| 6690795 |
Multiple keys for decrypting data in restricted-access television system |
| Feb-10-2004 |
An encryption system for restricted-access television systems. Multiple decryption keys are used to decrypt encrypted material which is transmitted to customers of a restricted-access television system. |
| 6658113 |
Apparatus and method for concealing data bursts in an analog scrambler using audio repetition |
| Dec-2-2003 |
An apparatus and method for concealing data bursts in an analog scrambler using parts of the audio of a signal in substitution for the data bursts. What otherwise would be periodic data bursts appearing... |
| 6658112 |
Voice decoder and method for detecting channel errors using spectral energy evolution |
| Dec-2-2003 |
A voice decoder detects channel errors and loss of cryptographic synchronization using the change in spectral energy between sequential frames. The change in energy between frames is determined between... |
| 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... |
| 6272633 |
Methods and apparatus for transmitting, receiving, and processing secure voice over internet protocol |
| Aug-7-2001 |
This disclosure describes systems and methods for processing voice data for secure transmission and secure receipt over a network, such as the Internet. The systems and methods include the processing of... |
| 6266412 |
Encrypting speech coder |
| Jul-24-2001 |
Disclosed is an encrypting speech processor architecture that provides enhanced security without the use of external cryptosync and with minimal speech degradation. This is accomplished by incorporating... |
| 6131160 |
Method and apparatus for an adapter card providing conditional access in a communication system |
| Oct-10-2000 |
A method and apparatus for an adapter card, for use in a computer, to provide conditional access by the computer to incoming data streams while maintaining the security of information by maintaining a... |
| 6078668 |
Apparatus and method for concealing data bursts in an analog scrambler using audio repetition |
| Jun-20-2000 |
An apparatus and method for concealing data bursts in an analog scrambler using audio repetition. What otherwise would be periodic data bursts appearing at the audio output are replaced with samples from... |
| 6078666 |
Audio signal processing method and related device with block order switching |
| Jun-20-2000 |
An audio signal processing method and unit for scrambling and descrambling audio signals accompanying video signals. The audio signal processing method comprises steps of dividing digital audio signals... |
| 5949878 |
Method and apparatus for providing voice privacy in electronic communication systems |
| Sep-7-1999 |
An apparatus and method for creating voice privacy in electronic voice transmission systems includes the steps of digitizing an analog signal and inverting and rotating the frequency spectrum of the digitized... |
| 5930365 |
Digital data shuffling/de-shuffling system |
| Jul-27-1999 |
The invention provides a digital data shuffling/de-shuffling system so that information data is not understood or deciphered by unauthorized third party. Included are a system for generating plural bits... |
| 5796838 |
Method and apparatus for performing frequency spectrum inversion |
| Aug-18-1998 |
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 inverting the... |
| 5787180 |
Method of connecting a scrambler or encryption device to a hand-held portable cellular telephone |
| Jul-28-1998 |
An apparatus and method for voice privacy for cellular phones includes generic connection points to make it universal for most cellular phones. The connection points include the speaker and microphone... |
| 5778073 |
Method and device for speech encryption and decryption in voice transmission |
| Jul-7-1998 |
A digitized real voice signal is converted via complex filtering into a complex signal that is subjected to sampling rate reduction, the bandwidth of the respective complex filter corresponding to the... |
| 5768374 |
Apparatus and method for continuous scrambling while transmitting or receiving synchronization data |
| Jun-16-1998 |
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 the audio... |
| 5712905 |
Sequential digital profile for processing analog signals |
| Jan-27-1998 |
An object of the present invention is to provide a method for creating an unique digital representation of multiple analog signals, and more particularly to provide a method for development of a sequential... |
| 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... |
| 5488663 |
Encoding methods for generating a digital signal containing modulated bit allocation information, and record carriers containing that signal |
| Jan-30-1996 |
Transmission system for transmitting and receiving, and subband encoding methods for generating for transmission, digital signals containing modulated bit allocation information; and record carriers containing... |
| 5454040 |
Digital control of analog systems |
| Sep-26-1995 |
An audio mixing console incorporates a number of audio modules connected in series, with the first module being serially connected to a digital controller. The digital controller provides digital signals... |
| 5412719 |
Radio paging system with voice transfer function and radio pager |
| May-2-1995 |
A radio paging system with voice transfer function for transmitting a voice message input from an ordinary push-button telephone set to a small-sized receive-only unsophisticated radio pager. A paging... |
| 5410599 |
Voice and data encryption device |
| Apr-25-1995 |
A portable voice and data encryption device designed to be used with normal wideband telephone and cellular telephones, computers and facsimile machines to transmit voice and data in encrypted form. The... |
| 5375171 |
Transmission system, and transmitter and receiver used in the transmission system for transmitting and receiving digital signals containing modulated bit allocation information |
| Dec-20-1994 |
Transmission system, and transmitter and receiver for use in the transmission system for transmitting and receiving digital signals containing modulated bit allocation information. The transmitter encodes... |
| 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... |
| 5101432 |
Signal encryption |
| Mar-31-1992 |
