DE2404282C3 - Device for playing back sound recordings stored at a recording speed of sound carriers at an adjustable playback speed that differs from the recording speed - Google Patents

Description

in that there are purely electronic components in all three Playback areas (('< 1: C = 1: C> 1) a Klanggc-Irene Playback takes place.

Further advantages of the invention can be seen in the fact that the device is cheap to manufacture in comparison with the mechanical devices and can also be retrofitted into existing tape recorders, and that by coupling the change in the time delay to the size of the ratio C, no adjustment is required . since in the worst ("all. ie, fluctuations in the playback speed. pitch fluctuations are automatically compensated for. Another advantage is that the sequence transformation is automatically set correctly in the device according to the invention by setting a single control button for the speed of the drive motor.

In the following the invention is based on a

ini Z'.iSaHimcnhHn ⁰ Πι! ^1st

Drawing described in more detail. It shows

Cig. I a block diagram with details of the Device according to the present invention;

I i g. 2 shows an overall block diagram, with a partly schematic speech compressor and control scarf Depicted for this are shown;

Cig. 2Λ a schematic circuit diagram of the voltage control Period Gcnerators;

Fig. 2B is a signal flow diagram used for explanation the mode of operation of the facility according to E i g. 2Λ serves:

Cig. i is a signal flow diagram of the control device for the blanking switch-on and blanking gate control of the output variable;

E i g. 4Λ a schemaiischcn diagram dc ^r Austasi automatic-power-on and reset circuit:

l'ig. FIG. 4B is a diagram illustrating FIG Operating mode of the saw / hang generator when the pressing period changes:

l'ig. 4C is a diagram to illustrate the Operating mode of the sawtooth generator with an almost constant period for the expansion:

l'ig. 5 shows a block diagram of an additional circuit for filling a gap;

l'ig. 6 shows a modified device according to the Aiisführungsform ^l: ig. 4A to automatically change the repetition period for the stretch:

Cig. 6A shows the working characteristics of the circuit of FIG Cig. fiaind

I i g. bB is a diagram to illustrate the operation of the sawtooth generator using the embodiment of E i g. 6th

Cig. I shows a complete tape player unit. the unit comprises the known recording storage and transport system to store a sound carrier on a Move converter past. to thereby obtain an electrical signal that represents the recorded sound reproduces. In Ci g. I is a pair of coils 11 and 12 to see that contain a magnetic recording tape 13 that moves past a playback head 14! is when the coils 11 and 12 with or without a capstan rub for the tape can be rotated, as is well known. The transducer in the playback head 14 generates an electrical signal on a line 15 Signal corresponding to the sound recorded on tape 13 is equivalent to. The frequency spectrum of the electrical signal on line 15 is determined by the speed determined with which the tape 13 is advanced to the transducer in the playback head 14 and to this / wake up the drive of the coils 11, 12 and / or des Capslan drive for the belt 13 by a motor 16 controlled with variable speed. The speed is determined by a land leveling device 17 is selected and this control device can be set to a (speed range, where Speeds are possible that are equal to, greater or less than the speed at which the Sound recording was originally made on tape 13.

The signal on line 15 passes through a preamplifier equalizer 21. which generates an analog signal with a relatively constant amplitude on line 22, which corresponds to the sound recording. The signal on the line 22 passes through a voltage converter processor 23 which is controlled by a control circuit 24. As a result, the frequency range of the signals on line 22 is in a. Speech frequency range on / lor I oitiiniT 0 \ I pincfr »rn-» inrt Dj * ¹ ^ ΪΠ'.ΉΓί ^ ίϊ ^ Π Ί ° Γ Circuits 23 and 24 are described below described in more detail.

The frequency transformed signal on line 25 is amplified for playback in an amplifier 26 which has the usual volume control 27 and Sound control device 28 may have, and is further fed to a blanking control device 29 to on line 31 to generate an output signal which is converted into an audible signal through a loudspeaker 32 is converted. In order to coordinate the operation of the device so that the frequency transformation corresponds to that required for the speed selected for the motor is the manual control device 17 also coupled at 33. As a result, the control circuit 24 and thus the Frequency processor 23 controlled, whereby the desired frequency transformation of the signals that processed by the unit 23 is made possible.

In the following, with reference to FIG. 2, the general arrangement or construction of the frequency processor 23 and the control circuit 24 is described will.

The motor speed can be selected via the manual control device 17 with the aid of a motor control circuit 44. The motor control circuit 44 also provides, in dependence on the setting of C, an output signal which is fed to an f (c) circuit 45 which enables the linear setting of C on the hand control device 17 to a voltage of a

Line 41 converts, which here the function K -

obeys, as the functional relationship to building the slope of the sawtooth or the sawtooth voltage as a function of the ratio C.

