| 6947559 |
Random number generator based on turbulent convection |
| Sep-20-2005 |
A method for generating random numbers includes the steps of providing a liquid crystal cell containing a liquid crystal material, wherein a potential difference is applied across said liquid crystal material... |
| 6801626 |
Cryptographic key distribution using light pulses of three macroscopic quantum states |
| Oct-5-2004 |
At a sender site of a secure communication network, a first coherent light pulse sequence is phase modulated with a random bit sequence by a phase modulator, and a second coherent light pulse sequence... |
| 6778669 |
Quantum encryption device |
| Aug-17-2004 |
A quantum encryption device comprises a transmitter and a receiver between which an encrypted piece of information is transmitted. The transmitter comprises at least means to send a first packet of photons... |
| 6711262 |
Procedure for the control of applications stored in a subscriber identity module |
| Mar-23-2004 |
A procedure for the control of applications stored in a user's subscriber identity module (SIM) in a data communication system that includes a data communication network, a terminal device connected to... |
| 6498851 |
Data encryption and signal scrambling using programmable data conversion arrays |
| Dec-24-2002 |
A scrambling or encryption method involves analog-to-digital, digital-to-analog, analog-to-analog or digital-to-digital conversions that are constructed from one or more analog-to-digital or digital-to-analog... |
| 6175639 |
Digital data encode system |
| Jan-16-2001 |
A digital data encode system for inserting water mark data into digital data signals having a series of field data by use of a water mark data inserting device, the digital data encode system has a field... |
| 5668879 |
Audio scrambling system for scrambling and descrambling audio signals |
| Sep-16-1997 |
A scrambling system includes a scrambling apparatus and a descrambling apparatus for scrambling and descrambling digital audio codes having plural sub-band units. Each sub-band unit includes at least a... |
| 5455861 |
Secure telecommunications |
| Oct-3-1995 |
A security node disposed in the telecommunications network connecting calling and called parties transforms information (which can be voice, data, facsimile, video and other types of calls or messages)... |
| 5434920 |
Secure telecommunications |
| Jul-18-1995 |
A security node disposed in the telecommunications network connecting calling and called parties transforms information (which can be voice, data, facsimile, video and other types of calls or messages)... |
| 5216692 |
Method and apparatus for adjusting a power control threshold in a communication system |
| Jun-1-1993 |
A method and apparatus is provided for maintaining received signal power levels at an average level when a signal power estimate is on average similar to the average of actually received signal power levels.... |
| 5199074 |
Encryption system |
| Mar-30-1993 |
A communication system transmits and receives encrypted digital signal samples. The system includes a generator for generating digital signal samples to be encrypted and an encryption memory for storing... |
| 5177785 |
Method and system for secure telecommunications |
| Jan-5-1993 |
There is disclosed a method and system for injecting a number of different signal patterns onto a tone encoded telecommunications line for the purpose of preventing unauthorized eavesdropping. The system... |
| 5159611 |
Variable rate coder |
| Oct-27-1992 |
A variable rate coder for transforming an input signal into a low bit rate digital signal, comprising: a plurality of coding units each comprising an output quantizer having a different number of output... |
| 4985919 |
Secure communication control system |
| Jan-15-1991 |
Encoder/decoders are associated with conventional local and far-end communications equipment such as facsimile machines. Information to be faxed is encoded at one end, transmitted to the other end, and... |
| 4979188 |
Spectrally efficient method for communicating an information signal |
| Dec-18-1990 |
According to the invention, an information signal, such as a information signal, is sampled, quantized and processed digitally through an information encoder. Digitally processed samples produced by the... |
| 4852166 |
Analogue scrambling system with dynamic band permutation |
| Jul-25-1989 |
An analogue scrambling system with dynamic band permutation in which the speech signal is filtered (1), sampled (2) at the rate f.sub.e, digitized (3), transformed by means of an analysis filter bank (4)... |
| 4754481 |
Expanded partial response processing for analog signal enciphering and the like |
| Jun-28-1988 |
Partial response signal processing is applied to samples of an analog signal quantized in an amplitude range having a sufficient number of levels that a sample amplitude error of a small percentage of... |
| 4365111 |
Cipher apparatus for multiplex pulse code modulation systems |
| Dec-21-1982 |
