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Publication numberUS3004104 A
Publication typeGrant
Publication dateOct 10, 1961
Filing dateApr 29, 1954
Priority dateApr 29, 1954
Publication numberUS 3004104 A, US 3004104A, US-A-3004104, US3004104 A, US3004104A
InventorsHembrooke Emil Frank
Original AssigneeMuzak Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Identification of sound and like signals
US 3004104 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

Oct. 10, 1961 E. F. HEMBROOKE IDENTIFICATION OF SOUND AND LIKE SIGNALS Filed April 29, 1954 mnPC ESZ FREQUENCY f' looo IOO . E M T moat E24 LOUDSPEAKERW AMPLIFIER :PLAYBAOK' RECORD l l. l

' FILTER \NVENTOR Emil Fran/r, Hemraoie BY MWMf I! 7 ATTORNE q TRANSDUCER EILTER 3,004,104 IDENTIFICATION OF SOUND AND LIKE SIGNALS Emil Frank Hembrooke, Brooklyn, N.Y., assiguor to Muzak Corporation, New York,'N.Y., a corporation of New York Filed Apr. 29, 1954, Ser.'No. 426,465 6 Claims. (Cl. 1792) 'vides for the identification of recorded music or other audio signals by coded signals which are not evident to a listener but which nonetheless can easily be detected and which are such an integral part of the audio signals.

that they are difficult if not impossible to obliterate.

The unauthorized recording and rebroadcasting of musical performances, for example, has been difiicult to prevent because of the inability to detect positively whether the rebroadcast is an exact reproduction of the original or a different performance. tion makes possible the positive identification of the origin of a musical presentation and therebyconstitutes an effective means of preventing such piracy, ie it may be likened to a watermark in paper.

The invention may be used for the identification of any kind of signal, whether audio, or other, comprising a number of dilferent frequency components, although for purposes of illustration it is shown and described herein as applied to the identification of audio signals.

It is well known that a complex audio signal, such as music or speech, is composed of a number of frequency components extending over a wide range of frequencies.

In accordance with the present invention such a signal is identified by suppressing a selected frequency, or narrow band of frequencies, within the frequency spectrum of the signal at timed intervals accordingto apredeterimined code. Because of the insensitivity of the ear in detecting the absence of a particular frequency or narrow band of frequencies in a sound signal, the identifying code will be imperceptible to the listener.

The suppression of a selected frequency or narrow band of frequencies is accomplished, in a specific embodiment of the invention, by converting the signal into a complex electrical voltage and then passing this voltage through a very narrow band-reject electrical filter which passes all but a very narrow range of frequencies in the complex voltage.

In the accompanying drawings:

FIGURE 1 is a graph of the spectrum of frequencies in a typical sound signal at an instant of time when a predetermined narrow range of frequencies is being suppressed;

FIGURE 2 is a graph of the amplitude of the sound signals in said predetermined narrow range of frequencies, plotted versus time to portray an illustrative coding sequence;

FIGURE 3 is an electric circuit, in block form, for impressing an identifying code on a signal in accordance with one embodiment of this invention;

FIGURE 4 is an electric circuit, in block form, for detecting the identifying code.

In FIGURE 1 the horizontal scale represents the fre- The present invenquencies of the various components in a typical sound signal while the vertical scale represenst the amplitude of these various components at a particular instantof time. The audible frequency range of the sound signal, as indicated in this figure, extends approximately from 20 cycles per second to 20,000 cycles per second.

The amplitudes of frequency components of the signal over a very narrow range of frequency, for example, 10 cycles per second, at some place in the frequency spectrum are attenuated, in accordance with the invention,

in order to identify the signal. The attenuation of these.

for example, in the vicinity of 1000 cycles per second,

that can be accommodated in even the cheapest reproducing systems since the permanence as an identifying mark of the attenuated harmonic components when so placed is greater than if frequency i were placed at one edge of the signal frequency range. If it were placed at one edge, for example, at approximately 20,000 cycles per second, the identifying effect could be entirely eliminated simply by filtering out all of the very high frequencies of the sound signal. Moreover, in this regard, the frequency i should be placed at a frequency which is generally present in the signal to be identified. ,This frequency will of course depend upon the signal, but for music approximately 1000 cycles per second has been found to be satisfactory.

As shown in FIGURE 2, the identifying mark is discontinuous and eliminates the selected frequency components of the signal only at certain intervals of time, according to a predetermined, coded pattern.

