DE2404282A1 - SPEECH PRESSER - Google Patents

Description

Patent attorney

Kar! A. B ro se

Dip '.-'. R.g-

D-8G23 Munich - Pullach
W «B6ß! R.2j.Hdin.7« 0570.793l782

vln / au Munich-Pullach, January 29, 1974

CAMBRIDGE RESEARCH AND DEVELOPMENT GROUP, 21 Bridge Square, Westport , Connecticut 06880, USA - SAIiFORD DAVID GREENBERG, 600 New Hampshire Avenue, NW Suite 600, Washington , DC 20037, USA - DT LIQUIDATING PARTNERSHIP c / o Jay M. Haft, Esq. , 55 Broad Street, New York , New York 10004, USA - MURRAY MORTON SCHIFFMAN, 10 Sunny Lane, Westport. Connecticut Ό6880, USA

Speech presser

The invention relates generally to sound or speech pressers which a recorded sound reproduces at a speed different from the speed at which the sound was recorded and the frequency components of the recorded signal can be restored to approximate those of normal speech which was recorded, so that a recording with normal voice frequencies can be played back, but with a elapsed time different from that while the record was made. if the playback transport is performed at a higher speed than the recording speed, the Time pressed and the information is played back in a shorter time than the time it took to record was required. If the transport is carried out at a slower speed, then the recording g> speed or time stretched and the information is

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is played back for a longer period of time than that for recording was required. With the subject of the present application Pressing is used as a generic term, which means that both a time press and a Time expansion is possible and thus the compression ratio C is greater is as a relationship for the time pressure and a ~ 'ert between zero and less than one for time expansion.

According to the invention, an improved language presser stretcher is used Sawtooth generator for controlling a voltage controlled period generator for application to a square wave with linearly variable periodicity, so daii. through this the shift period of analog shift registers controlled who can, through which the time-pressed sound signals for the frequency recovery can be performed. The I ίο gate speed control unit and the sawtooth generator are controlled by a single manual control device to set the press ratio to select, so that thereby the speed at which the transport motor runs with the selection of the slope of the sawtooth is coordinated, and ultimately the change & lge controlled by the linear period change of the square wave generator which results in the desired frequency transformation for the recovery of the normal frequency spectrum of the sound or speech signals is achieved. When the signals pass through through the analog shift registers, the delay registers are separated into two equal sections and the signal is grounded shifted through the two halves of the analog shift register, signal inversion being performed for signals that get through half of the square. The signals wavered tapped from the outputs of the two halves of the register and combined with one another, either one after the other or in parallel and in each case the processing interference component, that by supplying the linearly variable

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Square wave introduced as a shift period for the registers is eliminated by the inversion technique while the sound signal components are treated additively, thereby improving the signal value and the value of the processing noise component is greatly reduced. At the end of the periodic fluctuation or change in the analog shift register, a improved zero crossing demodulation is performed on the signal and it further increases the audio output during reset the sawtooth voltage and the control period generators during the deletion or deletion of the signal stored there and the period for reloading the register before the output signal reappears at the output terminals. In addition, the present invention provides improved control of the repetitive sample period, the relation of the sample obtained and the deletion time with the properties of the human language and the selected one To make the compression ratio optimal. Signal storage is also used to fill in the time interval during the reset (i.e. gap filling) used according to the invention, this storage being particularly useful during stretching, at which the gap in the output signal at low stretch ratio sen can be undesirable for other reasons.

Further advantages and details of the invention emerge from the description of an exemplary embodiment below Reference to the drawing. It shows:

FIG. 1 is a block diagram with details of an entire speech press system according to the present invention;

Figure 2 is an overall block diagram, partially schematically a signal presser and control circuits of the

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same are illustrated;

Figure 2A is a schematic circuit diagram of the voltage controlled Period generator;

Fig. 2B is a waveform diagram useful for explanation the operation of the device of Figure 2A is useful;

Figure 3 is a waveform diagram of the "" control device for the blanking switch-on and blanking gate control of the output variable;

FIG. 4a is a schematic circuit diagram of the automatic blanking turn-on and reset circuit;

FIG. 4b shows a diagram to illustrate the mode of operation of the sawtooth generator with changing Pressing period;

FIG. 4C shows a diagram to illustrate the mode of operation of the sawtooth generator at an almost constant rate Period for stretching;

FIG. 5 shows a block diagram of an additional circuit in order to thereby achieve a gap filling;

FIG. 6 shows a modified embodiment of the device according to FIG. 4A, in order to thereby automatically change the repetition period for the stretching achieve;

Figure 6a shows the operating characteristics of the circuit of fi

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gur 6; and

Figure SB shows a diagram to illustrate the operation of the sawtooth generator, the modified Embodiment according to Figure 6 is applied to a variable repetition " period for the time expansion to reach.

