US3480737A - Apparatus for reducing time duration of signal reproduction - Google Patents

Apparatus for reducing time duration of signal reproduction Download PDF

Info

Publication number
US3480737A
US3480737A US532643A US3480737DA US3480737A US 3480737 A US3480737 A US 3480737A US 532643 A US532643 A US 532643A US 3480737D A US3480737D A US 3480737DA US 3480737 A US3480737 A US 3480737A
Authority
US
United States
Prior art keywords
signals
tape
line
switch
sampling
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.)
Expired - Lifetime
Application number
US532643A
Other languages
English (en)
Inventor
Sanford David Greenberg
Bert E Norvell
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.)
VSC Co WESTPORT CT A OF LP
Cambridge Research and Development Group
Variable Speech Control Co Vsc
Original Assignee
Cambridge Research and Development Group
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 Cambridge Research and Development Group filed Critical Cambridge Research and Development Group
Application granted granted Critical
Publication of US3480737A publication Critical patent/US3480737A/en
Assigned to VARIABLE SPEECH CONTROL COMPANY reassignment VARIABLE SPEECH CONTROL COMPANY CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: USC COMPANY THE
Assigned to VSC COMPANY THE, WESTPORT, CT A LIMITED PARTNERSHIP OF reassignment VSC COMPANY THE, WESTPORT, CT A LIMITED PARTNERSHIP OF ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: FLAKS, MARVIN, ATTORNEY-IN FACT, VSC COMPANY THE
Assigned to CAMBRIDGE RESEARCH AND DEVELOPMENT GROUP, A LIMITED PARTNERSHIP OF CT reassignment CAMBRIDGE RESEARCH AND DEVELOPMENT GROUP, A LIMITED PARTNERSHIP OF CT SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: VARIABLE SPEECH CONTROL COMPANY THE, A LIMITED PARTNERSHIP OF CT
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00007—Time or data compression or expansion
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor

