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7545929 |
Analog encryption
The ability to securely transmit information between two locations is of paramount importance in today's communication systems. Before the invention of digital transmission methods, analog...
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7391867 |
Graphical display of QKD system statistics
Systems and methods for graphically displaying statistical information relating to the operation of a quantum key distribution (QKD) system. The method includes exchanging quantum photons between...
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7379878 |
Information encoding apparatus and method, information decoding apparatus and method, recording medium utilizing spectral switching for embedding additional information in an audio signal
An information encoding apparatus and method, an information decoding apparatus and method, a recording medium, and a program make it possible to embed information without causing an increase in...
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7333608 |
Analog scrambler
An analog signal scrambler/de-scrambler includes a receiver for receiving an analog signal and converting the signal into an intermediate frequency signal. A generator generates a pseudo-random...
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7298840 |
Method and system for data integrity protection
A method of authenticating a message ( 111 ) received via a transmission channel ( 108 ) using a Message Authentication Code (MAC). The message comprises a message body ( 114 ) and a tag ( 116 )...
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7219082 |
Financial management system
A financial transaction network includes a customer network serviced by a host processor. The financial transaction network provides customers with a plurality of diverse and interchangeable...
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7076659 |
Enhanced method for digital data hiding
A method is provided for enhanced spread spectrum watermarking. The improved watermarking method includes: receiving host data which is expressed in a transform domain by a plurality of host...
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7051203 |
Data watermarks created by using an uneven sampling period
Input signals are electronically watermarked using an uneven or non-uniform sampling rate. The uneven or non-uniform sampling may be pseudo-random. The uneven or non-uniform sampling meets the...
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6993153 |
Self-orienting watermarks
A watermarking method converts a watermark message into a Frequency Shift Keying (FSK) signal and embeds the FSK signal in a host signal. The spectral properties of the FSK watermark signal...
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6973190 |
Method for protecting an electronic system with modular exponentiation-based cryptography against attacks by physical analysis
The invention concerns a method for protecting an electronic system implementing a cryptographic calculation process involving a modular exponentiation of a quantity (x), said modular...
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6823455 |
Method for robust watermarking of content
One inventive aspect pertains to a watermarking mechanism that allows a watermark to be determined from only a part of the video sequence without human intervention and without reference to the...
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6731757 |
Multichannel digital signal generation method and apparatus
A method of and apparatus for digitally generating a broadband signal comprising a plurality of CW or quadrature modulated signals having incrementally related frequencies wherein said plurality of...
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6501841 |
Method for providing security for a transmission of information through a plurality of frequency orthogonal subchannels
One embodiment of the present invention is a method for providing security for a transmission of information in an ADSL environment using a DMT modulation technique. The order of the frequency...
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6389138 |
Method and apparatus for generating a complex scrambling code sequence
A complex spreading and/or scrambling code sequence generation system uses a first complex code sequence having at least two components and a second complex code sequence having at least two...
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6345100 |
Robust watermark method and apparatus for digital signals
Watermark data is encoded in a digitized signal by forming a noise threshold spectrum which represents a maximum amount of imperceptible noise, spread-spectrum chipping the noise threshold spectrum...
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6229897 |
Apparatus and method of secured analog voice communication
An apparatus and method for improved security in wire or wireless communication systems includes scrambling the audio signal, combining a masking signal with the scrambled audio signal, and then...
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5796838 |
Method and apparatus for performing frequency spectrum inversion
An apparatus and method for creating voice privacy by performing frequency spectrum inversion in electronic voice transmission systems includes the steps of digitizing an analog signal and...
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5768374 |
Apparatus and method for continuous scrambling while transmitting or receiving synchronization data
An apparatus and device for continuously scrambling audio while transmitting or receiving synchronization data. When transmitting, synchronization data will be substituted for scrambled audio but...
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5757921 |
Radio communication apparatus having common oscillator applied for PLL, conversion and scramble/descramble circuits
A superheterodyne receiving circuit and a superheterodyne transmitting circuit are provided. A PLL forms a local oscillation signal in the receiving circuit, and a PLL forms a carrier signal in the...
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5671284 |
Data encryptor having a scalable clock
A method for encrypting and decrypting digital data. The digital data is initially latched by an input register. Sixteen separate cipher stages cascaded in series are used to encrypt the digital...
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5528692 |
Frequency inversion scrambler with integrated high-pass filter having autozero to remove internal DC offset
A frequency inversion scrambler in a cordless telephone utilizes an integrated high-pass filter (14) between a first stage low-pass filter (12) and modulator (16) to reduce the filter order while...
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5471531 |
Method and apparatus for low cost audio scrambling and descrambling
Audio signals are descrambled by double sideband modulating the scrambled audio signal with a modulation carrier having a carrier frequency slightly above the highest audio signal present in the...
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5400404 |
Modulation/demodulation circuit and communication system utilizing the same
The present invention provides a modulation/ demodulation circuit and a communication system utilizing the modulation/demodulation circuit. The modulation/ demodulation circuit can be operated in...
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5377223 |
Notch filtering a spread spectrum signal using fourier series coefficients
A transmitter and receiver for spread spectrum communications using a Fourier series coefficients module, a notch gate, a fast Fourier transform module, and memory. The Fourier series coefficient...
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5335279 |
Digital voice-band spectrum inversion apparatus
A digital speech-band spectrum inversion apparatus for use in a cordless telephone system provides transmission security of the voice signal between the handset (10) and the base station (18). The...
