GB2063018A - Telecommunication system - Google Patents

Telecommunication system Download PDF

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Publication number
GB2063018A
GB2063018A GB8032512A GB8032512A GB2063018A GB 2063018 A GB2063018 A GB 2063018A GB 8032512 A GB8032512 A GB 8032512A GB 8032512 A GB8032512 A GB 8032512A GB 2063018 A GB2063018 A GB 2063018A
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GB
United Kingdom
Prior art keywords
speech
data
bit
transmission
sample
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8032512A
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GB2063018B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co PLC
Original Assignee
General Electric Co PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by General Electric Co PLC filed Critical General Electric Co PLC
Priority to GB8032512A priority Critical patent/GB2063018B/en
Publication of GB2063018A publication Critical patent/GB2063018A/en
Application granted granted Critical
Publication of GB2063018B publication Critical patent/GB2063018B/en
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
    • H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/12—Arrangements providing for calling or supervisory signals
    • H04J3/125—One of the channel pulses or the synchronisation pulse is also used for transmitting monitoring or supervisory signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
    • H04M11/06—Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors
    • H04M11/064—Data transmission during pauses in telephone conversation

Abstract

In a telecommunication system in which speech signals are sampled and the sample values digitally encoded for transmission, there are provided means selectively to replace the least significant digits of a sequence of coded samples by a sequence of data digits, whereby the data digits may be transmitted with the encoded speech signals.