A delay, which is a continuous, time-linear function with a slope d during the entire sampling period, leads to the desired frequencies - I
transformation, where d = 2 - ■ .

For an incremental delay, as is obtained with analog shift registers that are controlled by shift pulses with a geometrically increasing period, this relationship provides ^{an exact frequency transformation for the 7 (r} c _/ ^L function for the instantaneous incremental delay d , in particular for mean values of C Wherever large compression or expansion values are desired (for example C <03 or C> 2.0), read a

more precise function for d. which also takes increasing quantization deviations into account, as follows:

C- I

This input variable on line 41 to a sawtooth generator 42 generates a sawtooth voltage on an output line 46, the slope of which is determined by the input voltage on line 41 reset, whereby the repetition interval of the sawtooth voltage is determined r>. The period duration of the sawtooth voltage decreases with increasing slope. For a ratio of C that is greater than one. This direction, in order to build up the voltage on the capacitor 58. The control of the generator 57 takes place according to a function V /, which has the form of an on or off signal and comes from the output 60 of a flip-flop 59. The state of the flip-flop 59 is caused by the output variables of two voltage comparison stages 61 and 62, which each receive the voltage Vr as input variables from the capacitor 58. The comparison stage 61 receives a voltage as a further input variable E which has a fixed predetermined value. The other input of the comparison stage 62 is supplied with the input voltage V ₍ from the sawtooth generator 42. The fixed voltage E is always greater than the input voltage V ₁ .

The mode of operation of the circuit of FIG. 2A is explained with reference to the diagram of FIG. 2B explained, where the constant voltage E is shown and it can be seen that the discharge current / ι causes the

g Come άϋιιι 111Γ rrcTic Vufi «_ uciuciiüiicii

that are smaller than one, as will be explained in more detail below m.

A voltage Vf _f ■ on the line 41 is fed via a line 47 to a blanking enable circuit 43 which determines whether the unit is operating in compression or expansion mode, which can be determined by comparing the voltage on the line 47 with a fixed value, such as 7, 8 volts, happens. If the voltage on the line 47 is above 7.8 volts, the device compresses the speech for a C greater than one and for this condition the Ausust enable circuit 43 produces two outputs when the sawtooth voltage reaches its final value of 2 volts. By sampling an input variable on line 48, i.e. from the output of sawtooth generator 42 on line 46, blanking enable circuit 43 generates a blanking enable signal on line 49 when the input variable on line 48 reaches the value of 3 volts, and generates a reset signal on line 51 when the signal on line 48 reaches the value of 2 volts which is the designated end of the sawtooth period when the end of the sawtooth period. When the sawtooth value has now reached 2 volts, a reset pulse on line 51 triggers a monostable multivibrator 52, hereinafter referred to as monoflop, which is connected to line 53. This resets the sawtooth generator 42. At the end of the reset pulse of the monoflop 52, which resets the sawtooth generator 42 to 73 volts, starts the next sawtooth deflection. The length or duration of the reset pulse of the monostable multivibrator 52 is sufficiently long that the sawtooth generator can be reset to 73 volts as the starting point.

The output variable Vc of the sawtooth generator 42 is fed to a voltage-controlled period generator 54 which generates a square-wave output variable on a line 55, the pulse period of which changes linearly with the linear change in the sawtooth voltage Vc . 2A. This consists of a current generator 56 which generates a current / ι and a current generator 57 which selectively generates a current 2 / t in the opposite direction, both currents being used to charge a capacitor 58 and discharge it. The current Tj of the generator 56 flows continuously, and the current 27i through the generator 57 selectively flows in the opposite ομαιιιιιιιΐ £ all ucill nuiiuciiaaiui -ro nut ciiici ituiisiauicii The speed drops, as indicated at 63, until the voltage value Vc is reached. The output variable Vy then switches on the current from the generator 57 and the current 2 / i charges the capacitor 58 in accordance with the curve 64. The slopes 63 and 64 are oppositely equal, since the charging current 21, twice the value of the charging current I, has. As soon as the voltage 64 reaches the value £, the flip-flop 59 changes its state. This removes V _F as a control voltage, which interrupts the generation of 2 / t in the current generator 57. This process is repeated as shown in FIG. 2B, and with a linearly changing input voltage Vc, the period of the control waveform Vf is, as shown, a succession of square waves, the period of which increases linearly with time. This output variable Vf reaches the line 55 as the output variable of the voltage-controlled period generator 54. Typically, the shift period with 256 shift levels for a storage delay, as corresponds to the exemplary embodiment selected here, can fluctuate between 4 μs and 62.5 μ5.