In Figure 1 is a complete tape replay unit with facilities and features for voice pressing according to the present invention are shown. The unity includes the ordinary Recording storage and transport system to move a sound recording relative to or past a transducer, to thereby obtain an electrical signal which reproduces the recorded sound. In Figure 1 is a pair of Reels 11 and 12 can be seen, and these contain a magnetic recording tape 13 which moves past a playback head 14 is when the coils 11 and 12 with or without a Capstan drive for the tape can be rotated as is well known in the art. The transducer in the playback head 14 generates an electrical signal on line 15 which corresponds to the sound recorded on tape 13, or reproduces. The frequency spectrum of the electrical signal on line 15 is determined by the speed, with which the tape 13 is attached to the transducer in the playback head 14 is moved past and for this purpose the drive of the reels 11, 12 and / or the capstan drive for the tape 13 controlled by a variable speed motor 16. The speed is controlled by a manual control device 17 is selected and this controller can be set to a range of speeds, with speeds are present that are equal to, greater than and less than the speed at which the sound recording was originally

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initially on tape 13.

The signal on line 15 passes through a preamplifier-equalizer 21, which can be equipped with an automatic volume control and further in a suitable Veise forms the signal and compensates for the frequency response that occurs during magnetic recording, and this device with a transducer system can be equipped and generates an analog audio signal with a relatively constant amplitude on the line 22, which represents the sound or speech signal. The signal on line 22 passes through a frequency converter processor 25, which is under the control of a control circuit 24, in order to convert the frequency spectrum of the signals on line 22 into normal speech domain frequency signals on line 25. The peculiarities of the circuits 2'j and 24 are described in more detail below.

The frequency-recovered signal on line 25 ^: is amplified for audio reproduction in an amplifier 26, which can have the usual volume control 27 and sound control device 28, and is also fed to a blanking control device 29 in order to output an output signal on line 31 which is converted into an audible reproduction signal by the audio converter 32. In order to coordinate the mode of operation of the device so that the frequency transformation corresponds to that required for the speed selected for the motor 16, the manual control device 17 is also coupled at 33 in order to control the mode of operation of the control circuit 24 and the frequency processor 23, thereby enabling the desired frequency recovery of the signals processed by the unit 23.

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In the following, with reference to FIG. 2, the general Arrangement of the frequency processor 23 and the control circuit 24 will be described.

The hand control device 17 can select the number of engine revolutions with the aid of the control circuit 44. The motor control circuit 44 also provides, depending on the setting of C, an output signal which is fed to an f (c) circuit 45, which transforms the linear setting of C at the control device 17 into a voltage on the line 41 which, for example, is the Function K C - 1 obeys as

C + 1
the functional relationship for building up the slope of the sawtooth or the sawtooth voltage as a function of the compression factor C.

As stated in the other patent applications of the same applicant, the delay, which is a linear function of time with a sequence d during the entire sampling period, produces the desired frequency transformation, where d = 2 C − 1 .

C + 1

For an incremental delay, as is the case with analog shift registers is obtained, which are controlled by shift pulses with geometrically increasing period, provides this Relationship for the f (c) function with regard to the instantaneous incremental delay d an exact frequency transformation, especially for medium or medium values of C. Wherever high compression values are required (for example C- <0.5 or C> 2.0) is a more accurate Furi & ion for d, which also takes increasing quantization deviations into account, as follows:

d = In C = 2

C-1 +

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This f (c) input on line 41 from the sawtooth generator 42 generates a sawtooth voltage on the output line 46, which has a predetermined steepness and repetition interval, which is determined by the input voltage on line 41. The sawtooth generator 42 is raised by the signal on line 53 and the slope of the sawtooth voltage is determined by the input signal on line 41. The basic period of the sawtooth voltage decreases with increasing slope for compression ratios of C that are greater than one and this property can also be used for fourth of C, which are less than one, as will be explained in more detail below.