Description

SPECIFICATION Telecommunication systems The present invention relates to a transmission of data over a digital speech transmission path.
In a telecommunication system in which speech is coded in digital form for transmission within the system, it is a relatively simple matter to multiplex other digital signals such as data signals with the coded speech signals to provide a number of services within the system either related to or independent of the speech channels. Typical services would include viewdata, telewriter, facsimile, metering and alarms. Provision may also be made for signals controlling the transmission network and for directing the various services to the correct destinations.
One area in which such speech and data multiplexing would be particularly useful is the subscribers' network, that is the part of the transmission system between an exchange and its subscribers, since it would enable a subscriber to use data services while holding a normal telephone conversation.
The multiplexing can be achieved by replacing the least significant bit of every eight-bit coded speech sample by a data or a signalling bit, a technique known as "bit-stealing", which allows the data or signalling information to be transmitted with the coded speech at the expense of speech quality.
Generally the reduction in quality is not significant subjectively, but on circuits where distortion is present, acceptable standards of speech quality may not be attained.
According to the present invention in a telecommunications system in which each of a succession of samples of a speech signal to be transmitted over the system is digitaily encoded for transmission there are provided means selectively to replace a digit of a coded speech sample by a data digit whereby data signals may be transmitted with said speech signals.
Preferably said means operates in dependence upon the value of a control signal to replace the least significant digit of a coded speech sample by a data digit. The means may comprise two registers between which the digits of a coded speech sample may be transferred in parallel selectively with or without the replacement of the least significant digit, which may be effected by gating means between the respective stages of the two registers.
Atelecommunications system in accordance with the present invention will now be described by way of example with reference to the accompanying drawing, which shows part of the system schematically.
In the telecommunication system, which may include a conventional telephone system, speech signals to be transmitted over at least some of the transmission paths of the system are sampled periodically and the amplitude of each sample is digitally encoded for transmission, for example in eight-bit compression law format. At any point in the transmission path of the encoded samples there may be provided an arrangement as shown in the drawing, by means of which digital data signals at an input 11 may be multiplexed with encoded speech signals for transmission with those speech signals.
The arrangement comprises a register 12 into which the eight bits of an encoded sample may be entered serially and from which these bits may be transferred in parallel to another register 13.
The least significant bit of the encoded sample is transferred by way of one of a pair of AND gates 14 one or other of which is enabled by means of a control signal from an input 15, or its inverse, to pass the least significant bit or a data bit to an OR gate 16.
The least significant bit stage of the register 13 thereby receives either a speech bit or a data bit, and in the latter case successive eight-bit bytes representing successive encoded samples may carry a predetermined succession of data bits forming a headerorframing code to enable the receiving end and demultiplexer to detect that data bits and not speech bits are present.
The eight bits from the register 13 may be read out serially, preceded by a marker bit and a signalling bit, and followed by one or more data bits which may subsequently be routed separately from the eight bits of the multiplexed sample.
When no data is present the full encoded speech sample is transmitted. In practice, even when data is present, in many instances the ratio of simultaneous data to simultaneous speech is very low, so that full speech standards are maintained for a very high percentage of the time. This situation arises because of the following points: 1) digital speech bit rates are much higherthan many data services so that the ratio of data/ speech bits is low, 2) natural breaks occur in speaking, 3) for many subscriber services, the transmitted data is only intermittent, 4) breaks in both speaking and data transmission occur to allow reception from the other end and these breaks would generally be unsynchro nised.
1. A telecommunications system in which each of a succession of samples of a speech signal to be transmitted over the system is digitally encoded for transmission wherein there are provided means selectively to replace a digit of a coded speech sample by a data digit whereby data signals may be transmitted with said speech signals.
2. A telecommunications system in accordance with Claim 1 wherein said means operates in dependence upon the value of a control signal to replace the least significant digit of a coded speech sample by a data digit.
3. Atelecommunication system in accordance with Claim 1 or Claim 2 wherein said means comprises two registers between which the digits of a coded speech sample are arranged to be transferred in parallel selectively with or without the replacement of the least significant digit.
4. Atelecommunication system in accordance with Claim 3 wherein the selective replacement of the least significant digit is effected by gating means