For a stretching or expansion, the stress curves in FIG. 2B modified in such a way that the slope of Vc is positive and the beginning occurs at the minimum value of V _p. These conditions in the circuit of FIG. 2A lead to output pulse signals Vf, the width of which is initially a maximum, and their period duration decreases linearly with the time between the end points, which were explained earlier

The output on line 55 is fed to a phase splitter driver circuit 65 which is an Outputs 66 and 67 square waves in antiphase generates the square wave input variable on the Line 55 correspond to the Φι-, Φϊ-ΤΓβΗιβ ^ οΒεη are to convert the analog signals through a pair of analog Shift registers 68 and 69 with 256 storage stages.

The shift registers 68 and 69 are connected for the elimination of signal processing interference factors by operating the units at a changing shift pulse period. For this purpose the audio signal appears on line 22 from preamplifier 21 in FIG. 1 am Input terminal 71 of an amplifier 72, the output of which is connected to the input of the analog shift register 68 and to an inverter 73 The output variable of the inverter 73 is used as an input

signal to the analog shift register 69. The output variables of the shift registers 68 and 69 arrive as subtractive input variables to a differential amplifier unit at the input of an Audion amplifier unit 74.

The circuit previously described that controls the shift register 68 and 69, the amplifier 71 and the inverter stage 72 together with the differential amplifier 74, carries out the frequency transformation of the input signal on line 71 and also ensures at the same time an elimination of the disturbances and distortion influences caused by the processing of the signal the shift registers 68 and 69 were introduced.

In the amplifier 74 is further the difference signal, obtained by connecting the two inputs from the shift registers 68, 69 is amplified and the amplified audio signal appears on line 25. In unit 74 is also a zero crossing detector determined is caused! the reset signal supplied to counter 81 on line 83 immediately the occurrence of a blanking signal on line 78, which goes to circuit 76 to power audio amplifier 74 by a suitable signal on line 77 to feel. The action of counter 81 removes the signal on line 78 to provide the blanking signal on line 77 at the end of the 256 pulse count on line 82. the Audio output will therefore be plus for the duration of the reset univibrator 52 output pulse the period required to count 256 counts in counter 81 plus the time interval the end of the 256th counting step for the detection of the next signal zero crossing, blanked.

The blanking / non-blanking control logic 76 contains a D flip-flop which ^{controls its output variable via inputs on lines 49, 75} and 78, as in FIG. 3

cimiaiicii, uci aui

Ulli «. IWIlM- VWII

Generates pulses that reflect the times of the zero crossing of the difference signal.

A blanking-not-blanking control circuit 76 receives the zero crossing pulses on line 75 and operates when it has been set to standby by the blanking enable signal on line 49 and then generates a blanking signal on line 77, through which the output of audio amplifier 74 is blanked. This arrangement enables the value of the output signal on line 25 during the reset period for the shift registers and the controlled sections of the sawtooth generator the circuit can be sampled to a signal level of zero. The circuit 76 responds Signal on line 78 to terminate the blanking signal on line 77, causing the signal on the Line 25 is given the opportunity to return to its signal value.

At the end of the 256 counting steps, a counter 81 supplies an output variable on the line 78, these counting steps corresponding to the length of the individual registers 68, 69. The counter responds to the impulses on the line 55, which are given in the meter . When the counter 81 has counted 256 input pulses on the line 82, it generates an output variable on the line 78, by means of which the blanking period pulse on the line 77 is terminated. An output pulse similar to the pulse appearing on line 53 appears on line 83 and resets counter 81. The interval determined by the counter 81 when counting 256 pulse signals on the line 55 leads to a blanking period for the amplifier 74 which is sufficient for the pulses on the line 55, after they have passed through the driver stages 65, to the registers 68,69 to shift and read out their contents before the blanking stops and the audio output variable appears again on the line 25 so that the registers 68, 69 are filled at the end of the blanking interval and are ready to feed audio samples to the input of the amplifier 74 and the next signal period can occur.

In the event that no zero crossing signal occurs on line 75 during the standby period, that shown by the signal on line 49 prior to the occurrence of the reset signal on line 51 . l / cF rTcigäucciMgäiig ^ i ^ citüiig Τ7 /

jit blanking after the occurrence of a zero crossing within the release interval and if this does not take place, the pulse of the reset monoflop forces on line 83 the beginning of the blanking interval by a signal on line 78, which during

j> of 256 counts in counter 81 lasts. At the At the end of the 256 counting steps, the signal on line 78 enables the blanking signal to be removed Occurrence of the next zero crossing detection signal on line 75, this serving to detect the

jo output variable on line 77 to switch.