The voltage V _EC on line 41 is fed on line 47 to an Au stasb-Frei circuit 43 which determines whether the unit is in the compression mode or operation, this being done by sampling the voltage on the line

47 relative to a fixed value such as 7.8 volts will. If the voltage on line 47 is above 7.8 volts, the unit compresses the speech for a C greater than one and for this state, the blanking enable circuit 43 generates two output variables when the sawtooth voltage swings reach their final values of 2 volts. By sampling an input on line 48, that is from the output of the sawtooth generator 42 on line 56, the blanking enable circuit 43 on line 49 generates a Blanking enable signal when the input variable is on the line

48 crosses the three-volt value and generates on line 51 a reset signal when the signal on line 48 reaches the ¥ ert of 2 volts, which is the designated end of the Is sawtooth period. When the end of the sawtooth period is reached, the sawtooth voltage is 2 volts is reached, the reset pulse on line 51 triggers

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a univibrator 52, which is connected to the line 53 to reset the sawtooth generator 42 and at the end of the Reset pulse of the univibrator, which resets the sawtooth generator 42 to 7.8 volts, the next sawtooth deflection begins. The length or duration of the reset pulse of the univibrator from unit 52 is long enough so that the sawtooth generator can be reset to 7.8 volts as a starting point.

The output variable V _{c of} the sawtooth generator 42 is fed to a voltage-controlled period generator 54, which is based on the

Line 55 generates a square-wave output variable which has a pulse period which varies linearly with the linear change in the sawtooth voltage Vp. An embodiment of the voltage-controlled period generator 54 is shown in Figure 2A, and this consists of a current generator 56, which generates the current UL, and a current generator 57, which selectively generates a current 21> j in the opposite direction, both currents in addition can be used to charge and discharge a capacity 58. The current I ^ of the generator 56 flows continuously and the current 2I-j through the generator 57 flows selectively in the opposite direction in order to build up the voltage across the capacitance 58. The control of the generator 57 takes place in accordance with the function Vp, which has the form of an activated and deactivated signal and originates from the output 60 of a flip-flop 59. The state <fes flip-flops 59 is caused by the output variables of two voltage comparison stages 61 and 62, which each _{receive the voltage V p} from the capacitance 58 as input variables. The comparison stage 61 receives as a further input variable "a voltage E, which has a fixed, previously determined value. The other input <& r comparison stage 62 is supplied with the input voltage V _c from the sawtooth generator 42. The fixed voltage E is always

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greater than the input voltage V ^ ,.

The mode of operation of the circuit according to FIG. 2A can be expanded with reference to the diagram of FIG. 2B, the constant voltage E being indicated in the latter diagram and the discharge current I ₁ causing the voltage across the capacitance

58 falls at a constant rate, as indicated at 63, until the voltage _{value V c is} reached, whereupon the output variable Vp switches on the current from the generator 57 and the current two 2I ₁ charges the capacitance 58 according to the straight charging path 64. The slopes 63 and 64 are the same and opposite, since the discharge speed I _{1 is} canceled and has been made equal in exactly the opposite direction by the charging current 2I _1. As soon as the deflection 64 reaches the voltage value E, the flip-flop changes

59 its state, Vp is removed as a control voltage, thereby _{interrupting the generation of 2I 1} in the current generator 57. The process repeats, as indicated in Figure 2B, and with a linearly changing input voltage V _c , the period of the control waveform Vp is shown as a succession of square waves, the period of which increases linearly with time. This output variable Y " arrives at the line 55 as the output variable of the voltage-controlled period generator 54. Typically, the shift period for the 256 shift stages of the memory delay, as corresponds to the exemplary embodiment selected here, can vary between four microseconds and 62.5 microseconds.

The ■. ■ For an elongation, ^r elle form according to Figure 2B modified in that the slope of V _c ι a positive result and the beginning at the minimum ¥ ert of V is carried out. This \ conditions in the circuit of Figure 2A lead to the decision

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stand an output pulse waveform Vp with pulses a initial maximum width and with a pulse period that is linear with time between the endpoints at earlier Position has been explained, is decreasing.

The output on line 55 becomes a phase split driver circuit 65, which generates square waves in antiphase at the outputs 66 and 67, the square wave input variable on line 55, which correspond to the φ ^, ψ "-driver sizes are to pass the analog signals through a Shift pair of analog shift registers 68 and 69 with 256 storage stages.

The shift registers 68 and 69 are connected to remove signal processing interference caused by operation of the units are introduced at a changing shift pulse period. For this purpose the audio signal appears on line 22 from preamplifier 21 in Figure 1 at the input terminal 71 of an amplifier 72 whose output with the. Input of the analog shift register 68 is connected and is also connected to an inverter 73. The output of the inverter 73 is input to the analog Shift register 69. The output variables of the shift registers 68 and 69 reach a difference verse as subtractive input variables amplifier unit at the input of an audio amplifier unit 74.

The circuit described above, which contains the shift registers 68 and 69, the amplifier 71 and the inverter stage 72 together with the differential amplifier Tk , provides a frequency transformation of the input signal on the line 71 and at the same time ensures that the disturbances and Distortion effects caused by processing

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of the signal were introduced through the shift registers 68 and 69.