Definitions

  • This invention relates to information or data processing and more particularly it concerns the representation of wave bearing information on altered time scales.
  • the present invention is particularly suited to the compression of speech. It has been found that the speed with which spoken information can be conveyed is limited more by speaker capabilities than by listener capabilities. Thus, while the average person finds it difficult to say more than 150 words per minute, this and even greater rates of speech can easily be comprehended by the average listener. Further, because of physical limitations of the human speech mechanism, the amount of sound emitted in talking and the time required to formulate this sound is usually far greater than that required to actually convey the information contained in the speech sounds. Thus, if only selected portions of a persons speech could be extracted and run together, then the informational content of his speech could be preserved and maintained in intelligible form while the time required to present the information could be significantly reduced. This, of course, would be of considerable value in a number of fields such as education, news reporting, research etc.
  • the present invention achieves its improved results by causing wave signals to pass along a given path; and then during such passage, the path is scanned successively so that selected waves are extracted and collected.
  • the scanning is carried out by sampling different portions of each selected wave in sequence at different locations along the path.
  • the sampled wave portions are collected and then filtered to remove their sampling. frequency components.
  • Scanning of the various sampling locations distributed along the wave path can be achieved by electronic switching means which as is known to those skilled in the art is capable of operation at rates far in excess of mechanically moving elements.
  • scanning can take place at a faster rate so that the sampled portions of the wave signals are made smaller but more closely spaced. This, of course, reduces the likelihood of important portions of various syllables or other information being lost and yet maintains the same degree of compression.
  • the present invention also involves the use of special electromechanical wave delay lines with special integrated tape arrangements described more fully hereinafter.
  • the present invention comprehends the altering of wave signal information based upon the presence or absence of signals.
  • wave signals are monitored for the presence or absence thereof while they are being transcribed.
  • relative movement between the transcribing element and the transcribing medium is halted, and during the presence of such information, the movement is restored.
  • the transcribed signals are run together on the transcribing medium.
  • This arrangement is particularly effective when used as an integral part of the compression technique described above, for it provides a precompression effect which enhances the sampling compression.
  • a precomprestion transcriber may be used to run words together by eliminating the time periods which separate them. Then upon sampling compression, no sampling is done on signalless waves.
  • the compression technique is rendered more effective.
  • FIG. 1 is a block diagram illustrating one embodiment of the present invention
  • FIG. 2 is a graph useful in understanding the operation of the present invention
  • FIG. 3 is an electrical schematic of a delay line and switching arrangement useful in connection with the present invention
  • FIG. 4 is a section view, taken in elevation showing an alternate delay line
  • FIG. 5 is a mechanical schematic illustrating a synchronizing arrangement useful in connection with the present invention.
  • FIG. 6 is a block diagram illustrating another aspect of the present invention.
  • FIG. 7 is a mechanical representation of a tape drive forming a portion of the arrangement of FIG. 6;
  • FIGS. 8 and 9 are end and side views, respectively, of an alternate tape drive arrangement.
  • the system shown in FIG. 1 includes a variable speed tape playing machine or player 10 through which a signal bearing tape 12 is run.
  • the tape 12 which is supplied from a supply reel 14 and taken up on a take-up reel 16, is impressed, as by magnetization, with various configurations or signals which, when the tape is drawn through the player 10, result in the reproduction of modulated wave signals.
  • the player 10 may be of the conventional sound reproducing variety.
  • the tape 12 may contain sound signals in the usual configuration; and in such event, it is pulled through the player 10 at a rate which may be several times greater than normal. Conversely, signals may be put on the tape 12 while it is run more slowly than normal; and in such event the tape would be played through the player 10 at its normal rate. In either case, the ultimate effect is to produce electrical wave type signals on a player output line 18 which are much higher in frequency than normal. At this point, the wave signals have been compressed by an amount corresponding to the difference in speeds undergone by the tape 12 in recording and in playback. This compression however is unsatisfactory for speech purposes for the compression equally affects all frequency components. Thus, the pitch of the resulting sound is so high as to make the sounds unintelligible.
  • the high frequency wave signals from the player output line 18 are supplied to a delay line 20, which in effect amounts to a wave propagating medium.
  • the delay line 20, which will be described in greater detail hereinafter, serves to retard the waves so that they pass through it at a lower velocity than normal, while still maintaining their increased frequency.
  • a high speed switch 22 is provided alongside the delay line 20.
  • the switch 22 serves to connect a common sampling line 24 successively to each of several tap lines 26 along the delay line 20.
  • the resulting signal produced on the common sampling line 24 is applied to a low pass amplifier 28 and then supplied via a switch 30 to a sound transducer or speaker 32 and/ or to a recorder 34.
  • the switch 22 should operate in synchronism with the speed at which the tape 12 is moved through the player 10; or more precisely, the switching rate should be maintained proportional to the frequency increase produced by movement of the tape through the player.
  • signals are produced in the player 10 and transmitted via a line 31 to the high speed switch 22. These signals cause the switch to operate at a rate corresponding to the rate at which the tape 12 is played.