To the monoflop 52 before the saw voltage end signal on line 51 and in synchronization with upon detection of a zero crossing by the blanking control unit 76, the signal on the

jj line 77 fed to a pulse generator 101 which the monoflop 52 resets after the occurrence of an output signal on the line 77. The output size When the monoflop 52 is reset on the line 53, the sawtooth generator 42 is thus set back coincides with the detection of the first zero crossing after the blanking clearance ··; and the Frsoheinpn pinp «; «Mlnhpn .Sicmals on line 77. Up this way the gap in the audio output signal is reduced by a substantial amount in all cases, except if no zero crossing is detected during the full duration of the blanking enable signal became.

For the time expansion, i.e. H. in the event that C is less than one, the voltage signal on line 47,

so that the blanking enable unit 73 is supplied, compared with the voltage E on the line 50, which is 7.8 volts, in order to produce a sawtooth voltage with an opposite slope and with a substantially constant repetition interval of the sawtooth generator 42. A blanking enable signal is also generated on line 49 when the ramp voltage reaches its final value of 7.8 volts and the final reset pulse is generated on line 51 as described

With reference to F i g. 4A shows the structure of the sawtooth generator 42, the blanking enable unit 43 and the reset monoflop 52 and their relationship to one another will be described in detail. In F i g. 4A belongs to the section on the left of the

* -> dashed line in general to the sawtooth generator 42, which is shown in FIG. 2 and relates to the portion to the right of the dashed line generally the units 43 and 52 of FIG. Of the

Saw-tooth generator 42 essentially contains a capacitor 91 which is supplied by a constant current source 92 and from a pin variable current source 93. The current from source 92 charges capacitor 91 and the current from source 93 discharges it. The source 93 is voltage controlled by the voltage Vu on the line 47 so that when the signal Vn is equal to the value E , the current discharge rate through the source 93 is equal to the current charge rate from the source 92, so that on the capacitor 91 no voltage change occurs. 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 capacitor 91. The voltage across the capacitor 91 therefore consists of a positively or negatively increasing sawtooth voltage, the sign of the slope being determined by the relative quantities Vn and E and the value of the slope tiw. Slope is determined by the size difference. This ramp-shaped voltage appears as an output variable on the line 46 in order to supply the input variable to the voltage-controlled period generator 54, as has already been described earlier.

For time compression, the value of C is greater than one and the voltage Vn is greater than the voltage E and has a value determined by the selected value of the compression ratio C and further by the voltage analogous to this setting made by the motor control circuit 44, generated modified by the function circuit 45, is determined.

A number of voltage comparison stages 94, 95, 96 , 97 and 98 are provided to control the sawtooth voltage. The property of the comparison stages 94-98 is to provide a "ONE" output variable if the plus input variable is greater than the minus input variable, and a "ZERO" output variable for the opposite condition. The sawtooth voltage of the capacitor 91 is fed to the negative input connections of the comparison stages 94, 95 and 96 and 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 «- is fed to the negative input of the comparison stage 97 and a voltage between V _E c and the voltage E is fed to the positive input of the comparison stage 96, with the help of a voltage divider that connects the lines 47 and 50 to the positive input of the Comparison stage 96 connects, which is connected to the connection point of this voltage divider. The comparison stage 94 receives an input value of +2 volts at its positive terminal and the comparison stage 95 receives an input value of +3VoIl at its positive terminal. The outputs of the comparison stages 94-98 are in logic Link »NAND« circuits (105-110) ops, which generates 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 obtained from the NAND gate 105 , which receives the inputs from the comparison stage 96 and the NAND gate 106. The NAND gate 106 receives inputs from the comparison stage 95 and from an inverter stage 107, which at its input the output of the comparison stage 97 receives.

The reset pulse on line 51 is tapped from the output of NAND gate 108 , the

■> The input variables for this gate come from the outputs of the NAND gates 109 and 110 . The input variables to the NAND gate 109 come from the output of the inverter stage 107 and the output of the comparison stage 94. The input variables to the NAND

Gates 110 come from the outputs of the comparison stages 97 and 98.

