| 7024018 |
Watermark position modulation |
| Apr-4-2006 |
Methods and apparatus are provided for embedding information in a host signal based on the positioning of watermarks within the host signal. An embedder provides (i.e. embeds) a plurality of watermarks... |
| 7003118 |
High performance IPSEC hardware accelerator for packet classification |
| Feb-21-2006 |
An architecture for a high performance IPSEC accelerator. The architecture includes components for scanning fields of packets, programming an IPSEC services device according to the scanned fields, and... |
| 6996237 |
Apparatus and methods for including codes in audio signals |
| Feb-7-2006 |
Apparatus and methods for including a code having at least one code frequency component in an audio signal are provided. The abilities of various frequency components in the audio signal to mask the code... |
| 6961431 |
Analog privacy scrambler and scrambling method |
| Nov-1-2005 |
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... |
| 6879703 |
Method and apparatus for watermarking images |
| Apr-12-2005 |
Digital watermarks are embedded in image data (102)in order to enable authentication of the image data and/or replacement of rejected portions of the image data. Authentication codes are derived by comparing... |
| 6862355 |
Message reconstruction from partial detection |
| Mar-1-2005 |
A method and system for reliably detecting encoded messages included in audio media data in varying acoustic environments, where only a portion of the predetermined message may have been received or detected. |
| 6430291 |
Method and device for controlling information signal recording |
| Aug-6-2002 |
An anti-duplication control signal detection section detects an anti-duplication control signal added on a video signal S1 and supplies it to a system controller as a duplication prevention control information... |
| 6421445 |
Apparatus and methods for including codes in audio signals |
| Jul-16-2002 |
Apparatus and methods for including a code having at least one code frequency component in an audio signal are provided. The abilities of various frequency components in the audio signal to mask the code... |
| 6330335 |
Audio steganography |
| Dec-11-2001 |
An identification code signal is hidden in a carrier signal (such as an electronic data signal or a physical medium) in a manner that permits the identification signal later to be discerned. The carrier... |
| 6175627 |
Apparatus and method for embedding and extracting information in analog signals using distributed signal features |
| Jan-16-2001 |
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, frequency... |
| 6151578 |
System for broadcast of data in an audio signal by substitution of imperceptible audio band with data |
| Nov-21-2000 |
A system for broadcasting data (D) that can transmit information in the passband of a broadcast audio-frequency signal (S). The system can determine at least one frequency band (F'.sub.13, . . . , F'.sub.24)... |
| 6035177 |
Simultaneous transmission of ancillary and audio signals by means of perceptual coding |
| Mar-7-2000 |
A communication system for simultaneously transmitting ancillary codes and audio signals via a conventional audio communications channel using perceptual coding techniques is disclosed. An encoder monitors... |
| 5940135 |
Apparatus and method for encoding and decoding information in analog signals |
| Aug-17-1999 |
Apparatus and methods are provided for encoding, storing and decoding auxiliary information on an analog source signal in a way which has minimal impact on the human perception of the source information... |
| 5764763 |
Apparatus and methods for including codes in audio signals and decoding |
| Jun-9-1998 |
Apparatus and methods for including a code having at least one code frequency component in an audio signal are provided. The abilities of various frequency components in the audio signal to mask the code... |
| 5493612 |
Secure communication keying system |
| Feb-20-1996 |
The secure communication keying system has a noise generator whose output a predetermined finite band of noise within, for example, the zero to eleven hundred cycle per second range. The noise generator... |
| 5450490 |
Apparatus and methods for including codes in audio signals and decoding |
| Sep-12-1995 |
Apparatus and methods for including a code having at least one code frequency component in an audio signal are provided. The abilities of various frequency components in the audio signal to mask the code... |
| 5319735 |
Embedded signalling |
| Jun-7-1994 |
A code signal representing a sequence of code symbols carrying digital information is generated with the frequency components of the code signal being essentially confined to a preselected signalling band... |
| 5181243 |
System and method for communications security protection |
| Jan-19-1993 |
A system and method are disclosed for preventing intelligible interception of information signals transmitted over a two-direction line. A masking signal is applied through a hybrid circuit at the receiving... |
| 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... |
| 5168519 |
System and method for securing DTMF transmission |
| Dec-1-1992 |
A technique for inhibiting intelligible interception of information signals transmitted over a line from a first site to a second site. A masking signal is applied to the line immediately upon the detection... |
| 5148478 |
System and method for communications security protection |
| Sep-15-1992 |
A system and method are disclosed for preventing intelligible interception of information signals transmitted over a two-direction line. A masking signal is applied through a hybrid circuit at the receiving... |
| 5113437 |
Signal identification system |
| May-12-1992 |
A signal identification system, suitable for producing an identification code on a sound track recording is described. The system includes an encoder 209 effective to eliminate a variable sequence of frequency... |
| 5036542 |
Audio surveillance discouragement apparatus and method |
| Jul-30-1991 |
An audio surveillance discouragement apparatus or system comprising, at least, first generating device, second generating device, first speaker and second speaker. The first speaker is coupled to the first... |
| 4972469 |
System and method for communications security protection |
| Nov-20-1990 |
A system and method are disclosed for preventing intelligible interception of information signals transmitted over a two-direction line. A masking signal is applied through a hybrid circuit at the receiving... |
| 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... |
| 4674124 |
Multichannel masking sound generator |
| Jun-16-1987 |
In the masking sound source disclosed herein, easily adjustable but matching acoustic energy spectrums are obtained from different channels by providing, for each channel, a plurality of bandpass filters,... |
| 4438526 |
Automatic volume and frequency controlled sound masking system |
| Mar-20-1984 |
A sound masking system for generating background sound. The background sound is automatically adjusted to ambient noise levels by adjusting the amplitude of the frequency levels detected. |
| 4160875 |
Security system |
| Jul-10-1979 |
A security system for use in homes, hotels, businesses, schools, streets, and other locations requiring a high degree of security but where it is important to insure the privacy of the protected individual. |
| 4133977 |
Voice scrambler using syllabic masking |
| Jan-9-1979 |
Voice signals are combined with a masking signal that changes frequencies between discrete frequencies at a selected rate and in a random manner. The combined voice spectrum and masking signal is frequency... |
| 3985958 |
Secret telephony |
| Oct-12-1976 |
1. In secret telephony, means to analyze speech message waves into slowly varying currents representative of energy variations in respective portions of the speech frequency band, distributor means for... |
| 3978288 |
Method and apparatus for the secret transmission of speech signals |
| Aug-31-1976 |
Method and apparatus for enhancing the secret (confidential) transmission of voice (speech) type signals. The voice signals are encoded at a transmitter facility. Filling signals are inserted into breaks... |