  • the system of FIG. 1 produces and/or records output sound signals which are in effect composite signals formed by taking only selected portions of the input signals and then bringing these selected portions back together while discarding the remaining portions.
  • the ratio of the discarded to the retained portions of the wave signals may be upwards of 5:1; and yet, the resulting sounds will remain intelligible. It has been found in fact, that with very little practice one can readily comprehend what is being said even though less than 20 percent of the original sounds are actually received by the listener even though the segments constituting this 20 percent is crowded together.
  • the frequency of the signals applied to the system is initially increased, either by passing the tape 12 rapidly through the player 10 or by previously having run it slowly through the recording machine. In either case, the signals and their frequency components become artificially compressed.
  • the player 10 converts the signals to wave type electrical energy which then propagates through the delay line 20 at their increased frequency.
  • the waves are successively scanned from left to right by the high speed switch 22. That is, the switch sequentially makes and breaks contact between the common sampling line 24 and successive tap lines 26.
  • the progressive sampling along the delay line produces an effect similar to the effect produced by a tape player pickup moving from left to right at the speed of progression along the tap lines when a tape being scanned by the pickup head moves from left to right at the speed of progression of waves through the delay line 20.
  • very little time is required to complete a scan and a successive scan may follow very close behind.
  • a greater number of more closely spaced scans may be provided. This permits a more homogeneous sampling of the waves so that for a given amount of compression less information is lost.
  • FIG. 2 illustrates the manner in which output waves are generated on the common sampling line 24.
  • Curve a in FIG. 2 represents the voltage wave of one frequency component Fsig of a wave signal progressing through the delay line 20 at a velocity Vsig.
  • Curve b represents the voltage produced on the common sampling line 24 as a result of the wave of curve a when the switch 22 is in operation.
  • the switch 22 is set to make successive connections from one tap line 26 to the next at a rate progressing down the delay line such that the wave of curve a as observed from each instantly connected tap line appears to progress at a velocity corresponding to its original frequency.
  • the speed or rate of progression at which the scan of tap lines 26 should take place in order to restore the sampled high frequency wave component to its original frequency can be computed in the following manner:
  • the frequency Fsig of a wave signal component which propagates through the delay line 20 at a velocity Vsig can be expressed as:
  • Vsig Vsam Fa ksig The signal component wavelength Asig can be stated as:
  • Vsig Vsa m Vsig represents the factor of compression or number of times greater than Fa that Fsig is.
  • curve a represents voltage or amplitude changes taken at a single location along the delay line 20 at different times.
  • Curve [2 represents voltage or amplitude changes taken at various locations along the delay line 20 at different times.
  • the amplitude of curve a rises rapidly in time at a single location, it does not rise so rapidly when viewed successively at different locations. Actually, if the viewer were to progress along the delay line at the rate of propagation of the wave, it would not appear to change in amplitude at all.
  • the resulting output on the common sampling line 24 is actually a series of spikes or pulse like bursts whose envelope represents the desired signal component. These bursts or pulses contain many undesirable frequency components, however they are all much higher than the desired envelope component. Thus by passing the signals through the low pass amplifier 28 these undesirable high frequency components may be removed so that only the envelope component remains for broadcast in the transducer 32 or for transcription in the recorder 34.
  • FIG. 3 shows a wiring diagram for a delay line 20 and high speed switch arrangement 22 which may be used in connection with the system of FIG. 1. As shown in FIG. 3, there are provided a pair of input terminals 36 and 38 across which electrical wave type signals from the tape player are applied.
  • the terminal 36 is
  • the delay line 20, as shown in FIG. 3, is comprised of a plurality of capacitors 40 which connect in parallel with one another between a ground line 42 and a signal line 44.
  • the ground and signal lines are connected respectively to the termials 36 and 38.
  • a plurality of inductance coils 46 are connected in series along the signal line 44 between adjacent capacitors 40.
  • An energy absorptive termination such as a resistor 48 having a matched impedance characteristic is connected at the right end of the delay line across the ground and signal lines 42 and 44.
  • the resistor 48 serves to dissipate all energy remaining in signals which have passed through the delay line 20 so that they will not become reflected back toward the input terminals 36 and 38.
  • the various tap lines 26 are connected to different junctions 49 along the signal line 42 between adjacent coils 46.
  • the opposite ends of these tap lines are connected to corresponding switch contacts 50 which are arranged in circular formation about a central axis 52.
  • a wiper arm 54 is mounted to rotate continuously about the central axis 52 and to sequentially contact each of the switch contacts as it rotates.
  • the common sampling line 24 is connected to the wiper arm 54 so that as the wiper arm rotates the sampling line 24 is effectively tapped into the delay line 20 at different locations therealong in sequence.
  • the entire delay line 20 is thus scanned from left to right once for each rotation of the wiper arm 54; and upon completion of the scan a new scan is begun immediately, beginning at the left end of the delay line.
  • the scanning speed Vsam depends, of course, upon the rotational speed of the wiper arm 54.
  • the time taken for a wave to pass from one end of the delay line to the other should be long relative to the wave length of the waves applied to the delay line.
  • it should take between 10 and 100 milliseconds for the Wave to pass from one end of the delay line to the other and normally, the length of the line would be such that the time taken is between 20 and 40 milliseconds.
  • the taps on the delay line should be about 50 microseconds apart.
  • FIG. 4 illustrates a different arrangement for the delay line 20 and the high speed switch 22.
  • the signal bearing waves are of the mechanical or vibratory as opposed to electrical or radiative.
