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US 4,232,194 AGranted
Voice encryption system
AssigneeOcean Technology, Inc.
InventorRobert H. Adams
Life of this patent
Estimating the term…
Abstract
An apparatus and method of voice encryption uses segment swapping. Features of the invention include weighting the input time-function segments by a Hamming or Hanning Window function, before converting to frequency domain segments.
Claims17
In an encoder or decoder for a voice encryption system, the combination of:
- an analog-to-digital converter for converting a first analog signal to a sequence of digital words;
- storage means for storing words from said analog-to-digital converter output in overlapping first records;
- weighting means having the overlapping digital records as an input for producing digital records in the time domain and weighted by a window function;
- first means for converting a time domain weighted record to the frequency domain producing a plurality of digital segments each representing a different frequency band;
- means for transposing segments of said digital segments;
- means for combining said transposed segments to produce a second record in the frequency domain;
- second means for converting a frequency domain digital second record to a time domain digital second record;
- accumulator means for storing time domain second records;
- and
- a digital-to-analog converter for converting said time domain second records to a second analog signal.
7 more elements
In a method of voice encryption, the steps of:
- converting a first analog signal to a sequence of digital words in the time domain;
- storing said words in overlapping records;
- processing the overlapping records by means of a data window weighting function to produce digital weighted records in the time domain;
- converting a time domain digital weighted record to the frequency domain producing a plurality of digital segments in a sequence, with each segment representing a different frequency band;
- transposing the sequence of the segments;
- combining the transposed segments to produce an encoded digital record in the frequency domain;
- converting the frequency domain encoded digital record to an encoded digital record in the time domain;
- accumulating encoded time domain digital records;
- and
- converting encoded time domain digital records to a second analog signal.
7 more elements
Dependencies are inferred from the claim text.