23. In a secret communication system, the combination of: a source of an intelligence signal wave and a source of a noise wave; means for combining said waves; means for periodically sampling said combined... |
| 4343970 |
Signaling system |
| Aug-10-1982 |
1. In electrical signaling in which the signal varies in amplitude from instant to instant, and at any one instant has an amplitude equal to one of a limited number of values having a total range in excess... |
| 4283602 |
Cryptographically secure communication system |
| Aug-11-1981 |
This relates to a cryptographically secure communication system employed with an analog input, an analog output and a transmission medium each having a given low frequency pass band with a predetermined... |
| 4278840 |
Dynamic frequency and time voice encryption system and method |
| Jul-14-1981 |
A voice scrambler system (10) for encryption of a voice signal is provided. The voice scrambler system (10) includes a first generator (124) for generating a fixed frequency signal. A second generator... |
| 4178474 |
Signaling system |
| Dec-11-1979 |
6. In a key pulse system for generating key pulses of definite length and highly irregular magnitude with intervening spaces, cyclically operating devices for generating groups of irregular sequences of... |
| 4156108 |
Pulse producing system for secrecy transmissions |
| May-22-1979 |
1. In a system for transmitting a quantized signal having a definite maximum value, a reentry circuit comprising a cyclically operating electronic stepper having a cycle length in step-positions corresponding... |
| 3983327 |
Electrical signaling |
| Sep-28-1976 |
1. A signal value permuting system comprising a succession of reentry circuits having successively higher reentry point values, means to send signals through a plurality of said reentry circuits in tandem,... |
| 3983326 |
Key pulse generator for secrecy signalling circuit |
| Sep-28-1976 |
6. In a pulse generating system, means for producing irregular pulses in each of a number of separate circuits, an output for each of said circuits, a pair of holding devices for each of said circuits,... |
| 3979558 |
Signaling system |
| Sep-7-1976 |
1. In a speech privacy transmission system, means for analyzing speech currents into component frequency band currents in a plurality of separate circuits, a corresponding plurality of separate transmission... |
| 3976839 |
Telephone privacy system |
| Aug-24-1976 |
1. In combination, means for receiving a signal wave accompanied by a pilot impulse, means to combine with the received signal wave a locally produced wave in predetermined phase relation comprising means... |
| 3968454 |
Signaling circuit |
| Jul-6-1976 |
1. In a pulse-producing system, a plurality of space discharge tube ring circuits each comprising a different number of stages, the numbers of stages in the rings having no common factor greater than one,... |
| 3967067 |
Secret telephony |
| Jun-29-1976 |
1. In a system of secret transmission of speech, means to subdivide speech waves constituting a message into a plurality of narrow frequency bands, means to integrate the energy in each band, means individual... |
| 3965297 |
Secret communication signal generating system |
| Jun-22-1976 |
1. A key generating circuit for constructing a six-valued key by combination of signals of smaller ranges of values comprising means to produce two-valued signals of highly irregular occurrence, one signal... |
| 3965296 |
Signaling system |
| Jun-22-1976 |
1. In a signaling system, a plurality of input circuits carrying signal currents, a corresponding plurality of individual output channels, a privacy equipment common to said circuits and channels for rendering... |
| 3953678 |
Speech component key signaling system with code combinations |
| Apr-27-1976 |
1. In secret telephony, means to analyze input speech waves into low frequency speech-defining currents simultaneously existent in a plurality of separate circuit paths, means to add secret key currents... |
| 3953677 |
Key signaling system with multiple pulse generators |
| Apr-27-1976 |
1. In a secret signaling system, means at a station for providing a plurality of different keys for use one at a time for enciphering signals to be sent from said station, means at said station when transmitting... |
| 3944745 |
Secret signaling system with means for preventing key disclosure |
| Mar-16-1976 |
1. In a signaling system for transmitting with secrecy signals of varying amplitude, means to encipher said signals comprising means to produce variable key currents and means to combine said signals with... |
| 3944744 |
Matrix coding secret signalling system |
| Mar-16-1976 |
1. In a scrambling system for translating input message values into output currents of substantially random occurrence of values, separate message input circuits for each message value, separate output... |
| 3934078 |
Key generating system |
| Jan-20-1976 |
1. In a key pulse generating circuit for producing key pulses varying in amplitude in highly irregular manner, said pulses occurring at a given rate, means to generate high speed off-on pulses at a rate... |