In the amplifier 74, the difference signal is further amplified, which is obtained by connecting the two input variables from the shift registers 68, 69 is amplified and the amplified audio signal appears on line 25. In the unit 74 also includes a zero crossing detector which generates a series of pulses on line 75 representing the zero crossing times of the difference signal.

A blanking non-blanking control circuit 76 receives the Zero crossing pulses on line 75 and operates when ready by the blanking enable signal on line 49 or was released and then generates a blanking signal on the line 77, through which the output of the Audio amplifier 74 is blanked. This arrangement allows the value of the output signal to be on the line 25 during the reset period for the shift registers and the controlled sections of the sawtooth generator of the circuit can be gated to a signal level of zero. Circuit 76 is responsive to a signal on line 78 to terminate the blanking signal on line 77, whereby the signal on line 25 is given the opportunity to wisfer return its signal value.

A counter 81 generates on line 78 at the end of the 256 counting steps an output variable, these counting steps corresponding to the length of the individual registers 68, 69, the counter is responsive to the pulses on line 55 applied to counter input 82. When the counter 81 is a count of 256 input pulses on line 82, it generates an output on line 78 through which the

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Blanking period pulse on line 77 is terminated. A output pulse similar to the pulse appearing on line 53 appears on line 83 and resets counter 81. The interval controlled by counter 81 at Counting 256 pulse signals on the line 55 leads to a blanking period for the amplifier 74, which is sufficient so that the pulses on line 55, after having passed through driver stages 65, shift registers 68,69 and read out the contents thereof before the blanking ceases and the audio output on line 25 is restored will. At the same time, the shift pulses are applied to registers 68, 69 to remove the audio signal from the terminal 71 via the amplifier and the inverter stage 72, 73 so enter that the registers 68, 69 are filled at the end of the blanking interval and are ready to input audio samples of amplifier 74 and the next signal period occur can.

If there is no zero crossing signal on line 75 occurs during the standby period indicated by the signal is determined on line 49 before the occurrence of the reset signal on line 51, the reset signal causes which is fed to the counter 81 on the line 83, immediately there? A blanking signal arises on the line 78, which arrives at the circuit 76 in order to blank the audio amplifier 74 by means of a suitable signal on the line 77. By the action of the counter 81, the signal on line 78 is removed in order to ameliorate the blanking signal on line 77 End of counting of 256 pulses on line 82 to remove. The audio output size is therefore for the duration of the Output pulse of the reset univibrator 52, plus the period required to count 256 counts in counter 81 is, plus the time interval after the end of the 256-

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first counting step for the detection of the next signal zero crossing blanked.

The blanking-not-blanking control logic 76 includes a D flip-flop and for inputs on lines 49, 75 and 78, the output variable is controlled in the manner shown in FIG 3 is illustrated. The release input 49 enables blanking after the occurrence of a zero crossing within the release interval and if this does not take place, the pulse of the reset univibrator on 83 forces the start of the blanking interval by means of a signal on line 78, which is continued in the counter 81 during the 256 counting steps. At the end of the 256 counting steps, the signal enables on line 78 the removal of the blanking signal upon occurrence of the next zero crossing detection signal on line 75, this serves to switch the output variable on line 77.

To reset the univibrator 52 before the saw voltage end signal on line 51 and in synchronization with the detection a zero crossing through the blanking control unit 76, the signal on the line 77 is the pulse generator 101 fed to the univibrator 52 after the occurrence of an output signal to reset on line 77. The output when resetting the univibrator 52 on line 53 thus sets the sawtooth generator 42 to a coincidence with the detection of the first zero crossing after the blanking release and the appearance of such a signal on line 77. This way, the gap in the audio output signal becomes usually reduced by a substantial amount in all cases except when there is no zero crossing during the full duration of the blanking enable signal was detected.

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For the time expansion, i.e. in the event that C is less than one, the voltage signal on line 47, v / elches the Blanking release unit 73 is fed to the tension ring E on line 50, which is 7.8 volts, compared to one Sawtooth voltage with opposite slope and with an essentially constant repetition interval of the sawtooth generator 42 to generate. Also ground an off release signal on line 49 when the ramp voltage reaches its final value of 7.8 volts and the final reset pulse on the Line 51, as described, is generated.