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Telecommunication systems The present invention relates to a transmission of data over a digital speech transmission path. In a telecommunication system in which speech is coded in digital form for transmission within the system, it is a relatively simple matter to multiplex other digital signals such as data signals with the coded speech signals to provide a number of services within the system either related to or independent of the speech channels. Typical services would include viewdata, telewriter, facsimile, metering and alarms. Provision may also be made for signals controlling the transmission network and for directing the various services to the correct destinations. One area in which such speech and data multiplexing would be particularly useful is the subscribers' network, that is the part of the transmission system between an exchange and its subscribers, since it would enable a subscriber to use data services while holding a normal telephone conversation. The multiplexing can be achieved by replacing the least significant bit of every eight-bit coded speech sample by a data or a signalling bit, a technique known as "bit-stealing", which allows the data or signalling information to be transmitted with the coded speech at the expense of speech quality. Generally the reduction in quality is not significant subjectively, but on circuits where distortion is present, acceptable standards of speech quality may not be attained. According to the present invention in a telecommunications system in which each of a succession of samples of a speech signal to be transmitted over the system is digitaily encoded for transmission there are provided means selectively to replace a digit of a coded speech sample by a data digit whereby data signals may be transmitted with said speech signals. Preferably said means operates in dependence upon the value of a control signal to replace the least significant digit of a coded speech sample by a data digit. The means may comprise two registers between which the digits of a coded speech sample may be transferred in parallel selectively with or without the replacement of the least significant digit, which may be effected by gating means between the respective stages of the two registers. Atelecommunications system in accordance with the present invention will now be described by way of example with reference to the accompanying drawing, which shows part of the system schematically. In the telecommunication system, which may include a conventional telephone system, speech signals to be transmitted over at least some of the transmission paths of the system are sampled periodically and the amplitude of each sample is digitally encoded for transmission, for example in eight-bit compression law format. At any point in the transmission path of the encoded samples there may be provided an arrangement as shown in the drawing, by means of which digital data signals at an input 11 may be multiplexed with encoded speech signals for transmission with those speech signals. The arrangement comprises a register 12 into which the eight bits of an encoded sample may be entered serially and from which these bits may be transferred in parallel to another register 13. The least significant bit of the encoded sample is transferred by way of one of a pair of AND gates 14 one or other of which is enabled by means of a control signal from an input 15, or its inverse, to pass the least significant bit or a data bit to an OR gate 16. The least significant bit stage of the register 13 thereby receives either a speech bit or a data bit, and in the latter case successive eight-bit bytes representing successive encoded samples may carry a predetermined succession of data bits forming a headerorframing code to enable the receiving end and demultiplexer to detect that data bits and not speech bits are present. The eight bits from the register 13 may be read out serially, preceded by a marker bit and a signalling bit, and followed by one or more data bits which may subsequently be routed separately from the eight bits of the multiplexed sample. When no data is present the full encoded speech sample is transmitted. In practice, even when data is present, in many instances the ratio of simultaneous data to simultaneous speech is very low, so that full speech standards are maintained for a very high percentage of the time. This situation arises because of the following points: 1) digital speech bit rates are much higherthan many data services so that the ratio of data/ speech bits is low, 2) natural breaks occur in speaking, 3) for many subscriber services, the transmitted data is only intermittent, 4) breaks in both speaking and data transmission occur to allow reception from the other end and these breaks would generally be unsynchro nised. CLAIMS
1. A telecommunications system in which each of a succession of samples of a speech signal to be transmitted over the system is digitally encoded for transmission wherein there are provided means selectively to replace a digit of a coded speech sample by a data digit whereby data signals may be transmitted with said speech signals.
2. A telecommunications system in accordance with Claim 1 wherein said means operates in dependence upon the value of a control signal to replace the least significant digit of a coded speech sample by a data digit.
3. Atelecommunication system in accordance with Claim 1 or Claim 2 wherein said means comprises two registers between which the digits of a coded speech sample are arranged to be transferred in parallel selectively with or without the replacement of the least significant digit.
4. Atelecommunication system in accordance with Claim 3 wherein the selective replacement of the least significant digit is effected by gating means between the respective stages of the two registers.
5. Atelecommunication system substantially as hereinbefore described with reference to the accompanying drawing.
GB8032512A 1979-10-08 1980-10-08 Telecommunication systems Expired GB2063018B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8032512A GB2063018B (en) 1979-10-08 1980-10-08 Telecommunication systems