  • an electro-mechanical transducer which converts signals which appear on the player output line 18 to mechanical vibrations. These vibrations are launched into the left end of the delay line 20 and they propagate through the line as acoustical waves.
  • the delay line 20 itself comprises an elongated tube 62 of insulated type material.
  • the tube 62 is filled With a liquid 64 into which the vibratory waves are launched. These waves travel from the left to the right end of the tube 62 and then become dissipated in an acoustically absorbent material 66 at the right end of the tube.
  • An electrically conductive strip 68 is aifixed to the tube 62 and extends along its length on one side.
  • a plurality of electrically conductive elements 70' are affixed along the opposite side of the tube.
  • the elements 70 are connected by means of the tap lines 26 to the high speed switch 22.
  • the common sampling line 24 from the high speed switch and a further line 24a from the conductive strip 68 are connected into the tank circuit of an oscillator 72.
  • the oscillator output is connected to a frequency discriminator 74 and the output of the frequency discriminator 74 in turn is connected to the low pass amplifier 28.
  • the delay line arrangement of FIG. 4 operates in the following manner. Signals from the player output line 18 are converted to mechanical vibrations in the transducer 60 as above described and are launched into the tube 62 and propagate therethrough as acoustical waves. While passing through the line 20, the waves produce compressions and rarefactions in the fluid in directions both in and transverse to their direction of propagation. These compressions and rarefactions result in variations in the physical displacements between the elements 70 and the strip 68; and this in turn changes the electrical capacitance between the elements and the strip by corresponding amounts.
  • the oscillator will produce an output frequency corresponding to the value of the capacitance existing between the particular element 70 and the strip 68.
  • the resulting variations in oscillator output frequency are detected in the frequency discriminator 74.
  • the output of the discriminator 70 thus corresponds to the capacitance at the particular element 70 which happens to be connected at that instant to the sampling line 24 by the high speed switch 22.
  • the acoustical waves which proceed through the tube are sampled and converted to corresponding electrical signals which are similar to the signals shown in curve 12 of FIG. 2.
  • These signals are then passed through the low pass amplifier 28 where their high frequency oscillator and sampling components are attenuated relative to the remaining portions of the signals.
  • the signals then proceed to the sound transducer and/or the recorder 34 as above described.
  • the scanning speed Vsam at which the high speed switch 22 makes contact from tap line to tap line should be properly related to the propagation velocity Vsig of the Wave signals passing through the delay line 20 in order for frequency components of the output signals to be restored to their original condition.
  • the freqluency components were increased by a factor n by moving the tape 12 through the player 10 at a rate greater than that it which it was moved when being recorded.
  • the system since the system operates to remove a considerable portion of the original input signals, it is important, in order to preserve intelligibility, that the remaining portion of these signals be as representative of their original condition as possible.
  • FIG. illustrates schematically an arrangement which serves to maintain the scanning velocity Vsam in proper relationship with the signal velocity Vsig even though the speed at which the tape 12 is drawn through the player may vary.
  • the take-up reel 16 is driven by a tape driver motor 80.
  • the speed of the tape drive motor 80 in turn is controlled by means of a motor speed control unit 82.
  • the motor speed control unit 82 may be adjusted by means of a manual speed control knob 84.
  • a toothed wheel 86 is mechanically linked to the take-up reel 16 and to the tape drive motor 80 so that it turns in synchronism with these elements.
  • a magnetic head 83 which is comprised of a magnetic core 90 and a coil 92 would thereabout, is positioned in close proximity to the rotating toothed wheel 86.
  • the teeth of the wheel 86 pass in front of the core 90 they alter the magnetic flux in the vicinity of the coil 92 and produce electrical impulses upon the line 31 connected to the coil. As indicated previously, the line 31 is connected to operate the high speed switch 22. Thus as the tape drive motor 80 causes the take-up wheel 60 to pull the tape 12 at different speeds, the tooth wheel 86 will also operate at different speeds, thus producing a greater rate of impulses upon the line 31 to operate the high speed switch 22 in a corresponding manner.
  • the present invention in one of its aspects provides for precompression of wave signals by eliminating or reducing substantially the time periods during which no signals are being produced or emitted.
  • original speech is broadcast into a microphone 100 which is connected to a tape recorder 102, and the tape recorder in turn reproduces the speech signals upon a magnetic tape 104 which is pulled through the recorder. Thereafter, the tape 104 is replayed on a tape player 106.
  • This tape player as indicated in FIG. 6 operates at n times the original recording speed in order to achieve a frequency compression effect as described previously.
  • the electrical signal outputs from the tape player 106 are supplied via an output line 108 and a delay line 110 through an electronic switch 112 to the record head of a start-stop tape recorder 114.
  • the tape player 106 and the startstop tape recorder 114 are mechanically coupled so that the start-stop tape recorder 114 when operative, will operate at the same speed as the tape player 106, so that no change will be made to the various frequency component of the signals being transcribed.
  • the signals present upon the output line 108 are also supplied to a detector 118, and from there they proceed to a signal responsive switch 120.
  • the signal responsive switch will produce on or off signals on a line 122. These on and off signals control the operation of the electronic switch 112.
  • the signal responsive switch 120 also produces start and stop signals on a line 124 for controlling operation of the start-stop tape recorder 114.
  • the tape 104 is moved at constant speed through the tape player 106.
  • a second tape 126 is moved through the start-stop tape recorder 114.