The reset pulse on line 51 triggers the reset monoflop 52 in such a way that it is on line 53 a reset pulse generated which a gate 111 in the

π controls the conductive state, so that a signal from a buffer amplifier 112 can pass through this gate when this gate is set to standby. The output variable from an amplifier 112 then appears at the output of the gate 111 , so that

2Ii thereby the reset voltage value for the capacitor 91 is built up during the reset. The voltage to which capacitor 91 is reset is determined by the relative magnitudes of Vn and E. If Vec is greater than E, it becomes dem

r 112 voltage supplied by the line 50 to the potential êabove tapped> input of the amplifier 113 and the resistance effected thereby is greater than unity for Preßverhältnisse reset to a constant voltage value E. If Vn is less than £ is a

jo diode 1 14 is biased into the conducting state and the input of the amplifier 112 corresponds to the potential Vn; thereby charging capacitor 91 to the variable voltage level established by Vfc on line 47.

r> In the following, with reference to the waveforms of FIG. 4B, the mode of operation of the circuit of FIG. 4A explained for a time compression, ie for C> 1. The voltage Vn is greater than the voltage f, so that the comparison stage 97 thereby generates the output variable "zero" and the NAND gate 110 is blocked. The output variable of the comparison stage 98 thus does not influence the generation of the reset signal on the line 51. The inverter stage 107 leads to a "one" at its output, whereby the N AND 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 capacitor 91 falls below the value of +2 volts at the input of the comparison stage 54.

So the output variable of the inverter stage 107 has also set the NAND gate 106 in readiness at this point in time and thereby the output variable of the comparison stage 95 controls the NAND gate 105, which generates the blanking enable pulse on the line 49 when the voltage on the capacitor 91 falls the value of +3 volts drops. The output of NAND gate 96 performs a "one", since the voltage Egrößer than the voltage on the capacitor 91 for all values of Vec larger than E a result, the charging speed of the capacitor is changed by the voltage Vec 91, the reset and However, blanking enable signals are generated with a constant voltage value of 2 and 3 volts, as shown in FIG. 4B, the resulting change in the repetition period of the sawtooth voltage, i.e. when it falls from 7.8 volts to 3 and 2 Voits with the different slopes, is determined by Vec . For very small press ratios, greater than one, the period is very long and they

is gradually reduced to approx. 30 ms fü. C = 2 and to 20 ms for C = 3 as typical values. Since V «determines the slope or slope of the sawtooth voltage, the

is roughly proportional to the expression ^ ₍ , the period for C> \ is roughly proportional to the expression A typical value for the period is

For C = I, Vn is equal to E and the charging and discharging currents of the capacitance 91 are the same. The voltage on the capacitor 91 remains constant, whereby the slope of the sawtooth voltage becomes zero, which leads to a fixed delay, whereby no frequency transformation takes place in the analog shift registers

In the event that the compression ratio C is less than one, Vec is also less than E and the output of the comparison stage 97 carries a "one", whereby the NAND gate 110 is set in readiness so that the output of the comparison stage 98 can generate the Reset signal on line Sl can control. The output of the inverter stage 107 drives a "zero", whereby the NAND gates 106 and 109 are set out of readiness. For the case that the voltage on the capacitor 91 is greater than ER (! ■ -Vec) · where the constant R, which is determined by the voltage divider to which the positive input of the comparison stage 96 is connected, can be almost 0.1 , the output variable of the comparison stage 96 becomes a "zero" and a blanking enable signal is generated on the line 49 by the NAND gate 105. When the voltage of the capacitor 91 reaches the end of the sawtooth voltage at £ ", the output of the comparison stage 98 carries a" one ", as a result of which a reset pulse is generated on the line 51 via the NAND gates 110 and 108. This mode of operation is shown in FIG 4C, with various values of V _{FC being shown} as the starting point for the sawtooth voltage, which rises to the voltage £ of 7.8 volts. The quantity ER (E-Vec) changes somewhat with the value of Vec, whereby the blanking enable point on the sawtooth 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 device shown is 40-50 ms.

In certain applications, especially in the case of speech expansion, it is useful to reduce the interference caused by the gaps which result from the blanking between the samples, which can be done by dropping the gaps with a corresponding signal. In the following, it is intended to refer to FIG. 5, which shows the general arrangement of additional functional components required to fill said columns with slightly delayed portions of the processed signal. The signal from the audio output on line 25 of FIG. 2 is fed to a biasing network 172 and there arrives at an analog delay line 168. A square-wave signal 153 with a constant frequency, which comes from a generator 152, generates complementary driver signals with a constant frequency Lines 167 and 166, causing the signal on delay line 168 to be delayed by a fixed amount at the output on line 151.

The output 78 of the counter 81 of FIG. 2 starts Flip-flop 176 is ready at its D terminal, so that this is a gate control signal on line 177 outputs, in which each change of state is triggered by a ι zero crossing pulse 175 of the detector 174 will. The aforementioned gate control signal 177 is used to delayed audio signal 151 between a beginning and an ending zero crossing during the Blanking interval of the applied processed signal

in 25 not to be blanked. The resulting gated delayed signal which is appropriately in the Amplifier 174 is normalized, then with the basic processed signal on line 25 connected in a summing amplifier 148 to a

ι ί composite audio signal on line 150 too produce.