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB7934908 1979-10-08
GB8032512A GB2063018B (en) 1979-10-08 1980-10-08 Telecommunication systems

Publications (2)

Publication Number Publication Date
GB2063018A true GB2063018A (en) 1981-05-28
GB2063018B GB2063018B (en) 1984-03-28

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Cited By (31)

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Publication number Priority date Publication date Assignee Title
EP0058482A1 (en) * 1981-02-16 1982-08-25 British Telecommunications Method and apparatus for transmitting data with digitally encoded speech
FR2516326A1 (en) * 1981-11-09 1983-05-13 Western Electric Co METHOD AND DEVICE FOR SIMULTANEOUSLY TRANSMITTING VOICE SIGNALS AND DATA SIGNALS ON A DIGITAL PATH
US4516241A (en) * 1983-07-11 1985-05-07 At&T Bell Laboratories Bit compression coding with embedded signaling
US4520477A (en) * 1983-06-27 1985-05-28 At&T Bell Laboratories Control information communication arrangement for a time division switching system
EP0145332A2 (en) * 1983-11-18 1985-06-19 BRITISH TELECOMMUNICATIONS public limited company Digital audio transmission
GB2175772A (en) * 1985-06-01 1986-12-03 Roger Paul Haywood Transmission of interviews
EP0205200A1 (en) * 1985-05-21 1986-12-17 POLYGRAM GmbH Method for transmitting audio and additional information in digital form
WO1987005173A1 (en) * 1986-02-21 1987-08-27 San/Bar Corporation Voice, data or both over one telephone line in a t-1 carrier system
GB2187364A (en) * 1986-02-26 1987-09-03 Sony Corp Methods of and apparatus for coding digital data
EP0359325A1 (en) * 1988-09-16 1990-03-21 Koninklijke Philips Electronics N.V. Device for transmitting data words representing a digitized analog signal and device for receiving the transmitted data words
GB2268358A (en) * 1989-12-04 1994-01-05 Academy Of Applied Sciences Telephone link multiplex channelling of voice and data
GB2316272A (en) * 1996-08-09 1998-02-18 Motorola Ltd Method of local call routing and transcoder for use in the method
US6301369B2 (en) 1992-07-31 2001-10-09 Digimarc Corporation Image marking to permit later identification
US6317505B1 (en) 1992-07-31 2001-11-13 Digimarc Corporation Image marking with error correction
US6343138B1 (en) 1993-11-18 2002-01-29 Digimarc Corporation Security documents with hidden digital data
US6430302B2 (en) 1993-11-18 2002-08-06 Digimarc Corporation Steganographically encoding a first image in accordance with a second image
WO2002091361A1 (en) * 2001-05-08 2002-11-14 Dolby Laboratories Licensing Corporation Adding data to a compressed data frame
US6542620B1 (en) 1993-11-18 2003-04-01 Digimarc Corporation Signal processing to hide plural-bit information in image, video, and audio data
US6560349B1 (en) 1994-10-21 2003-05-06 Digimarc Corporation Audio monitoring using steganographic information
US6751320B2 (en) 1996-04-25 2004-06-15 Digimarc Corporation Method and system for preventing reproduction of professional photographs
US6757406B2 (en) 1993-11-18 2004-06-29 Digimarc Corporation Steganographic image processing
US6775392B1 (en) 1995-07-27 2004-08-10 Digimarc Corporation Computer system linked by using information in data objects
US7742737B2 (en) 2002-01-08 2010-06-22 The Nielsen Company (Us), Llc. Methods and apparatus for identifying a digital audio signal
US7744001B2 (en) 2001-12-18 2010-06-29 L-1 Secure Credentialing, Inc. Multiple image security features for identification documents and methods of making same
US7779271B2 (en) 2001-11-23 2010-08-17 Civolution B.V. Watermark embedding
US7798413B2 (en) 2001-12-24 2010-09-21 L-1 Secure Credentialing, Inc. Covert variable information on ID documents and methods of making same
US7804982B2 (en) 2002-11-26 2010-09-28 L-1 Secure Credentialing, Inc. Systems and methods for managing and detecting fraud in image databases used with identification documents
US7824029B2 (en) 2002-05-10 2010-11-02 L-1 Secure Credentialing, Inc. Identification card printer-assembler for over the counter card issuing
US7963449B2 (en) 2004-03-11 2011-06-21 L-1 Secure Credentialing Tamper evident adhesive and identification document including same
US7980596B2 (en) 2001-12-24 2011-07-19 L-1 Secure Credentialing, Inc. Increasing thermal conductivity of host polymer used with laser engraving methods and compositions
US9900633B2 (en) 2002-10-23 2018-02-20 The Nielsen Company (Us), Llc Digital data insertion apparatus and methods for use with compressed audio/video data