  • the second tape 126 proceeds at the same speed as the tape 104; however, the tape 126 moves only when actual signals are proceeding into the start-stop tape recorder 114.
  • the signal responsive switch 120 When no signals are present upon the output line 108, the signal responsive switch 120 operates to turn off the electronic switch 112 thus preventing the occurrence of signals into the start-stop tape recorder 114, and at the same time, it produces a stop signal on the line 124 to stop the movement of tape 126 through the recorder 114.
  • the signal responsive switch when signals are present on the output line 108, the signal responsive switch produces a signal on the line 122 to open the electronic switch 112 thus permitting the signals to pass into the start-stop tape recorder 114 and at the same time, it produces a signal on the line 124 to start movement of the tape 126 through the recorder 114.
  • the delay line 110 serves to hold the back signals until the start-stop tape recorder is up to proper speed.
  • the electronic switch 112 serves to insure that signals go into the start-stop tape recorder 114 only when the tape 126 is being moved through the recorder.
  • FIG. 7 illustrates a mechanical arrangement for the tape player 106 and the start-stop tape recorder 114.
  • the tape 104 passes over a pair of drive drums 128 and 130 and moves over a pickup head 132 located between the drums.
  • the drums 128 and 130 are driven at constant speed and the tape 104 is held or crushed against the drums by means of presser elements 131 so that it moves continuously over the pickup head 132.
  • Electrical output signals are produced by the pickup head corresponding to the magnetic configurations on the tape; and these output signals are transmitted along the output line 108 as indicated above.
  • the tape 126 passes along over the opposite side of the drums 128 and 130 and over a record head 134, also located between the drums.
  • a pair of movable pressure shoes 136 and 138 are mounted on a common yoke 140 and operate, when the yoke 140 is pressed downwardly to crush the tape 126 into the drums 128 and 130 so that it is driven by them across the record head 134. When the yoke 140 is lifted, the tape 126 will remain stationary as the drums 128 and 130 slip over it.
  • the up and down movements of the yoke 140 are controlled by means of a solenoid 142 which receives signals via the start-stop line 124 connected to the signal responsive switch 120.
  • the fully transcribed tape 126 which has moved only when signals were present, contains only signal bearing portions. There is thus effected a precompression of the signals originally on the tape 104.
  • FIGS. 8 and 9 illustrate an alternate form of tape player and start-stop recorder.
  • a single drum 150 which rotates continuously about an axis 152.
  • the tape 104 as shown in FIG. 9 passes around the drum 150 and moves continuously with the drum while the pickup head 132 monitors the signals on the moving tape.
  • the tape 126 passes around the drum 150 but extends a considerable distance out beyond the drum so that it contacts the drum only over two relatively small sectors 154 and 156.
  • the portion of the tape 126 which extends out beyond the drum 150 loops over the record head 134.
  • Start and stop signals from the signal responsive switch 120 are supplied via the line 124 to a solenoid 158.
  • the solenoid 158 in turn operates through a linkage mechanism 160 to cause a pair of pressure shoes 162 and 164 to crush the tape 126 against the drum to be driven thereby.
  • the signal responsive switch 120 produces a stop signal which de-energizes the solenoid 158 so that it releases the linkage mechanism 160, allows the shoes 162 and 164 to release the tape 126 so that it will not move, although the drum 150 continues to rotate.
  • the tape 104 moves continuously along with the drum 150, the tape 126 will move only when signals are available to be recorded on it.
  • apparatus for modifying modulated wave signals means for changing the frequency components of said wave signals by a given factor, means for directing movement of said signals along a given path, a plurality of sampling means distributed along said path for sampling different portions of selected ones of said wave signals as they pass by, switch means arranged to activate each of said sampling means sequentially in successive scans along said path, means arranged to control the operation of said switch means in relationship to the operation of said means for changing the frequency components of said wave signals, and output means for receiving signals from each sampling upon activation thereof, said output means including filter means operative to attenuate the sampling frequency components relative to the sampled signal portions.
  • said means for changing the frequency component of said wave signals includes a variable speed tape playing device having means synchronized to the tape drive of said device for producing switch means control signals corresponding to the speed of movement of tape through said device.
  • said means for producing switch means control signals comprises a toothed wheel mounted to turn with the tape drive said device and an iron cored coil positioned in proximity to said wheel.
  • Apparatus for reproducing signals recorded on a recording medium and corresponding to audio frequency signals generated during a predetermined time and for providing output signals corresponding to said audio frequency signals and in the audio frequency range but within a time less than said predetermined time, said apparatus comprising means for generating signals from said medium which are modified signals having frequency components which are increased by a given factor relative to the frequency components of said audio frequency signals, a delay line, means for supplying said modified signals to said delay line, said delay line having a plurality of sampling means distributed therealong for sampling different portions of selected ones of said modified signals as they travel along said line at predetermined velocities, output means, switch means for sequentially connecting said sampling means to said.
  • control means for operating said switch means in a predetermined relation to said generating means and so as to scan said sampling means successively at a rate which is less than the velocity of the modified signals in said delay line but at a frequency higher than the frequencies of said modified signals thereby to provide further modified signals having frequency components in the audio frequency range and lower than the frequency components of said modified signals and having sampling frequency components, said output means also comprising filter means operative to attenuate said sampling frequency components relative to the other components of said further modified signals.

