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7512237 |
Encryption for optical communications using dynamic subcarrier multiplexing
A multiplexing technique for optical communications used to create a pseudo-random communications signal in the optical domain such that only the sender and/or receiver can decode the signal. The...
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7466507 |
Rangeless servo notch optimization
A method for placing a predetermined number of notch filters in a disc drive servo control system to attenuate noise frequencies, in order of decreasing resonance magnitudes, is disclosed. The...
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7421075 |
Wireless online cryptographic key generation method
A system and method for wireless cryptographic key exchange among participants in a wireless computing network is presented. This allows the authorized participants in the wireless communication...
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7415043 |
Code division multiple access (CDMA) method and apparatus for protecting and authenticating wirelessly transmitted digital information
A spread spectrum method and apparatus for protecting and authenticating wirelessly transmitted digital information using numerous techniques. The apparatus may be a wireless code division multiple...
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7356141 |
Baud rate modulation encoding/decoding method and device for remote controller
A encoding/decoding method and device for a remote controller utilizing a baud rate to encrypt data for transmission. The encoding device includes an encoder encoding an identification code into an...
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7333614 |
System and method for encypting spread spectrum carrier
A system and method for encrypting all channels of a wireless spread spectrum communication at the chip level. The PN sequence is encrypted with one or more encryption sequences and then used to...
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7308104 |
Forward multiple scrambling code generating method and apparatus
Disclosed are a forward multiple scrambling code generating method and apparatus in a communication system. Each base station uses primary scrambling codes and an associated one of secondary...
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7228131 |
IPv6/IPv4 tunneling method
A mobile host MH and its home network HN correspond to both the Internet Protocol version 4 (IPv4) and the Internet Protocol version 6 (IPv6). An authentication server (RS) is accommodated in the...
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6980657 |
Communications system using chaotic synchronized circuits
A chaotic communication system employs transmitting and receiving chaotic oscillating circuits. In an embodiment of the invention employing a Chua circuit as the basic chaotic circuit, the...
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6683958 |
Apparatus and method for embedding and extracting information in analog signals using distributed signal features and replica modulation
Apparatus and methods are provided for embedding or embedding digital data into an analog host or cover signal. A distributed signal feature of the cover signal in a particular domain (time,...
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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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6363325 |
Automotive emergency awareness system
A vehicular emergency awareness system and method is provided. A vehicle is provided with an onboard computer system adapted to receive and process signals generated at an external source. Under...
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6249583 |
On-line signal processing method
A method for encryption and decryption of analog signal, wherein encryption and decryption are performed in analog domain. The transmitter creating digital representations with unique behavior;...
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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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5864625 |
Methods and apparatus for secure optical communications links
Methods and apparatus for providing a secure optical communications link are disclosed. Communications information is encrypted with a security key. An optical beam is then modulated with both the...
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5790591 |
Spread spectrum transmitter and communications system using multiple spreading codes
A spread spectrum transmitter for generating a plurality of spread spectrum codes comprises a shift register having a plurality of stages, with a plurality of tap sets connected to selected ones of...
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5642397 |
Paging system which combines a paging signal with a standard broadcast baseband signal
An electronic paging system and method for transmitting paging signals over a broadcast network, such as a standard pre-existing commercial radio broadcast system, adds paging signals to a normal...
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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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5379345 |
Method and apparatus for the processing of encoded data in conjunction with an audio broadcast
A method and apparatus for the identification and verification of audio transmission segments, such as may be broadcast by a radio station, consists of the generation of a data stream corresponding...
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5305384 |
Apparatus, system and method for transmitting secure signals over narrow spaced channels
An encryption/decryption device, system and method for providing secure communication over a communication channel. The encryption device includes a radio interface unit connected to a conventional...
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5268926 |
Method and apparatus for the simultaneous transmission of separate data signals
A method of simultaneously transmitting first and second data signals by the technique of spectrum spreading by direct sequence, comprises using the first data signal to modulate a spreading code...
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4972479 |
Method and apparatus for providing privacy/security in a communication system
Apparatus and methods are disclosed for providing privacy on communications systems which include radio links, such as cellular telephone, marine radiotelephone, IMTS, and RDSS systems, in a manner...
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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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4841571 |
Privacy signal transmission system
A privacy signal transmission system having a transmitter portion and a receiver portion. The transmitter portion digitizes an analog message signal and enciphers the digitized signal into a...
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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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4658436 |
Disguised transmission system and method
Data signals are transmitted at a variable information rate with variable power so the transmitted information rate and transmitted power level increase and decrease together to simulate high...