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US6611607B1 (en) 1993-11-18 2003-08-26 Digimarc Corporation Integrating digital watermarks in multimedia content
US5636292C1 (en) 1995-05-08 2002-06-18 Digimarc Corp Steganography methods employing embedded calibration data
US5841886A (en) 1993-11-18 1998-11-24 Digimarc Corporation Security system for photographic identification
US5832119C1 (en) 1993-11-18 2002-03-05 Digimarc Corp Methods for controlling systems using control signals embedded in empirical data
US6424725B1 (en) 1996-05-16 2002-07-23 Digimarc Corporation Determining transformations of media signals with embedded code signals
US5748783A (en) 1995-05-08 1998-05-05 Digimarc Corporation Method and apparatus for robust information coding
US7171016B1 (en) 1993-11-18 2007-01-30 Digimarc Corporation Method for monitoring internet dissemination of image, video and/or audio files
US5841978A (en) 1993-11-18 1998-11-24 Digimarc Corporation Network linking method using steganographically embedded data objects
US5710834A (en) 1995-05-08 1998-01-20 Digimarc Corporation Method and apparatus responsive to a code signal conveyed through a graphic image
US6408082B1 (en) 1996-04-25 2002-06-18 Digimarc Corporation Watermark detection using a fourier mellin transform
US6614914B1 (en) 1995-05-08 2003-09-02 Digimarc Corporation Watermark embedder and reader
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US6580819B1 (en) 1993-11-18 2003-06-17 Digimarc Corporation Methods of producing security documents having digitally encoded data and documents employing same
US6516079B1 (en) 2000-02-14 2003-02-04 Digimarc Corporation Digital watermark screening and detecting strategies
US6522770B1 (en) 1999-05-19 2003-02-18 Digimarc Corporation Management of documents and other objects using optical devices
US6728390B2 (en) 1995-05-08 2004-04-27 Digimarc Corporation Methods and systems using multiple watermarks
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US7224819B2 (en) 1995-05-08 2007-05-29 Digimarc Corporation Integrating digital watermarks in multimedia content
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US6577746B1 (en) 1999-12-28 2003-06-10 Digimarc Corporation Watermark-based object linking and embedding
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0058482A1 (en) * 1981-02-16 1982-08-25 British Telecommunications Method and apparatus for transmitting data with digitally encoded speech
FR2516326A1 (en) * 1981-11-09 1983-05-13 Western Electric Co METHOD AND DEVICE FOR SIMULTANEOUSLY TRANSMITTING VOICE SIGNALS AND DATA SIGNALS ON A DIGITAL PATH
US4520477A (en) * 1983-06-27 1985-05-28 At&T Bell Laboratories Control information communication arrangement for a time division switching system
US4516241A (en) * 1983-07-11 1985-05-07 At&T Bell Laboratories Bit compression coding with embedded signaling
US4703480A (en) * 1983-11-18 1987-10-27 British Telecommunications Plc Digital audio transmission
EP0145332A2 (en) * 1983-11-18 1985-06-19 BRITISH TELECOMMUNICATIONS public limited company Digital audio transmission
EP0145332A3 (en) * 1983-11-18 1985-07-17 British Telecommunications Plc Digital audio transmission
EP0205200A1 (en) * 1985-05-21 1986-12-17 POLYGRAM GmbH Method for transmitting audio and additional information in digital form
US4750173A (en) * 1985-05-21 1988-06-07 Polygram International Holding B.V. Method of transmitting audio information and additional information in digital form
GB2175772A (en) * 1985-06-01 1986-12-03 Roger Paul Haywood Transmission of interviews
US4730312A (en) * 1986-02-21 1988-03-08 San/Bar Corporation Voice, data or both over one telephone line in a T-1 carrier system
WO1987005173A1 (en) * 1986-02-21 1987-08-27 San/Bar Corporation Voice, data or both over one telephone line in a t-1 carrier system
GB2187364A (en) * 1986-02-26 1987-09-03 Sony Corp Methods of and apparatus for coding digital data
GB2187364B (en) * 1986-02-26 1989-10-25 Sony Corp Methods of and apparatus for coding digital data
EP0545915A3 (en) * 1988-09-16 1993-07-14 Koninkl Philips Electronics Nv Device for transmitting data words representing a digitized analog signal
EP0545915A2 (en) * 1988-09-16 1993-06-09 Koninklijke Philips Electronics N.V. Device for transmitting data words representing a digitized analog signal
EP0359325A1 (en) * 1988-09-16 1990-03-21 Koninklijke Philips Electronics N.V. Device for transmitting data words representing a digitized analog signal and device for receiving the transmitted data words
GB2268358A (en) * 1989-12-04 1994-01-05 Academy Of Applied Sciences Telephone link multiplex channelling of voice and data
GB2268358B (en) * 1989-12-04 1995-09-06 Academy Of Applied Sciences Telephone link multiplex channelling
US7978876B2 (en) 1992-07-31 2011-07-12 Digimarc Corporation Hiding codes in input data