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Signal Processing Not Specific To The Method Of Recording And Reproducing (AREA)
  • Recording Or Reproducing By Magnetic Means (AREA)
US532643A 1966-03-08 1966-03-08 Apparatus for reducing time duration of signal reproduction Expired - Lifetime US3480737A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US53264366A 1966-03-08 1966-03-08

Publications (1)

Publication Number Publication Date
US3480737A true US3480737A (en) 1969-11-25

Family

ID=24122597

Family Applications (1)

Application Number Title Priority Date Filing Date
US532643A Expired - Lifetime US3480737A (en) 1966-03-08 1966-03-08 Apparatus for reducing time duration of signal reproduction

Country Status (4)

Country Link
US (1) US3480737A (enrdf_load_stackoverflow)
JP (1) JPS5019882B1 (enrdf_load_stackoverflow)
DE (1) DE1547017A1 (enrdf_load_stackoverflow)
GB (2) GB1173682A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3621150A (en) * 1969-09-17 1971-11-16 Sanders Associates Inc Speech processor for changing voice pitch
JPS4835703A (enrdf_load_stackoverflow) * 1971-08-13 1973-05-26
US3828361A (en) * 1971-08-13 1974-08-06 Cambridge Res & Dev Group Speech compressor-expander
US3838218A (en) * 1972-03-07 1974-09-24 Cambridge Res & Dev Group Bifrequency controlled analog shift register speech processor
US3846827A (en) * 1973-02-12 1974-11-05 Cambridge Res & Dev Group Speech compressor-expander with signal sample zero reset
US4771345A (en) * 1985-09-12 1988-09-13 Sharp Kabushiki Kaisha Reproducing apparatus

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU459101B2 (en) * 1972-02-10 1975-03-20 Matsushita Electric Industrial Co., Ltd. Samplling modulation system for an electronic misical instrument