Method and apparatus for encrypting and subsequently decrypting an analog or digital signal are disclosed. During encryption the signal waveform is transformed by a substantially continuous non-linear... |
| 5091941 |
Secure voice data transmission system |
| Feb-25-1992 |
In the secure radio transmission system of the present invention the sign bit for each byte of audio digital data is scrambled to generate a scrambled sign bit. By altering the sign bit, the resultant... |
| 4969191 |
Fully digital phase-locked loop |
| Nov-6-1990 |
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) effecting... |
| 4953211 |
Encryption apparatus |
| Aug-28-1990 |
Encryption apparatus mainly intended for encrypting speech signals samples a signal to be encrypted at two differing rates, and reads the sampled signal into storage means at one of said rates and reads... |
| 4949378 |
Toy helmet for scrambled communications |
| Aug-14-1990 |
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 helmet... |
| 4841571 |
Privacy signal transmission system |
| Jun-20-1989 |
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 privacy signal... |
| 4837821 |
Signal transmission system having encoder/decoder without frame synchronization signal |
| Jun-6-1989 |
A privacy code-type signal transmission system includes a transmitter having a signal sampler for producing analog samples of an analog audio signal, an analog to digital converter, a scrambler, a multi-level... |
| 4823380 |
Voice changer |
| Apr-18-1989 |
A voice changer for use generally with a telephone includes a first port for receiving signals from a microphone or the hand set, a second port for connection to a microphone or a telphone set, and a voice... |
| 4817141 |
Confidential communication system |
| Mar-28-1989 |
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 band.... |
| 4773092 |
Speech scramblers |
| Sep-20-1988 |
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 that... |
| 4771455 |
Scrambling apparatus |
| Sep-13-1988 |
The present invention relates to a scrambling apparatus and particularly to a scrambling apparatus in which a scrambling signal is inserted into a main signal in a predetermined period (period of duration... |
| 4750205 |
Frequency or time domain speech scrambling technique and system which does not require any frame synchronization |
| Jun-7-1988 |
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 synchronization.... |
| 4747137 |
Speech scrambler |
| May-24-1988 |
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 blocks... |
| 4742543 |
Video transmission system |
| May-3-1988 |
A subscriber cable television system uses predominantly digital signal processing techniques and has extremely high security and an increased capacity for transmitting program and customer data to individual... |
| 4706282 |
Decoder for a recorder-decoder system |
| Nov-10-1987 |
An improved decoder for a recorder-decoder system wherein a threshold level detector is included in the decoder. The recorder provides for the recording of an audio signal plus a data signal. The data... |
| 4591673 |
Frequency or time domain speech scrambling technique and system which does not require any frame synchronization |
| May-27-1986 |
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 synchronization.... |
| 4550222 |
Process for interception-protected frequency band compressed transmission of speech signals |
| Oct-29-1985 |
In order to achieve a good masking, together with minimum bandwidth requirement of sample values of spectral channels which are to be transmitted in the timing of consecutive analysis intervals in a time... |
| 4443660 |
System and method for encrypting a voice signal |
| Apr-17-1984 |
A system and method are disclosed for encrypting a voice signal. The input signal is filtered to provide a signal in a first path with components in a higher frequency band and a signal in a second path... |
| 4433211 |
Privacy communication system employing time/frequency transformation |
| Feb-21-1984 |
A privacy communication system digitizes a voice signal and divides the signal into different frequency bands or time segments and shifts the bands or segments in frequency and/or time under control of... |
| 4398062 |
Apparatus for privacy transmission in system having bandwidth constraint |
| Aug-9-1983 |
Source intelligence within a predetermined bandwidth is normally provided to a transmission channel having a bandwidth constraint of the predetermined bandwidth. For privacy transmission, a first pulse... |
| 4379205 |
Analog signal scrambling system |
| Apr-5-1983 |
A speech scrambling system using discrete prolate spheroidal sequence coefficients (PC). The problem is to provide high fidelity and high security in a scrambling system while limiting the bandwidth of... |
| 4330689 |
Multirate digital voice communication processor |
| May-18-1982 |
To provide alternative operation at 2.4 or 9.6 Kb/s bit rates, a multirate igital processor generates a data frame of 216 bits representing sync and voice encoded at both rates, with the 2.4 Kb/s embedded... |
| 4318125 |
Solid state digital audio scrambler system for teletransmission of audio intelligence through a television system |
| Mar-2-1982 |
An audio scrambler digitally samples a continuous audio signal, scrambles the derived samples and inserts at least one scrambled sample in the unoccupied region of the video signals of a video system for... |
| 4305152 |
Security communication system |
| Dec-8-1981 |
A security communication system comprises a transmission apparatus including a scrambling circuit for scrambling an information signal according to a specific code and a reception apparatus including a... |
| 4266095 |
Binary code randomizing system |
| May-5-1981 |
1. In a secret communication system including a source of an intelligence signal wave, means for periodically sampling said signal wave at predetermined intervals, and means for developing from the samples... |
| 4126761 |
Method of and means for processing an audio frequency signal to conceal intelligility |
| Nov-21-1978 |
An input audio frequency analog signal, for example, speech, which is to be passed through a noisy transmission channel, is scrambled at the sending end by repetitively performing a modulo-v (MOD v) addition... |
