Analog privacy scrambler and scrambling method
AssigneeLockheed Martin Corporation
InventorsDennis L. Wilson, Julius Lange, Andrew Brown
Life of this patent
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Abstract
A system and method for maintaining privacy in transmission of a high bandwidth analog signal. A preferred system and method breaks an input signal into bands and then uses Walsh codes to overlay many signals on top of each other with a set of phase modulators to establish scrambling of the input signal. The scrambled signal is then transmitted. The received scrambled signal has the phase modulation removed and an inverse Walsh transform recovers the original bands. The recovered bands are added together to recover the original signal. The system and method use techniques that establish synchronization and phase coherency complete the process.
Claims9
An analog privacy scrambling system comprising:
- a transmitter comprising:
- a band subdivision circuit for receiving an analog input signal that is to be scrambled that segments the analog signal;
- a coding circuit that combines the segments using a Walsh transform, for example,
- a phase modulation circuit for randomly transforming the combined segments to produce a scrambled phase modulated signal;
- and
- a transmit circuit for transmitting the scrambled phase modulated signal;
- and
- a receiver comprising:
- a band selection circuit that receives and segments the transmitted scrambled phase modulated signal;
- phase demodulation circuit that has phase modulation synchronized with the phase modulation imposed at the transmitter to shift the segmented signal to baseband and remove the phase modulation;
- an inverse coding circuit that recovers the original baseband segments from the segmented signal;
- and
- a signal composition circuit that remodulates the original baseband segments to their original frequencies and adds the segments to reproduce the original signal.
An analog privacy scrambling method comprising the steps of:
- segmenting an analog signal into a plurality of segments;
- combining the plurality of segments to obscure individual signals by burying the signal in a number of other added signals;
- phase modulating the combined signals to introduce a random transformation of the segments;
- transmitting the phase modulated signals;
- receiving the transmitted phase modulated signals;
- segmenting the received signals using segment selection;
- phase demodulating the segmented signals to remove the phase modulation from the segmented signals;
- recovering the original baseband segments from the phase demodulated signals;
- remodulating the original baseband segments to their original frequencies;
- and
- adding the remodulated segments to reproduce the original analog signal.
An analog privacy scrambling method comprising the steps of:
- segmenting an analog signal;
- combining the segments using a Walsh transform;
- phase modulating the combined segments to produce a scrambled signal;
- transmitting the scrambled signal;
- receiving the scrambled signal;
- segmenting the received scrambled signal;
- removing the phase modulation of the received segments;
- inverse Walsh transforming the segments to recover the original baseband segments;
- remodulating the segments to their original frequencies;
- and
- adding the remodulated segments to reproduce the original signal.
Dependencies are inferred from the claim text.