With reference to Figure 4A, the structure of the sawtooth generator 42, the blanking release unit 43 and the reset univibrator 52 and their relationship to one another will now be described in detail. In Figure 4A, the portion on the left-hand side of the dashed line relates generally to the sawtooth generator 42 shown in Figure 2, and the portion on the right-hand side of the dashed line in Figure 4A relates generally to units 43 and 52 in Figure 2. The saw tooth generator 42 essentially contains a voltage capacitance 91 which is supplied by a constant current source 92 and a variable current source 93. The current from source 92 charges capacitance 91 and the current from source 93 discharges capacitance 91. Current generator 93 is _{voltage controlled by voltage V EC} on line 47 such that when signal V ™ is equal to fourth E, the current discharge rate through the source 93 is the same as the current discharge rate from the source 92, so that no voltage change occurs at the capacitor 91. For other values of the voltage V ™, the current drawn by the source 93 is either greater or smaller than the current supplied by the source 92, so that a voltage change then occurs across the capacitance 91. The voltage across capacitance 91

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therefore consists of a positively or negatively increasing ramp voltage or sawtooth voltage, where the sign of the slope is determined by the relative sizes of V ™ and E. and where the value of the slope or incline is determined by the size difference. This ramp-shaped tension appears as an output on line 46 to the voltage controlled period generator 54, as in earlier Place was described to supply the input variable.

For a time pressure, the value of C is greater than one and the voltage V ™ is greater than the voltage E and it has a value determined by the selected value of the compression ratio C and further analogously by the tension this setting, which is generated by the motor control circuit 44, modified by the function circuit 45, is determined will.

In order to control the generation of the ramp-shaped voltage, a number of voltage comparison stages 94, 95, 96, 97 and 98 are provided. The property of the comparison stages 94-98 is to provide a "ONE" output when the plus input is greater than the minus input and to provide a "ZERO ^ output for the opposite condition. The comparison stages 94, 95 and 96, the ramp-shaped voltage or sawtooth voltage of the capacitance 91 is fed to the negative input connections and this same voltage is fed to the positive input connection of the comparison stage 98. The voltage E on the line 50 is fed to the positive input of the comparison stage 97 and the negative input of the Comparison stage 98. The voltage V ^ _n is fed to the negative input of the comparison stage 97 and, furthermore, a voltage between V _EC and the voltage E is fed to the positive input of the comparison stage 96, namely

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with the help of the voltage divider that connects lines 47 and 50 connects to the positive input of the comparison stage 96, which is connected to the connection point of this voltage divider is. The comparison stage 94 receives an input variable of plus 2 volts at its positive terminal and the comparator 95 receives an input at its positive terminal of + 3 volts. The outputs of the comparison stages 94 are interconnected to a logical "NAITO" circuit, to generate the blanking enable signal on line 49 and the reset pulse on line 51 in the following manner:

The blanking enable signal on line 49 is from the NAND gate 105 derived, which receives the input variables from the comparison stage 96 and a NAND gate 106. The NAND -Gate 106 receives inputs from the comparison stage 95 and from an inverter stage 107, the output variable at its input the comparison stage 97 receives.

The reset pulse on line 51 is derived from the output of a NAND gate 108, the input variables to this Gates derived from the outputs of NMD gates 109 and 110 will. The input variables to the NAND gate 109 are taken from the output of the inverter stage 107 and the output of the comparison stage 94 derived. The input variables to the NAND gate 110 come from the outputs of the comparison stages 97 and 98

The reset pulse on line 51 triggers the reset univibrator 52 in such a way that it generates a reset pulse on line 53 which puts a gate 111 in the conductive state controls so that a signal from a buffer verse tare 112 can pass through this gate when this gate is on standby. At the output of gate 111

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The output variable from the amplifier 112 then appears, so that the reset voltage value for the capacitance 91 is thereby built up during the reset. The voltage to which the capacitance 91 is reset is determined by the relative size of Yt? _c and E determined. ^T ; Jenn V ™ is greater than Ξ, then the voltage supplied to the input of amplifier 112 is derived from line 50 with potential E via resistor 113, and as a result, for compression ratios greater than one, the voltage is reset to a constant voltage E If V _E "is less than E, a diode 114 is biased into the conductive state and the input variable of the amplifier 112 corresponds to the potential V _PC and the capacitance 9'1 is charged to the variable voltage value which is determined by V _{T? r is established} on line 47.