FIGURE 3 shows a specific illustrative embodiment of a coding apparatus according to the invention comprising an electric circuit for impressing upon the signal to be marked a code of the type illustrated in FIG- URE 2. The audio signal voltage, comprising a number of frequency components extending over a wide range of frequency, is applied at input terminal 11. This voltage is switched by means of an encoding switch 12' either directly from terminal 11 to terminal 13 or through a band-reject filter 14 to terminal 13, depending upon whether the switch,12 is open or closed. The switch 12 is opened and closed in sequence according to a predetermined coding pattern, for example, the name of the orchestra or the trademark of the recording company may be spelled out in International Code, or any other suitably identifiable sequence of pulses may be utilized as a proprietary code. The encoding switch may be actuated mechanically, as by means of a coding cam, so that the coding equipment is fully automatic and may be employed continuously at very slight expense. The band-reject filter 14 preferably has a very high Q that is, it is sharply tuned to reject only the frequency components within an extremely narrow range on either side of its resonant frequency, 13,, so that the absence of the rejected frequency components will be imperceptible to the listener. This necessitates, of course, that the reduction in the total power of the audio signal due to the deletion of said selected frequency components be less than approximately 3 decibels.

The output voltage from terminal 13 may be broadcast concurrently or it may be recorded and reproduced at. a later time, as illustrated in FIGURE 3, by means of.

a playback head, amplifier and speaker.

The code impressed on the signal by switch 12 will serve to identify thereafter the origin of the audio signal so marked.

FIGURE 4 shows a specific illustrative embodiment Patented Oct. 10, 1961v of an apparatus for detecting the identifying code in the audio signal. This apparatus includes an input terminal 20 to which may be applied an audio signal voltage similar to that obtained at terminal 13 or terminal 13 in FIGURE 3. This voltage is amplified by means of an amplifier 21 and fed through a band pass filter 22, which has a transmission characteristic such that it will pass. only frequency components within the same narrow range of frequency which the band-reject filter 14 will reject, as previously described. In'other words, the transmission characteristics of the band-pass filter 22' are substantially opposite to those of the bandreject' filter '14. The output of the band-pass filter 22 is connected to a suitable transducer 23, such as a recording meter, oscilloscope, Or the like. As the voltage applied to terminal 20 passes through the filter 22, all frequency components of the signal lying outside the pass band are eliminated and only those within this band are passed. Since these frequencies were alternately suppressed and passed by the encoding circuit illustrated in FIGURE 3, the voltage applied to the transducer 23 will be intermittent. If transducer 23 is a recording meter containing a rectifier which converts these audio frequency alternating current voltages to direct current voltages, it can plot a graph oftheir amplitude versus time. Thus, a graph of the type illustrated in FIGURE 2 is plotted, in which the coding pattern, as indicated at 24 in FIG- URE 2, is readily apparent. Alternatively, transducer 23 may be a loudspeaker to convert the identifying code into sound.

The foregoing is intended in illustration and not in limitation. Changes or modifications inthe embodiments illustrated will occur to those skilled in the art and these changes or modifications may be made without departing from the spirit or scope of the invention as set foith.

' I claim:

1. In combination, an input terminal, means for supplying to said terminal an electric signal corresponding to an original signal and having a plurality of frequency components each having a respective frequency and amplitude, an output terminal, encoding means for impress ing a distinctive code on said electric signal for identifying the origin of said original signal, said encoding means including a narrow-band-reject filter adapted to attenuate said components of said electric signal within a very narrow frequency range, and also including a switch for connecting and for disconnecting said filter between said terminals in a predetermined time sequence to form said distinctive code.

2. A system of reproducing a continuous sound such as a musical selection and of permanently but unchtrusively identifying its origincomprising: means for continuously generating an electric signal corresponding to said sound and having frequency components extending substantially over the audio range of frequencies, means for variably attenuating in accordance with an identifying code frequency components of said signal lying within a very narrow band of frequency within said audio range, and means for then utilizing said identified electric-signal whereby either said sound substantially in original form without the audible presence of said code or said code alone can be reproduced.

3. The system as in claim 2 wherein said' means for utilizing includes means for eliminating all frequency components of said electric signal except those remaining in said narrow band. 1

4. The system as in'claim 2 wherein said narrow band of frequency has a width of only a few cycles per second, and is near the center of said band.