F i g. 6 shows a modified embodiment of the object of FIG. 4A, which is more suitable for the Spa-fill expansion is clamp amplifier circuits 115, 116 and 117 have been added here to change the property of the sawtooth reset during the stretching operation (C <\) so that a change in the period as a function of the pressing ratio C as for the pressing operation (C> 1) is possible, however, a smooth transition should still be maintained when changing from stretching (C < 1) to compression (C> 1) and vice versa. For this purpose, the voltage E on line 50 is used as an input variable for the amplifier

^Λ) 116 supplied, which has a gain of —- ^ - and whose output is connected to the negative input of a differential amplifier 115. The positive input of amplifier 115 consists of the voltage Vec derived from js line 47. The output of amplifier 115 consists of a voltage VfCf which is equal to

appearing on line 118

In the following, the mode of operation of the modified embodiment according to Fig.6 be be written. The amplifiers 115 and 116 meet in connection with the clamping circuit 117 is functional the task of an amplifier circuit, the output characteristic of which is shown in FIG. 6A Voltage is applied across line 118 to the cathode

Diode 114 is supplied and continues to the negative input of the comparison stage 97.

In the pressing operation (C> 1), when Vorauf on line 118 is greater than E on line 50, the comparison stage 97 drives a "zero" and at its output the diode 114 is non-conductive, so that the operation in this operating phase is the same as that in FIG. 4A circuit shown is

In the event that the compression ratio is less than Eint, Vr: and thereby V'ar are each less than / Tund

go the output of the comparison stage 97 drives a “one”, which sets the NAND gate 110 to readiness so that the output variable of the comparison stage 91 can control the generation of the reset signal on the line 51.

The reset pulse on line 51 triggers this

Rückstell'Monoflop 52, so that on line 53 a Reset pulse appears that controls a gate 111 and sets this in readiness so that it receives the signal from a buffer amplifier 112 passes. The gate

111 then passes the output of amplifier 112 so that the reset voltage value for capacitor 91 is built up during reset. When Vt c is less than and the output of unity gain amplifier 112 corresponds to the potential V'fr of clamp amplifier 115,116,117 as indicated in Figure 6A, diode 114 is forward biased, thereby causing capacitor 91 to correspond to the voltage level V'ec on line 112 is charged. The modification of the sawtooth period control is shown in FIG. 6B, with various values of V'er being indicated on the line 118 as the starting point for the rise of the sawtooth voltage to the voltage E, corresponding to 7.8 volts. Thus, as Wc decreases from a value equal to E , V'ec drops rapidly to 2 volts, which corresponds to Vfc of about 7 volts and a compression ratio of about 0.92, and then becomes that value of two Volt Latched The effect of changing and locking the voltage in this way is to limit the sample period for C close to equality such that the gap between samples for elongation at the sawtooth transition point equals that for compression and the gap with on the two Volt value as V'ec increases. Thereafter, for larger expansion ratios (smaller values of C) , the gap remains almost constant, while the sampling period fluctuates accordingly. The gaps are limited so as to avoid exceeding the memory limit in the line 168 and to avoid the? To meet the requirements of speech perception, which requires longer samples for reasons of continuity, but with the gaps sufficiently short to avoid perceptible, repetitive or inconsistent filling.

Those skilled in the art will recognize that a number of modifications and changes can be made to the aforesaid System can be made without, however, the scope of the present invention leaving. In particular, a specific analog shift register was used in the described embodiment described as a delay line, however, it will be apparent that various others Forms of controlled delay elements can be used individually or in combination, the alternately or otherwise controlled.

In summary, the invention provides a speech compressor and expander employing a sawtooth generator controls a voltage controlled period generator to generate a square wave signal whose Period is linearly variable, so that thereby the shift period of analog shift registers is controlled in which the frequency transformation is carried out. The facility to control the Motor speed and the sawtooth generator are controlled by a single hand control device set, whereby the compression or expansion ratio is set and whereby the Speed at which the motor is running is coordinated with the slope of the sawtooth, and ultimately the change sequence of the linear period change of the

ίο square wave generator, creating the desired Frequency transformation for the recovery of the normal frequency spectrum of the audio or speech signals is achieved. When the signals pass through the analog shift registers, they become the Signals delaying registers are separated into two equal sections and the signals are passed through the two Halves of the analog shift register are shifted, taking for signals passing through one half of the Register pass through, a signal reversal is made. The signals are from the Outputs of the two halves of the register tapped and combined with one another, either one behind the other or in parallel. The interfering component caused by the processing, which is caused by the supply of the linearly variable square wave as a shift period for the registers is caused by a Inversion technique eliminates while the sound signal components are added, thereby increasing the signal value is improved and the value of the processing noise component is greatly reduced. At the end of periodic change in the delay of the shift register is a zero-crossing demodulation at the Signal made and the tone output will be during the resetting of the sawtooth voltage and