In the following reference to the source forms of FIG. 4b, the mode of operation of the circuit of FIG. 4A for a time pressure is explained when C is greater than one. The voltage V ^ _n is greater than the voltage E, so that as a result the comparison stage 97 generates an output variable of Hull and the NAND gate 110 blocks or is set out of readiness. The output variable of the comparison stage 98 thus does not influence the generation of the reset signal on the line 51. The output variable of the inverter stage 107 consists of a one, as a result of which the NAND gate 109 is set to standby and the comparison stage 94 is given the opportunity to control the generation of the reset pulse on the line 51 when the voltage on the capacitance 91 falls below the tert of + volts at the input of the comparison stage 54. The output variable of the inverter pin 107 has also set the NAND gate 106 ready at this point in time, and the output variable of the comparison stage 95 thereby controls the IiAiID gate 105 in order to generate the blanking enable pulse on the line 49,

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when the voltage across the capacitance 91 falls below the value of + 3 volts. The output variable of the NAND gate 96 consists of a one, de the voltage E is greater than the voltage across the capacitance 91 for all values of Vg _C greater than E. This determines the charging sequence or speed of the capacitance 91 through the voltage V ™ changes, but the reset and blanking enable signals v / ground are generated at a constant voltage value of 2 and 3 volts, as shown in Figure 4B, with the resulting change in the repetition period of the sawtooth voltage, i.e. from 7.8 volts falls to 3 and 2 volts with the different slopes, 'is determined by V ™'. For very small compression ratios, greater than one, the period is very long and it is gradually reduced to approx. 30 ms for C = 2 and to 20 ms for C = 3 as typical values. Since V _EC builds up the slope of the ramp voltage, which is nearly proportional to the term C-1 , is

~ C + T the period for C> 1 almost proportional to the expression C + 1 .

A typical value for the period is 10 C + 1 (ms).

C-1

For C = 1, V _{EC is} equal to E and the charging and discharging currents of the capacitance 91 are the same. The voltage across the capacitance remains constant, which effectively results in a slope of the ramp-shaped voltage from zero or a fixed delay is achieved and no frequency conversion takes place by the analog shift register.

In the event that the compression ratio C is less than one, V _{EC is} also less than E and the output of the comparison stage 97 is a one, whereby the NAND gate 110 is set in readiness so that the output of the comparison stage 98 to generate the Reset signal on the line 51 can control. The output of the inverter stage

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is a zero, thereby disabling HAND gates 106 and 109. In the event that the voltage at the capacitance 91 becomes greater than ER (EV _EC ), the Ron constant R being able to be almost 0.1, as determined by the voltage divider to which the positive input of the comparison stage 96 is connected, the output variable of the comparison stage 96 becomes a Hull and a blanking enable signal is generated on the line from the NAND gate 105. When the voltage of the capacitance 91 reaches the end of the ramp-shaped voltage at E, the output variable of the comparison stage 98 consists of a one, thereby generating a reset pulse on the line 51 via the NAND gates 110 and 108. This mode of operation is shown in Figure 4C, with various values of Vr, «being shown as the starting point for the ramp-shaped voltage which rises to the voltage E of 7.8 volts. The variable ER (EV _EC ) changes somewhat with the value of Vp ~, whereby the blanking enable point on the ramp-shaped voltage changes (this is shown enlarged in FIG. 4C), but the period of the ramp-shaped voltage is kept almost constant. A typical repetition period of the system which is illustrated is 40-50 ms.

In certain language press application cases, especially in the In case of stretching, it is useful to reduce the disturbance, which is caused by the gaps that result from the blanking between samples, which is caused by filling the splitting can be done with an adequate signal. In the following, FIG. 5 will now be discussed, which shows the general arrangement of the additional functional components that are required to make up the mentioned column fill with slightly delayed portions of the processed signal. The signal from the audio output on line 25 of Figure 2 is fed to a prestressing network 172 and gc-

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there reaches into an analog delay line 168. A square wave 155 with constant frequency, which comes from the generator, generates complementary drive signals with constant Frequency on lines 165 and 166, thereby causing the signal on delay line 168 to decrease by a fixed Amount at the output on line 151 is delayed. The output 78 of the counter 81 of FIG. 2 sets a flip-flop 176 at D in readiness, so that this emits a gate control signal on the line 177, in which every change of state through a zero crossing pulse 175 of the detector 174- triggered will. Said gate control signal 177 serves to divide the delayed audio signal 151 between a beginning and an ending Zero crossing during the blanking interval of the applied processed signal 25 not to be blanked. The resulting gated-delayed signal, which is normalized in a suitable manner in the amplifier 174, is then with the basic processed signal 25 in the summing amplifier 148 to form a composite audio signal on the Line 150 to generate.

