwg
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Authors
Dates
2007-11-10—Published
2005-10-11—Filed