J5 of the control period generator during the deletion of the signal stored there and during the period reloading the register before the output signal reappears on the output terminals blanked In addition, the present invention provides improved control of the repetitive sampling periods achieved, whereby the relation of the obtained sample and the Deletion time with the properties of human speech and the selected compression or Expansion ratio is optimally designed. Finally, a signal memory is used to fill in the Time interval used during the reset, this storage being especially during the Stretching is useful when the gap in the

so output signal at low expansion ratios may be undesirable for other reasons.

For this purpose 3 sheets of drawings

Claims (11)

Patent claims: 1. Device for playing back sound recordings stored on sound carriers at a> recording speed with an adjustable playback speed different from the recording speed, the sound carrier being moved at the playback speed past a transducer which generates electrical signals corresponding to the sound recordings stored on the sound carrier, whereby these electrical signals are fed to a device in which their frequency is transformed according to the reciprocal value ι ί (1 / Q of the ratio C of playback speed to recording speed, so that the pitch of the played sound recording is equal to the pitch of the recorded sound recording, the ratio C can lie in the following ranges: 0 <C <1; C = I; C> \, characterized in that the device contains a time delay device (68,69) which changes the signals with a repetitive and time-proportional change n time delay delayed, where the change in time delay is a function of the ratio C. 2. Apparatus according to claim 1, characterized in that the function of the ratio of C so the equation ~ -—r obeys. 3. Device according to claims I or 2, wherein the Zeitverzögerungscinric ^ device of shift registers with signal inputs, outputs and a shift clock input for each J5, characterized in that that a controllable period generator (54) connected to the shift clock input is provided that generates the shift clock signals that a with the input of the period generator (54) connected sawtooth generator (42) is provided, the sawtooth-shaped output voltage is adjustable with regard to sign, slope and repetition duration, whereby the change in Time delay of the sawtooth output voltage corresponds, the period duration of the period generator (54) proportional to the output voltage of the sawtooth generator (42), and where the sign, slope and repetition time the sawtooth-shaped output voltage of the sawtooth generator (42) over the playback speed are adjustable, and that the output signals of the shift register (68, 69) receiving Audio amplifier and zero crossing detector (74) is provided, which only successive signal sections, which are shifted through one of the shift registers during a sawtooth period, evaluates. 4. Device according to one of claims 1 to 3, characterized by one on the setting of the wi Change of the device responding to the time delay (Fig. 4A, 91), whereby the change in is directly related to the expression ^. 5. Device according to claims 1 to 3, t, -, characterized in that the repetition interval of the change in the time delay for C '< I is essentially constant and for C> 1 in direct Relationship with the expression,, is changed. 6. Device according to one of claims 1 to 5, characterized in that blanking devices (76) are provided which blank the output signals of the audio amplifier (74); that a blanking enable device (43) provided that near the end of the repetition interval of the Andes mg of the Time delay enables the blanker (76) to standby; that a zero crossing detector (74) is provided, which detects the zero crossings of the signals caused by the time delay function be delayed; and that a circuit (77) is provided which is responsive to a detected zero crossing during the period of the release responds to the blanking device (76) for a given interval between successive iterations of the changing time delay function actuate. 7. Device according to claims 1 to 5, characterized in that a Nuüdurehgangsdetektor (74) is provided, which detects the zero crossings of the delayed signals, that a blanking release device (43) is provided at the end of each repetitive change in the time delay a release interval generated, and that blanking devices (76) are provided which on address the detection of a zero crossing within the release interval and if such a gauze passage is not detected, respond to the end of the release interval to the delayed signals until after the start of the next repetitive change in the time delay to feel. 8. Apparatus according to claim 7, characterized in that the delay by an analog Shift register (168) is provided with a controlled shift period, and that means (81) to delay the start -the next oneself repetitive change is provided by at least such a period of time as required for this is to fill the analog shift register with the input signals to be fed to it. 9. Device according to claims 7 or 8, characterized in that the blanking device (76) on the detection of a zero crossing after the start of the next repetitive change responds to the termination of the blanking. 10. Device according to claims 1, 2 or 3, characterized in that the analog shift registers consist of two registers of equal length (68, 69) exist and that the signal section in one of the shift registers relative to the signal in the other register is inverted so that the output variables from the two registers of equal length (68,69) a differential amplifier (74). 