Figure 6 illustrates a modified embodiment of the article of Figure 4A that is more suitable for gap fill stretching (gap filling expansion) is. Clamp amplifier circuits 115, 116, 117 have been added to the property of the To change the sawtooth reset during the stretching operation (C <1) so that a change in the period as a function of the To enable pressing ratio C as for pressing operation (C> 1), however, a smoother or smoother transition should still be maintained when thinking of stretching (C <1) switched to compression (C ^> 1) and vice versa. To this Purpose, the voltage E on the line 50 is fed as an input variable to the amplifier 116, which has a gain of

A-1 has and this output with the negative input of a Dif-A

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reference amplifier 115 is connected. The positive input of the amplifier 115 consists of the voltage V- _c derived from the line 47. The output of amplifier 115 consists of

a voltage V ^f ^ _r , which is equal to A (V ^ _n - A-1 El die

^ V λ f

appears on line 118.

The mode of operation of the modified embodiment according to FIG. 6 will now be described below. The amplifiers 115 and 116 in connection with the clamping circuit 117 functionally fulfill the task of an amplifier circuit, the output characteristic of which is illustrated in FIG. This voltage is fed to the cathode of a diode 114 and also to the nqg.tiven input of the comparison stage 97 on the line 118.

In the press mode (C> 1), when V ' _EC suf of line 118 is greater than E on line 50, the comparison stage 97 gives a zero output and the diode 114 is non-conductive, so that the operation in this operating phase is the same is like that discussed earlier with reference to Figure 4A.

In the event that the compression ratio C is less than one, V _{? C} and thereby VVq are each less than E and the output variable of the comparison stage 97 consists of an EIlIS, which sets the NAND gate 110 in readiness, which represents the output variable the comparison stage 98 can control the generation of the reset signal on the line 51.

The reset pulse on the line 51 triggers the reset univibrator 52 so that a reset pulse appears on the line 53 , which controls a gate 111 and puts it in readiness so that it receives the signal from a buffer amplifier

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112 passes when the getter is ready. Gate 111 then passes the output of amplifier 112 so that the reset voltage value for capacitance 91 is established during reset. If V ^ is less than E and the output of the amplifier 112 with a gain of one corresponds to the potential Vn «of the clamp amplifier 115, 116, 117, as indicated in FIG 91 is charged in accordance with the voltage quad V'j-jq on line 112. The modification in the ramp period control is shown in Figure OB, different values of V ¹ ^ _n on the line 118 pI starting point for the * ^A jistieg the ranpen-shaped voltage to the voltage E corresponding to 7.8 volts are indicated. ^T .7enn therefore V-, _n from a ^{T. T} ert off decreases, which equals E, Vr, _c drops rapidly to two volts, which corresponds to a V _EC of about 7 volts and a squeeze ratio of about 0.92 and is then clamped to that value of two volts. The effect of such a change and fixation of the tension is that the sample period for C is limited to close to the unit, in such a way that the gap between the samples for the expansion at the ramp transition point corresponds to that for the compression and the gap with on the two volt ^T ated increases decreasing V'rpp. then (smaller fourth of C) for greater stretch ratios, the gap remains virtually constant, whereas the sample period will vary accordingly. the column v / ground so limited in order exceeding the memory limits in the Line 168 and to accommodate the characteristics of speech perception which require longer samples for continuity, but with the gaps sufficiently short to avoid noticeable, repetitive, or inconsistent filling.

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Those skilled in the art will recognize numerous modifications and changes can be carried out with the system described, without, however, departing from the scope of the present invention. In particular, in the embodiment described described a specific analog shift register as a delay line, but it is obvious is that various other forms of controlled delay elements can be used singly or in combination, which are controlled alternately or on other Tfeise, which also falls within the scope of the invention.

All technical details that can be recognized in the description and shown in the drawings are essential for the invention significant.

409833/0942

* r

Publications related to the subject of the notification:

The present application is based on a "continuation -in-part "application in the USA No. 3 No. 331 550 of February 12, 1973, which in turn is a" continuation-in-part "application in the USA Ser. No. 171 571 - registered on August 13th 1971 - now USA patent 3,786,195 - the content of which is disclosed is hereby incorporated by reference into the present application.

409 833/0942

Claims (11)