5. A method of unobtrusively identifying a sound signal such as a musical selection, said method'comprising the steps of taking a sound signal having frequency components within the audio range, and attenuating the components in a very narrow frequency band within said range in accordance with an identifying pattern so that said signal will be permanently marked with an easily detectable pattern but a person hearing said marked-- signal will be unaware of audible change in it.

6. The method as in claim 5 wherein said narrow frequency band has a width of the order of ten cycles per second and lies in said audio range near a frequency of one thousand cycles per second.

References Cited in the file of this patent UNITED STATES PATENTS 1,724,938 Jammer Aug. 20, 1929 2,116,172 Hyneman et al May 3,. 1938 2,335,335 Zenner Nov. 30, 1943 2,352,918 Smith July 4, 1944 2,376,275 Rhoads May 14, 1945 2,398,755 Shepherd Apr. 16, 1946- 2,406,034 Phelps Aug. 20, 1946 2,474,191 Reid et al. June 21, 1949 2,503,701 Baughman Apr. 11, 1950 2,580,973 Sueur Jan. '1, 1952 2,636,936 Goldsmith Apr. 28, 1953-

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1724938 *Nov 20, 1926Aug 20, 1929Western Electric CoCarrier-wave transmission
US2116172 *Dec 27, 1935May 3, 1938Western Union Telegraph CoComposite set
US2335335 *Jan 18, 1941Nov 30, 1943Teletype CorpCommunication system
US2352918 *Oct 30, 1942Jul 4, 1944Rca CorpTwo-way telephone and telegraph system
US2376275 *Mar 24, 1944May 15, 1945American Telephone & TelegraphSignaling system
US2398755 *Jun 17, 1943Apr 16, 1946O'd Shepherd JudsonCommunication system
US2406034 *Aug 24, 1943Aug 20, 1946Bell Telephone Labor IncCarrier wave signaling system
US2474191 *Jun 6, 1947Jun 21, 1949Avco Mfg CorpTone control
US2503701 *Nov 26, 1946Apr 11, 1950Union Switch & Signal CoSimplexed line circuit system for remote-control systems
US2580973 *Aug 7, 1947Jan 1, 1952Rene SueurPulse signaling means
US2636936 *Sep 10, 1946Apr 28, 1953Rca CorpTelevision secrecy system
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3210864 *Dec 6, 1962Oct 12, 1965Meyer Jerome CElectronic device and method for testing and teaching
US3360873 *Oct 1, 1965Jan 2, 1968James A. TillotsonElectronic device and method for testing and teaching
US3639839 *Sep 16, 1969Feb 1, 1972Masayuki FukataBroadcast system for a control signal
US3735048 *May 28, 1971May 22, 1973Motorola IncIn-band data transmission system
US3969675 *Dec 30, 1974Jul 13, 1976National Research Development CorporationSingle side-band radio
US4644422 *Jun 24, 1983Feb 17, 1987Tvi Systems, Ltd.Anti-copy system
US4663674 *Jan 22, 1986May 5, 1987Sony CorporationVideo cassette designed for video theater use
US4739398 *May 2, 1986Apr 19, 1988Control Data CorporationMethod, apparatus and system for recognizing broadcast segments
US5319735 *Dec 17, 1991Jun 7, 1994Bolt Beranek And Newman Inc.Embedded signalling
US5394274 *Apr 13, 1993Feb 28, 1995Kahn; Leonard R.Anti-copy system utilizing audible and inaudible protection signals
US5450490 *Mar 31, 1994Sep 12, 1995The Arbitron CompanyApparatus and methods for including codes in audio signals and decoding
US5574962 *Dec 20, 1994Nov 12, 1996The Arbitron CompanyMethod and apparatus for automatically identifying a program including a sound signal
US5579124 *Feb 28, 1995Nov 26, 1996The Arbitron CompanyMethod and apparatus for encoding/decoding broadcast or recorded segments and monitoring audience exposure thereto
US5581800 *Jun 7, 1995Dec 3, 1996The Arbitron CompanyMethod and apparatus for automatically identifying a program including a sound signal
US5764763 *Mar 24, 1995Jun 9, 1998Jensen; James M.Apparatus and methods for including codes in audio signals and decoding
US5787334 *Sep 27, 1996Jul 28, 1998Ceridian CorporationPersonal monitoring device
US6289108 *Feb 10, 2000Sep 11, 2001Digimarc CorporationMethods for detecting alteration of audio and images
US6363159Nov 17, 1999Mar 26, 2002Digimarc CorporationConsumer audio appliance responsive to watermark data