11. Device according to claims 7, 8 or 9, characterized in that a fixed delay memory device (168) is provided which receives the frequency-transformed signals and delayed by a fixed amount of time, and that one Means (148) is provided which the frequency-transformed signals and the output signals from the memory device (168) with a fixed delay as a function of the output signals the blanking device (76) interconnects to produce a composite output signal to form whose blanking interval for the changeably delayed signals with sections of the same signal that are further fixed Delay is delayed, is filled out. The invention relates to a device for playing back sound recordings stored at a recording speed on n> sound carriers with an adjustable playback speed different from the dsr recording speed, the sound carrier being moved at the playback speed past a transducer which has electrical sound recordings corresponding to the sound recordings stored on the sound carrier ι ϊ Signals generated, these electrical signals are fed to a device in which they are transformed in frequency according to the reciprocal value (MC) of the ratio C of playback speed to recording speed, so that the pitch of the reproduced sound recording is the same is the pitch of the recorded sound recording, where the ratio C can be in the following ranges: 0 < C < 1; C = 1; C> 1. 2> If the playback speed is faster than the recording speed (C> \), time will be pressed and the information will be played back in a shorter time than it was recorded. Conversely, if the playback speed is slower than the recording speed (C < 1), the time is stretched and the information is reproduced in a longer period of time than was necessary for the recording. Devices that can perform this time compression or expansion are also referred to as "speech compressors" or "speech expander", whereby of course not only speech signals but also signals in general that contain information are "pressed" or " stretched "-" being able to ground. From the magazine "Electronic Rundschau", No. 8/1958, pages 275 to 276, as well as from the magazine »Elektro-Technik«, No. 17, April 27, 1957, page 139, is one Device for changing the playback time of a sound recording has become known in which the pitch the reproduced sound recording is transformed so that it matches the pitch of the recorded Sound recording is identical. The frequency transformation is done by a rotating sound head made, on the egg. Scope of several scanning devices or transducers are attached. The single ones Wand'er move with a relative speed compared to the sound carrier, here a tape, this relative speed being equal to the relative speed between the sound carrier and the sound head the recording is. The playback time depends on the speed of movement of the sound carrier dependent, while the required frequency transformation is carried out by the rotating sound head will. With these electromechanical devices <, o both speech compression and Speech expansion can be carried out. However, these electromechanical devices require high-precision drives for the sound carrier movement and the head movement. A subsequent attachment to an existing tape recorder requires a elaborate, expensive ur.ii also in terms of space requirements considerable construction, which due to its mechanical Components require regular maintenance. From US-PS 36 21 150 a device of the above type has become known, which works purely electronically, ie without additional mechanically moving components. For this purpose, the signals sampled from a sound head are digitized in an analog-to-digital converter and alternately entered into two shift registers at the frequency of a clock generator. The information is alternately shifted out of the two registers via a second clock generator, the frequency of which is different from that of the first clock generator, one register being loaded while the other register is unloaded. The register from which the information is to be shifted is selected using a switch. The unselected register which is loaded at this time phase, in this case so that remaining information remains verden output side "open", pushed out without being evaluated. The ratio of the frequency transformation is determined here via the ratio of the frequencies of the two clock generators. The frequency transformation is carried out according to the reciprocal value (MC) of the ratio C of recording speed to playback speed. The ratio of the frequencies of the two clock generators is freely adjustable. Should this device work as a speech expander, the incoming signals have to be clocked into the register with a lower frequency and with a higher frequency Frequency can be clocked out of them. For example, at a frequency ratio of 2, during one Time period into the first register with the low frequency e.g. B. 3 pulses clocked in, while in the the next time period of the same length with the high frequency 6 pulses are read out. There in In the first register, however, only 3 positions are occupied, there is an information-free gap of three Register places on. This results in a thoroughly audible gap that allows the sound to be reproduced in one would distort to such an extent that a lifelike reproduction, corresponding to the recording, is no longer possible given is. Furthermore, an adjustment of this known device is difficult because the belt speed and the two frequencies of the two clock generators are set independently of one another must be done, which can only be done with precise measuring instruments, since the human ear - except for people with perfect pitch - is not able to deviate from the real one Determine the pitch. Furthermore, an initial adjustment, for example the Frequency of one of the generators are lost, so that impermissibly large frequency shifts occur. The object of the present invention is therefore to provide a purely electronically operating device of the above Art to improve so that in the three possible display areas, i. H. Expansion, same Speed and compression, a lifelike reproduction takes place without any information gaps appear. This object is achieved by the features specified in the characterizing part of claim 1. Beneficial Refinements and developments of the invention can be found in the subclaims. The main advantage of the present invention is