US6628801B2 (en) 1992-07-31 2003-09-30 Digimarc Corporation Image marking with pixel modification
US6459803B1 (en) 1992-07-31 2002-10-01 Digimarc Corporation Method for encoding auxiliary data within a source signal
US6317505B1 (en) 1992-07-31 2001-11-13 Digimarc Corporation Image marking with error correction
US6301369B2 (en) 1992-07-31 2001-10-09 Digimarc Corporation Image marking to permit later identification
US6404898B1 (en) 1993-11-18 2002-06-11 Digimarc Corporation Method and system for encoding image and audio content
US6542620B1 (en) 1993-11-18 2003-04-01 Digimarc Corporation Signal processing to hide plural-bit information in image, video, and audio data
US6363159B1 (en) 1993-11-18 2002-03-26 Digimarc Corporation Consumer audio appliance responsive to watermark data
US6400827B1 (en) 1993-11-18 2002-06-04 Digimarc Corporation Methods for hiding in-band digital data in images and video
US6675146B2 (en) 1993-11-18 2004-01-06 Digimarc Corporation Audio steganography
US6430302B2 (en) 1993-11-18 2002-08-06 Digimarc Corporation Steganographically encoding a first image in accordance with a second image
US6757406B2 (en) 1993-11-18 2004-06-29 Digimarc Corporation Steganographic image processing
US6343138B1 (en) 1993-11-18 2002-01-29 Digimarc Corporation Security documents with hidden digital data
US6496591B1 (en) 1993-11-18 2002-12-17 Digimarc Corporation Video copy-control with plural embedded signals
US6539095B1 (en) 1993-11-18 2003-03-25 Geoffrey B. Rhoads Audio watermarking to convey auxiliary control information, and media embodying same
US6654480B2 (en) 1993-11-18 2003-11-25 Digimarc Corporation Audio appliance and monitoring device responsive to watermark data
US6587821B1 (en) 1993-11-18 2003-07-01 Digimarc Corp Methods for decoding watermark data from audio, and controlling audio devices in accordance therewith
US6567780B2 (en) 1993-11-18 2003-05-20 Digimarc Corporation Audio with hidden in-band digital data
US6560349B1 (en) 1994-10-21 2003-05-06 Digimarc Corporation Audio monitoring using steganographic information
US6775392B1 (en) 1995-07-27 2004-08-10 Digimarc Corporation Computer system linked by using information in data objects
US6751320B2 (en) 1996-04-25 2004-06-15 Digimarc Corporation Method and system for preventing reproduction of professional photographs
FR2752499A1 (en) * 1996-08-09 1998-02-20 Motorola Ltd LOCAL ROUTING PROCESS AND APPROPRIATE TRANSCODER THEREOF
GB2316272A (en) * 1996-08-09 1998-02-18 Motorola Ltd Method of local call routing and transcoder for use in the method
US5930715A (en) * 1996-08-09 1999-07-27 Motorola, Inc. Method of local routing and transcoder therefor
GB2316272B (en) * 1996-08-09 2000-12-27 Motorola Ltd Method of local routing and transcoder therefor
US6807528B1 (en) 2001-05-08 2004-10-19 Dolby Laboratories Licensing Corporation Adding data to a compressed data frame
WO2002091361A1 (en) * 2001-05-08 2002-11-14 Dolby Laboratories Licensing Corporation Adding data to a compressed data frame
US7779271B2 (en) 2001-11-23 2010-08-17 Civolution B.V. Watermark embedding
US7744001B2 (en) 2001-12-18 2010-06-29 L-1 Secure Credentialing, Inc. Multiple image security features for identification documents and methods of making same
US8025239B2 (en) 2001-12-18 2011-09-27 L-1 Secure Credentialing, Inc. Multiple image security features for identification documents and methods of making same
US7798413B2 (en) 2001-12-24 2010-09-21 L-1 Secure Credentialing, Inc. Covert variable information on ID documents and methods of making same
US7980596B2 (en) 2001-12-24 2011-07-19 L-1 Secure Credentialing, Inc. Increasing thermal conductivity of host polymer used with laser engraving methods and compositions
US7742737B2 (en) 2002-01-08 2010-06-22 The Nielsen Company (Us), Llc. Methods and apparatus for identifying a digital audio signal
US7824029B2 (en) 2002-05-10 2010-11-02 L-1 Secure Credentialing, Inc. Identification card printer-assembler for over the counter card issuing
US9900633B2 (en) 2002-10-23 2018-02-20 The Nielsen Company (Us), Llc Digital data insertion apparatus and methods for use with compressed audio/video data
US10681399B2 (en) 2002-10-23 2020-06-09 The Nielsen Company (Us), Llc Digital data insertion apparatus and methods for use with compressed audio/video data
US11223858B2 (en) 2002-10-23 2022-01-11 The Nielsen Company (Us), Llc Digital data insertion apparatus and methods for use with compressed audio/video data
US7804982B2 (en) 2002-11-26 2010-09-28 L-1 Secure Credentialing, Inc. Systems and methods for managing and detecting fraud in image databases used with identification documents
US7963449B2 (en) 2004-03-11 2011-06-21 L-1 Secure Credentialing Tamper evident adhesive and identification document including same

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