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5168522 |
Wireless telephone with frequency inversion scrambling
The wireless telephone of the present invention is comprised of a base unit, coupled to a land-line telephone system, and a remote unit that communicates with the base unit over radio frequencies....
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5159631 |
Audio scrambling system using in-band carrier
Audio signals are scrambled by single side band modulating with a modulation signal carrier having a frequency lying within the audio frequency band so that the signals are frequency translated...
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5144666 |
Decoder to decode an encrypted sound
Decoder for encrypted sound signals which are encrypted by modulating the sound signals on an alternating carrier signal having a frequency which is generally unknown to receiving parties. A...
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5140635 |
Wireless telephone with frequency inversion scrambling
The wireless telephone of the present invention is comprised of a base unit, coupled to a land-line telephone system, and a remote unit that communicates with the base unit over radio frequencies....
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5065430 |
Voice band splitting scrambler
Disclosed is a voice band splitting scrambler. To simplify the hardware thereof, the apparatus comprises a band splitting unit (11) for splitting an input voice signal into a plurality of band...
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5058159 |
Method and system for scrambling and descrambling audio information signals
Audio signals are scrambled by inverting the original; frequency spectrum so that frequency portions originally lying at the lower end of the audio frequency band are shifted to the upper end while...
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5020104 |
Method of reducing the useful bandwidth of bandwidth-limited signals by coding and decoding the signals, and system to carry out the method
The useful bandwidth of a bandwidth-limited input signal (s(t)) is reduced, to obtain a coded signal (q(t)) by forming a combined input and feedback signal, low-pass filtering the combined signal,...
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5018198 |
Speech privacy processing method and apparatus therefor
A speech privacy processing apparatus is disclosed including: a unit for obtaining the number of coefficients commonly included in a set of coefficients obtained by Fourier transformation and...
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4984219 |
Method and apparatus for decoding of frequency inversion based scramblers
A method and apparatus for decoding of frequency inversion based scramblers is disclosed. A quadrature amplitude modulation detector determines the frequency of the tone used for inverting the...
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4969191 |
Fully digital phase-locked loop
A fully digital phase-locked loop comprises a sampler (1), an analog-to-digital converter (2), two quadrature demodulators (3 and 4) and their associated filters (5 and 6), and a decision logic (7)...
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4949378 |
Toy helmet for scrambled communications
A toy helmet that permits the wearer to speak as to generate unintelligible noise so far as bystanders are concerned but which can be understood by another child wearing an identical helmet. Each...
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4914696 |
Communications system with tandem scrambling devices
An intermediate scrambling device for a radiotelephone system is disclosed by which it is possible to establish and maintain scrambled communications between an originating scrambler terminal and...
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4908860 |
System for the secret transmission of audio signals and television receiver for receiving such signals
Encoding is realized by means of a first low-pass input filter (21), a first modulator (20), a second low-pass filter (19), a second modulator (18) whose modulating signal has a frequency which is...
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4888799 |
Scrambling of signals by inversion
The present invention is directed to an inversion scrambler and unscrambler having pseudo-randomly controlled polarity-reversing switches to invert and re-invert, respectively, an audio signal so...
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4827507 |
Duplex analog scrambler
An analog frequency inversion scrambler employing an exchange of random number seeds between an originating scrambler and an answering scrambler to create two pseudo-random frequency hopping...
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4817141 |
Confidential communication system
The respective feature parameters extracted from a speech signal is converted into the corresponding line spectrum data in a first frequency band obtained by dividing the speech signal frequency...
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4802219 |
Method and apparatus for distorting a speech signal
Method of distorting a speech signal by rearranging and/or reversing frequency bands in this signal. The speech signal is divided into a plurality of sub-bands by filtering, and the sub-bands are...
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4799257 |
Wireless transmission system for PM modulation signal
A wireless transmitter for PM (phase modulation) signal with a spectrum scrambler for relocation of input spectrum for privacy purposes is comprised of a differential circuit coupled with an input...
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4773092 |
Speech scramblers
A band scrambler which processes only time domain samples is described. The band scrambler has the effect of dividing the input signal spectrum into N sub-bands. The N sub-bands are permuted such...
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4750205 |
Frequency or time domain speech scrambling technique and system which does not require any frame synchronization
The present invention relates to speech scrambling techniques and systems and in particular to a frequency or time domain speech scrambling technique and system which does not require any frame...
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4747137 |
Speech scrambler
A speech scrambler is disclosed, in which a frequency spectrum obtained by an orthogonal transform of a time domain signal is divided into a plurality of blocks in the frequency domain. One of the...
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4726064 |
Wireless reception system
A wireless receiver for a PM (phase modulation) signal with a spectrum scrambling for relocation of speech spectrums for the privacy of purpose is comprised of an antenna for receiving PM modulated...
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4659875 |
Electronic system for the secret transmission of audio signals
System for the secret transmission of audio signals having at one end a coding arrangement comprising an input low-pass filter which selects the secret audio signals to be transmitted, two parallel...
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4612414 |
Secure voice transmission
Voice signals are transmitted over a voiceband telephone channel with a high degree of security and good voice quality by applying to the transmission channel a first signal which includes digital...
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4581765 |
Information security system
A system is disclosed for encoding and decoding the audio signal portion of a television signal to prevent unauthorized reception of the audio signal. At the encoding stage, the audio signal is...
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