PATENT CLAIMS (\ j System for the reproduction of speech or sound signals, in order to have a speech or sound recording played back at a playback speed that is the same as or different from the recording speed, v / whether a means for transporting the speech signal or . Sound signal carrier are provided with a selected playback speed relative to a transducer in order to obtain an electrical SiTial with frequency components which are changed by the ratio C of the playback speed to said recording speed, and wherein the changed frequency components are renewed again so that they are the original C speech signal, characterized in that said electrical signal is converted by a factor of about 1 / C in frequency with a repetitive variable time delay function, the time delay change being set to be a function of C. is dependent on the selected playback speed, where the ratio C- can be in a range of the following values: IIulKC <1, C = 1 and C> 1. ■ 2. System according to claim 1, characterized in that the C-1 function of C is a function of size jrrr . 3. System according to one or more of the preceding claims, characterized in that the frequency conversion is carried out by an analog shift register which has signal input connections and output terminals and a shift signal input; that signal-processing devices are provided in order to 409833/0942 see the signal from the converter to be fed to the output terminal; that further a controllable pulse period square wave generator is provided and coupled to the shift signal input
is to shift signals through the analog shift register at the period of the generator; that a control signal sawtooth generator is also provided
and comprises means for selecting the sign and the slope value of a ramped amirachs terminating control signal so as to thereby produce a repeatable linear change
the ramp-shaped increasing control signal is generated over a range of change, and in order to reset this control signal to a previously determined initial value at the end of the change, whereby a ^T /, ^r repetition interval is determined; that means are provided which the ramp-shaped growing Control signal for controlling the square wave generator so / couple, thereby successively a repetitive change or fluctuation in the period of the square wave generator to generate, the sign and the rate of change being selectable during the T 'repetition interval; that circuit means are coupled to said output terminal in order to receive the signals shifted through the analog shift register, said circuit means operating in such a way that only successive signal sections which lead to the
Output port were shifted during the successive, repetitive • change or fluctuation of the period of the square wave; ; that manually controllable control devices for the selection of the ratio C j by selecting the conveying speed upstream ■ are seen [and that the Se lec the ratio G greater than; 409833/0942 equal to or less than the transport speed can be selected with which the sound or speech on the recording medium was recorded; and that devices are provided which can be actuated by hand Control devices respond to the selected sign and rate of change of the fluctuation or change of the period to relate to the ratio in order to thereby restore the frequency spectrum of the signal sections mentioned to produce that it almost corresponds to that of the recorded sound or speech sign of the recording medium. 4. System according to one of the preceding claims, characterized by a setting of the delay change for Change in the repetition interval of the change or fluctuation for the device responding to the said delay function, the change being almost directly related to the off C + 1 stands. 5. System according to claims 1 to 3, characterized in that the repetition interval of the change for C <1 is essentially is kept constant and in almost direct relationship with C + 1
the expression ^ -y for C> 1 is changed. 6. System according to one or more of the preceding claims, characterized in that blanking devices are provided, to blank the output signal value; that a standby device is provided and near the end of the repetition interval the change or fluctuation of the time delay function is actuated to put the blanking device on standby to set or to release; that a zero crossing detector is provided to detect the zero crossings of the signals detect which is delayed by the time delay function 409833/0942 will; and in that a circuit is provided which is responsive to a detected zero crossing during the period of the release, around the blanking device for a given interval between successive repetitions of the changing To operate the time delay function. 7. System according to claims 1 to 5, characterized by the following devices and features: a detector device for detecting the Uull passage points on the delayed signal; a release or standby device for setting up a release interval on End of each repetitive change in the time delay; and blanking devices responsive to the detection of a passage of gauze respond within the release interval and, if such a zero crossing is not detected, to the Address the end of the release interval to release the delayed signals until after the start of the next repeating change of the specified time delay. 8. System according to claim 7, characterized in that the delay is provided by an analog shift register with a controlled shift period, and that means for Delaying the start of the next repetitive change uni at least such an amount or length is provided, than is necessary for this purpose, the said analog shift register with the input signals that are fed to it, fully closed fill or push. 9. System according to claim 7 or 8, characterized in that the blanking device is responsive to the detection of a Kull passage after the start of the next repetitive change on ^f of said line to terminate the blanking. "409833/0942 ZO 10. System according to claims 1, 2 or 3, characterized in that that the frequency transformation of the speech or sound nigns-Ie to recover the normal frequency spectrum thereof is done by sending the signals through a logic Shift register device are performed, which is controlled with a repetitive change in the shift period, that the above-mentioned analog shift register consists of two identical registers and that the signal section is in one the shift register relative to the signal in derr. - other registers it is inverted that the output variables from the two registers of equal length continue to pass through the shift registers led th. Signals concerns, can be combined additively, and with regard to the particular properties imprinted on these signals combined subtractively by the mode of operation of the registers in such a way that said properties are eliminated in the combined outputs obtained. 11. System according to claims 7, 3 or 9, characterized in that that the following facilities and features are provided: fixed delay memory means connected to receive the signals from the variable delay device for providing a fixed further delay to signals which have been frequency transformed by the variable delay device; and means for connecting the output signals from the variable delay device and the storage device with the fixed delay in accordance with the operation of said gating "" esigned is to form a composite output signal having a blanking interval thereof for the variably delayed Signele with portions signal , which is subject to the further fixed delay mentioned, is filled in » 409833/0942