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1735037A (en) * 1926-08-12 1929-11-12 American Telephone & Telegraph Method of and apparatus for reducing width of transmission bands
US2640925A (en) * 1952-04-09 1953-06-02 Hazeltine Research Inc Electron discharge signal-sampling device
US2650949A (en) * 1948-07-09 1953-09-01 Veaux Henri Maurice System of changing the frequency band occupied by a telephonic transmission

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1735037A (en) * 1926-08-12 1929-11-12 American Telephone & Telegraph Method of and apparatus for reducing width of transmission bands
US2650949A (en) * 1948-07-09 1953-09-01 Veaux Henri Maurice System of changing the frequency band occupied by a telephonic transmission
US2640925A (en) * 1952-04-09 1953-06-02 Hazeltine Research Inc Electron discharge signal-sampling device

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3621150A (en) * 1969-09-17 1971-11-16 Sanders Associates Inc Speech processor for changing voice pitch
JPS4835703A (enrdf_load_stackoverflow) * 1971-08-13 1973-05-26
US3828361A (en) * 1971-08-13 1974-08-06 Cambridge Res & Dev Group Speech compressor-expander
US3838218A (en) * 1972-03-07 1974-09-24 Cambridge Res & Dev Group Bifrequency controlled analog shift register speech processor
US3846827A (en) * 1973-02-12 1974-11-05 Cambridge Res & Dev Group Speech compressor-expander with signal sample zero reset
US4771345A (en) * 1985-09-12 1988-09-13 Sharp Kabushiki Kaisha Reproducing apparatus

Also Published As

Publication number Publication date
JPS5019882B1 (enrdf_load_stackoverflow) 1975-07-10
DE1547017A1 (de) 1970-01-15
GB1173682A (en) 1969-12-10
GB1173683A (en) 1969-12-10

Similar Documents

Publication Publication Date Title
KR100621424B1 (ko) 다이나믹 오디오 프레임 배열에 의해 비디오/오디오데이터 동기된 프레임 기반 오디오 코딩
KR930002147B1 (ko) 음상 묘사 방법 및 장치
US5105462A (en) Sound imaging method and apparatus
US5208860A (en) Sound imaging method and apparatus
US3786195A (en) Variable delay line signal processor for sound reproduction
US3480737A (en) Apparatus for reducing time duration of signal reproduction
US2327956A (en) Magnetic recording and reproducing
US2886650A (en) Recording device
US3594513A (en) Apparatus for eliminating silent intervals between signals
US3973839A (en) Special effects generation and control system for motion pictures
US3974329A (en) Transmission of video pictures at audio frequencies
US2286072A (en) Treatment of speech waves for transmission or recording
US2512015A (en) Device for producing sound effects
US2681387A (en) Magnetic record reproducing system
US3584158A (en) Helium speech unscrambler
US3053941A (en) Magnetostrictive transducer for the recording and reproducing of magnetic information
US3095482A (en) Method of and apparatus for signal reproduction
JPH0244502A (ja) 磁気記録・再生装置
US2658950A (en) Reproducer for magnetically recorded signals
US3828361A (en) Speech compressor-expander
US2401889A (en) Secret telephony
US2876294A (en) Magnetic record control method and circuits
US2126370A (en) Sound recording and sound reproducing and locating apparatus
US2748192A (en) Reverberation generator
USRE30278E (en) Special effects generation and control system for motion pictures

Legal Events

Date Code Title Description
AS Assignment

Owner name: VSC COMPANY THE, WESTPORT, CT A LIMITED PARTNERSHI

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:FLAKS, MARVIN, ATTORNEY-IN FACT;VSC COMPANY THE;REEL/FRAME:004022/0598

Effective date: 19761215

Owner name: VARIABLE SPEECH CONTROL COMPANY

Free format text: CHANGE OF NAME;ASSIGNOR:USC COMPANY THE;REEL/FRAME:004022/0602

Effective date: 19811214

AS Assignment

Owner name: CAMBRIDGE RESEARCH AND DEVELOPMENT GROUP, 21 BRIDG

Free format text: SECURITY INTEREST;ASSIGNOR:VARIABLE SPEECH CONTROL COMPANY THE, A LIMITED PARTNERSHIP OF CT;REEL/FRAME:004040/0166

Effective date: 19820809