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US 4,058,677 AGranted
Sound scrambling equipment
AssigneeLear Siegler, Inc.
InventorsPeter Maitland, William H. Draeger
Life of this patent
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AssigneeLear Siegler, Inc.
InventorsPeter Maitland, William H. Draeger
Estimating the term…
Intelligence, such as voice signals, is scrambled for secrecy communication by translating the frequency spectrum of the intelligence by mixing the signals within the frequency spectrum with a local oscillator signal having a frequency that varies between a plurality of discrete frequencies at a selected rate. The translated spectrum is split into two or more channels, and the scrambled intelligence having a frequency spectrum above a selected value is passed through a first channel wherein the frequency spectrum of the signals is reduced to a frequency spectrum at the lower end of the spectrum of the unscrambled intelligence that is not being used by the translated intelligence. The entire frequency spectrum of the translated intelligence is passed through a second channel and the output of each channel is combined and the bandwidth thereof is limited to a selected bandwidth. In a complete communication system the scrambled intelligence is unscrambled by translating the frequency spectrum of the scrambled intelligence by mixing the signals within the frequency spectrum of the scrambled intelligence with a local oscillator signal having frequencies that vary between a plurality of discrete frequencies at a selected rate in synchronism with the local oscillator signal of the scrambler unit. The translated scrambled input is passed through two or more channels with the signals above a selected frequency level being passed through a first channel wherein the frequency spectrum of the scrambled intelligence is reduced to the frequency spectrum at the lower end of the frequency spectrum of the unscrambled intelligence that is not being used by the translated intelligence and the outputs of the channels are combined as clear intelligence and bandwidth limited.
A method of scrambling intelligence within a known frequency spectrum comprising the steps of translating the frequency spectrum of the intelligence by mixing the signals within the known frequency spectrum with a local oscillator signal having a frequency that varies between a plurality of discrete frequencies within a selected band at a selected rate, passing only that portion of the translated frequency spectrum above a selected frequency through a first channel, translating the passed portion to a frequency spectrum at the lower end of the frequency spectrum of the unscrambled intelligence that is not being used by the intelligence translated by the local oscillator signal, passing through a second channel the entire frequency spectrum of the intelligence translated by the local oscillator signal, combining the output of each channel, and limiting the bandwidth of the combined signals to a selected bandwidth.
A voice secrecy system comprising a first local oscillator signal source having a frequency that varies between a plurality of discrete frequencies at a selected rate, a mixer having a voice signal input coupled to a source of voice signals to be scrambled and a local oscillator signal input coupled to the first local oscillator source, a first channel for passing the lower sideband of the mixed signals, a second channel, means in the second channel for limiting the signal passed through the second channel to only the portion of the lower sideband above a selected frequency, means in the second channel for translating downward the frequency spectrum of the portion of the lower sideband in the second channel to a frequency spectrum below the lowest frequency of the lower sideband, means for combining the lower sideband passed through the first channel and the portion of the lower sideband passed through the second channel, and means for limiting the bandwidth of the combined signal to a selected bandwidth.
A voice secrecy system comprising a scrambling unit and an unscrambling unit, the scrambling unit comprising a first local oscillator signal source having a frequency that varies between a plurality of discrete frequencies at a selected rate, a mixer having a voice signal input coupled to a source of voice signals to be scrambled and a local oscillator signal input coupled to the first local oscillator source, a first channel for passing the lower sideband of the mixed signals, a second channel, means in the second channel for limiting the signal passed through the second channel to only the portion of the lower sideband above a selected frequency, means in the second channel for translating downward the frequency spectrum of the portion of the lower sideband in the second channel to a frequency spectrum below the lowest frequency of the lower sideband, means for combining the lower sideband passed through the first channel and the portion of the lower sideband passed through the second channel, means for limiting the bandwidth of the combined signal to a selected bandwidth, means for controlling each change in frequency of the first local oscillator signal, means for generating a synchronization signal for synchronizing the timing in the scrambling unit and the timing in the unscrambling unit, and means for transmitting the control signal at the time of the synchronization signal from the scrambling unit to the unscrambling unit to initialize the control means in the unscrambling unit;
Dependencies are inferred from the claim text.