US6400827Jun 29, 1999Jun 4, 2002Digimarc CorporationMethods for hiding in-band digital data in images and video
US6404898Jun 24, 1999Jun 11, 2002Digimarc CorporationMethod and system for encoding image and audio content
US6430302Jan 10, 2001Aug 6, 2002Digimarc CorporationSteganographically encoding a first image in accordance with a second image
US6496591Jun 29, 1999Dec 17, 2002Digimarc CorporationVideo copy-control with plural embedded signals
US6539095Nov 17, 1999Mar 25, 2003Geoffrey B. RhoadsAudio watermarking to convey auxiliary control information, and media embodying same
US6542620 *Jul 27, 2000Apr 1, 2003Digimarc CorporationSignal processing to hide plural-bit information in image, video, and audio data
US6560349 *Dec 28, 1999May 6, 2003Digimarc CorporationAudio monitoring using steganographic information
US6560350 *Jun 29, 2001May 6, 2003Digimarc CorporationMethods for detecting alteration of audio
US6567780Apr 9, 2002May 20, 2003Digimarc CorporationAudio with hidden in-band digital data
US6631165Sep 1, 1999Oct 7, 2003Northrop Grumman CorporationCode modulation using narrow spectral notching
US6654480Mar 25, 2002Nov 25, 2003Digimarc CorporationAudio appliance and monitoring device responsive to watermark data
US6675146May 31, 2001Jan 6, 2004Digimarc CorporationAudio steganography
US6738491 *Aug 14, 1997May 18, 2004Minolta Co., Ltd.Image forming apparatus and copy management system
US6754377Jun 6, 2002Jun 22, 2004Digimarc CorporationMethods and systems for marking printed documents
US6757300Jun 4, 1999Jun 29, 2004Innes Corporation Pty LtdTraffic verification system
US6871180May 25, 1999Mar 22, 2005Arbitron Inc.Decoding of information in audio signals
US6879652Jul 14, 2000Apr 12, 2005Nielsen Media Research, Inc.Method for encoding an input signal
US6944298May 31, 2000Sep 13, 2005Digimare CorporationSteganographic encoding and decoding of auxiliary codes in media signals
US6968564Apr 6, 2000Nov 22, 2005Nielsen Media Research, Inc.Multi-band spectral audio encoding
US6987862Jul 11, 2003Jan 17, 2006Digimarc CorporationVideo steganography
US6996237Jul 12, 2002Feb 7, 2006Arbitron Inc.Apparatus and methods for including codes in audio signals
US7003132Apr 1, 2003Feb 21, 2006Digimarc CorporationEmbedding hidden auxiliary code signals in media
US7006555Oct 27, 1999Feb 28, 2006Nielsen Media Research, Inc.Spectral audio encoding
US7181022Mar 25, 2003Feb 20, 2007Digimarc CorporationAudio watermarking to convey auxiliary information, and media embodying same
US7184570 *May 27, 2004Feb 27, 2007Digimarc CorporationMethods and systems for steganographic processing
US7266215Feb 21, 2002Sep 4, 2007Minolta Co., Ltd.Image forming apparatus and copy management system
US7333957 *Jan 6, 2003Feb 19, 2008Digimarc CorporationConnected audio and other media objects
US7362781Aug 7, 2001Apr 22, 2008Digimarc CorporationWireless methods and devices employing steganography
US7388965Dec 5, 2003Jun 17, 2008Minolta Co., Ltd.Imaging forming apparatus and copy management system
US7451092Mar 5, 2004Nov 11, 2008Nielsen Media Research, Inc. A Delaware CorporationDetection of signal modifications in audio streams with embedded code
US7463752Apr 12, 2007Dec 9, 2008Konica Minolta Business Technologies, Inc.Imaging forming apparatus and copy management system
US7466742Apr 21, 2000Dec 16, 2008Nielsen Media Research, Inc.Detection of entropy in connection with audio signals
US7505605Apr 13, 2004Mar 17, 2009Digimarc CorporationPortable devices and methods employing digital watermarking
US7522728 *Jan 6, 2000Apr 21, 2009Digimarc CorporationWireless methods and devices employing steganography
US7536555Jan 3, 2006May 19, 2009Digimarc CorporationMethods for audio watermarking and decoding
US7562392Dec 30, 1999Jul 14, 2009Digimarc CorporationMethods of interacting with audio and ambient music
US7567686Oct 25, 2005Jul 28, 2009Digimarc CorporationHiding and detecting messages in media signals