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4653069 |
Spread spectrum correlation receiver
A spread spectrum communication system having a correlation receiver for decoding an information signal transmitted on a pseudo-noise (PN) carrier. The receiver synchronizes to the transmitted...
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4652838 |
Phase randomization to reduce detectability of phase or frequency-modulated digital signals
A communications system for conveying information angle-modulated onto a carrier includes a modulator which angle-modulates the data onto the carrier and which also randomly changes the phase of...
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4652699 |
Voice scrambler using frequency-inversion and band-splitting technique
A spectrum inversion type voice scrambler for secret speech communication comprises a first spectrum inversion section, a second inversion section and an adder for summing the outputs of the first...
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4538281 |
Adaptive acquisition of multiple access codes
An adaptive acquisition technique is disclosed for enabling the initial acquisition of a received coded signal in a direct sequence spread spectrum system using multiple access codes for code...
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4516078 |
Variable frequency passband circuit
A variable frequency passband circuit comprising two passband filters and three mixers (front, intermediate and output mixers) connected in a cascade fashion disposed in a signal path. Two VCOs...
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4410911 |
Multiple signal transmission method and system, particularly for television
A method and system for scrambling a plurality of input signals for secure transmission thereof, as well as various methods and systems for television transmission, are disclosed. The disclosed...
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4398214 |
Wired television broadcasting system
There is disclosed a wired television system comprising a source of television signals supplying signals to a transmission network, subscriber stations connected to the network, means for...
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4365110 |
Multiple-destinational cryptosystem for broadcast networks
A method of protecting communications through encryption is disclosed which is particularly useful for multiplexed communications. On the transmit side, each message is multiplied by an enciphering...
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4358857 |
Communication system
1. In combination, a first source for producing a first signal representative of intelligence to be transmitted from one point to another, second source for producing a binary carrier signal having...
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4245346 |
Communication system
1. In combination: a signal source for producing a signal having characteristic variations representative of intelligence, a first code source for producing a first code signal having apparently...
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4206462 |
Secure communication and ranging system
15. In a secure communication system a transmitter comprising first means to modulate a carrier wave with a sub-carrier wave and a desired signal, a code generator synchronized to said sub-carrier...
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4052565 |
Walsh function signal scrambler
A digital speech scrambler system allowing for the transmission of scrambled speech over a narrow bandwidth by sequency limiting the analog speech in a low-pass sequency filter and thereafter...
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3970791 |
Voice controlled disappearing audio delay line
A delay line which disappears under voice control is comprised of a pluray of shift registers delays the incoming voice signal to permit transmission of the voice scrambler preamble. The delay is...
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3925611 |
Combined scrambler-encoder for multilevel digital data
A high-speed digital data transmission system combines quadrature amplitude modulation with scrambling-descrambling, differential amplitude coding-decoding, and Gray-to-rotational coding-decoding...
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3914534 |
Methods and apparatus for scrambling and unscrambling premium television channels
A subscriber television system is disclosed having a central unit coupled by way of a plurality of video channels and a plurality of intermediate processors to individual subscriber locations. The...
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3885089 |
Television scrambling system
A subscription television scrambling and unscrambling system. In one embodiment, at the transmitter end of the system, first means selectively alternates or scrambles at least two television...
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3826863 |
SUBSCRIPTION TELEVISION SYSTEM USING AUDIO AND VIDEO CARRIER REVERSAL
A subscription television system reverses the audio and video carriers within a particular channel on a random basis. A switching signal, nominally one Mhz beneath the video carrier, is transmitted...
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3789131 |
SELECTIVE CODING SYSTEM FOR SUBSCRIPTION TELEVISION
A system for coding and decoding television signals in a subscription television system provides means for alternately switching a television signal between channels at a transmitting center and...
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3654604 |
SECURE COMMUNICATIONS CONTROL SYSTEM
A system for generating secure command signals at a remote station, such as a branch bank, under the control of a central station, such as a main bank. Random words are independently generated at...
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3568154 |
SECURITY ALARM TRANSMISSION OF RADIO FREQUENCY CODED PULSES
A security alarm system wherein an alarm signal is sent by a transmitter which generates a radiofrequency carrier wave modulated by an audiofrequency signal which is further pulse code modulated. A...
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3476880 |
TRANSMITTING SYSTEM
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3204034 |
Orthogonal polynomial multiplex transmission systems
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3099835 |
Phase coded hyperbolic navigation system
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3061669 |
Multiplex television system
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