Patent
Voice privacy system
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TLDR
In this paper, a selected bandwidth of speech frequencies is divided into a plurality of sub-bands and each sub-band is processed in a "Weaver modulator" type of circuit for filtering, frequency translation, and inversion.Abstract:
A selected bandwidth of speech frequencies is divided into a plurality of sub-bands and each sub-band is processed in a "Weaver modulator" type of circuit for filtering, frequency translation, and inversion. The sub-bands which have undergone frequency translation are then combined to provide a scrambled output which is transmitted to a receiver where the converse processing of the scrambled signals including filtering, frequency translation, and inversion is accomplished to produce the original speech modulated input.read more
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Vestigial sideband generator particularly for digital television
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TL;DR: In this paper, a voice band splitting scrambler is described, which consists of a band splitting unit for splitting an input voice signal into a plurality of band channels, and a scrambled voice signal generating unit for carrying out spectrum-inverting and band-relocating operations on the respective channels to generate a scrambled signal.
PatentDOI
Method and apparatus for distorting a speech signal
TL;DR: In this paper, a speech signal is divided into a plurality of sub-bands by filtering, and the subbands are individually sampled at a sampling frequencing which is at least double that of the sub-band bandwidth.
References
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Patent
Transmission control in signaling systems
TL;DR: In this article, a two-way signal transmission system employing a variable or noisy transmission medium, such as the radio link in a 2-way radio telephone system, is described.