US7672477Sep 9, 2008Mar 2, 2010Digimarc CorporationDetecting hidden auxiliary code signals in media
US7672843Jun 2, 2005Mar 2, 2010The Nielsen Company (Us), LlcAudio signature extraction and correlation
US7715446Feb 2, 2007May 11, 2010Digimarc CorporationWireless methods and devices employing plural-bit data derived from audio information
US7724919Feb 23, 2007May 25, 2010Digimarc CorporationMethods and systems for steganographic processing
US7751588Dec 16, 2008Jul 6, 2010Digimarc CorporationError processing of steganographic message signals
US7756290May 6, 2008Jul 13, 2010Digimarc CorporationDetecting embedded signals in media content using coincidence metrics
US7945781Mar 30, 2000May 17, 2011Digimarc CorporationMethod and systems for inserting watermarks in digital signals
US7961881Nov 4, 2005Jun 14, 2011Arbitron Inc.Apparatus and methods for including codes in audio signals
US7961949Oct 12, 2009Jun 14, 2011Digimarc CorporationExtracting multiple identifiers from audio and video content
US7974439Sep 15, 2009Jul 5, 2011Digimarc CorporationEmbedding hidden auxiliary information in media
US7987094Feb 20, 2007Jul 26, 2011Digimarc CorporationAudio encoding to convey auxiliary information, and decoding of same
US7987245Nov 26, 2008Jul 26, 2011Digimarc CorporationInternet linking from audio
US7992003Jul 19, 2006Aug 2, 2011Digimarc CorporationMethods and systems for inserting watermarks in digital signals
US8014563May 25, 2010Sep 6, 2011Digimarc CorporationMethods and systems for steganographic processing
US8027510Jul 13, 2010Sep 27, 2011Digimarc CorporationEncoding and decoding media signals
US8027663Oct 19, 2007Sep 27, 2011Digimarc CorporationWireless methods and devices employing steganography
US8051294May 19, 2009Nov 1, 2011Digimarc CorporationMethods for audio watermarking and decoding
US8055012Jul 28, 2009Nov 8, 2011Digimarc CorporationHiding and detecting messages in media signals
US8184849Jul 6, 2010May 22, 2012Digimarc CorporationError processing of steganographic message signals
US8184851Apr 12, 2011May 22, 2012Digimarc CorporationInserting watermarks into portions of digital signals
US8190713Jul 21, 2011May 29, 2012Digimarc CorporationControlling a device based upon steganographically encoded data
US8204222Sep 13, 2005Jun 19, 2012Digimarc CorporationSteganographic encoding and decoding of auxiliary codes in media signals
US8244527Jan 4, 2010Aug 14, 2012The Nielsen Company (Us), LlcAudio signature extraction and correlation
US8355514Oct 26, 2007Jan 15, 2013Digimarc CorporationAudio encoding to convey auxiliary information, and media embodying same
US8369363May 11, 2010Feb 5, 2013Digimarc CorporationWireless methods and devices employing plural-bit data derived from audio information
US8369972 *Oct 10, 2008Feb 5, 2013The Nielsen Company (Us), LlcMethods and apparatus to perform audio watermarking and watermark detection and extraction
US8457951Jan 29, 2009Jun 4, 2013The Nielsen Company (Us), LlcMethods and apparatus for performing variable black length watermarking of media
US8521850Jul 21, 2011Aug 27, 2013Digimarc CorporationContent containing a steganographically encoded process identifier
US20090259325 *Oct 10, 2008Oct 15, 2009Alexander Pavlovich TopchyMethods and apparatus to perform audio watermarking and watermark detection and extraction
USRE42627Mar 22, 2007Aug 16, 2011Arbitron, Inc.Encoding and decoding of information in audio signals
EP1978658A2Mar 27, 1995Oct 8, 2008THE ARBITRON COMPANY, a division of CERIDIAN CORPORATIONApparatus and methods for including codes in audio signals and decoding
WO1992005550A1 *Sep 14, 1990Mar 15, 1992James DaleEncoding system
WO2010121178A1Apr 16, 2010Oct 21, 2010Arbitron, Inc.System and method for determining broadcast dimensionality
Classifications
U.S. Classification341/182, 455/39, 369/47.26, 381/98, 360/60, G9B/20.2, 360/22, 360/15
International ClassificationG01H3/00, G11B20/00
Cooperative ClassificationG01H3/00, G11B20/00891, G11B20/00086
European ClassificationG01H3/00, G11B20/00P14A, G11B20/00P