RU1795561C - Device for freguency companding of sound signals - Google Patents

Description

an amplifier, a fifth frequency divider and a fifth channel low-pass filter included between the fifth input of the channel multiplexer and an additional output of a third frequency divider, the input of which is connected to an additional output of the first frequency divider, and the output of the fourth channel low-pass filter is connected to the second input of the second subtractor, a third pulse shaper, a first sampling and storage unit, a first low-pass filter and a subtractor, a first input are introduced in series into each frequency divider which is an additional output of the frequency divider, and the second input is combined with the second input of the sampling and storage unit and the input of the extremator, the fourth pulse former, the second sampling and storage unit, the second low-pass filter, the output of which is connected to the control inputs of the first , of the second and third controlled root extractors combined with the second input of the first adder, the output of the first controlled root extractor is connected to the input of the first inverter, the control input the first inverter is combined with the input of the third pulse shaper and connected to the second output of the comparator, the first output of which is connected to the input of the fourth shaper, the second input of the first root extractor is combined with another input of the second sampling and storage unit, and connected to the output of the subtractor, and the second and third controlled root extractors are connected between the outputs and inputs of the corresponding first and second adders and the second and third inverters, and on the receiving side the first subtractor is inserted, included between new and additional outputs of the first frequency multiplier and the input of the first attenuator, the second frequency multiplier and the output adder connected in series between the output of the first adder and the input of the amplitude low-frequency corrector, the second phase corrector, the second adder and the third frequency multiplier connected between the third output of the unit dividing the channels and the second input of the output adder, connected in series with a fourth frequency multiplier, a second subtractor, and a second attenuator, connected by the fourth output of the channel separation unit and the second input of the second adder, and serially connected to a third phase corrector, a fifth frequency multiplier and a third attenuator.

connected between the fifth output of the channel separation unit and the third input of the output adder, an additional output of the fourth frequency multiplier is connected to

the second input of the second subtractor, in each frequency multiplier, a series-connected squaring unit and a follow-up detector are inserted, the output of which is connected to the control input of the unit

squaring, the input of which is connected to the output of the second frequency doubler, the input and output of the servo detector being the main and additional outputs of the frequency multiplier, respectively, a squareing block included in the input of the frequency doubler and the next a detector whose input and output are connected to the inputs of the subtractor and to the output and

0 is the control input of the squaring unit.

2. The device according to claim 1, characterized in that each controlled root extractor contains a sequentially connected operational amplifier, the diode and root extractor of which the output is the output of a controlled root extractor between the input of which is connected to the operational amplifier and its output

0, a squaring unit is included, the control input of which is the control input. controlled root extractor.

3. The device according to p. 1, characterized in that 5 each low-pass filter contains two series-connected active integrators and a resistive voltage divider, the input of which is connected to the output of the second integrator, which is the output of the low-pass filter, and the common point of the resistance divider is connected to the non-inverting input of the first active integrator, the inverting input of which is the input of the low-pass filter 5.

4. The device according to claim 1, wherein the delay unit comprises a series-connected controlled light source, the input of which is

0 by the input of the delay unit, a photoresistor, a load resistor, an amplitude-frequency corrector, and an amplifier, the control input of which is connected to the load resistor, and the output is the output of the delay unit.

5 5. The device according to claim 1, characterized in that the following amplitude detector comprises a series-connected extremator, a comparator, a pulse shaper, a sampling and storage unit and a low-pass filter, the output of which is. the output of the next amplitude detector, the input of which is the combined inputs of the sampling and storage unit and the extremator.

The invention relates to radio engineering and communication and can be used in high-quality audio signal transmission systems via a significantly narrower than standard communication channel.

At present, this problem is mainly solved only with the help of half-coders, but they have limited application possibilities due to significant distortions of the resulting signal.

According to the principle of operation, the known Wobank system is similar to the proposed device, but it introduces even more distortion into the resulting signal.

Closest to the proposed device is a frequency compander of audio signals, which on the transmitting side on the transmitting side contains a series-connected input low-pass filter (LPF), an amplitude high-frequency (HF) corrector, a frequency compressor containing one control channel, consisting of a peak detector and a low-pass filter and N conversion channels, a channel compression unit and a bandpass filter (PF). Each compressor channel contains a high-pass filter (HPF) connected in series, an amplifier that is not in the first channel, a frequency divider (RF), and a channel low-pass filter, the output of which is connected to one of the inputs of the channel compaction unit. The HPF input of the subsequent channel is connected to the RF output of the previous channel.

“The receiving part of this device contains a series-connected channel separation unit, a frequency expander consisting of N conversion channels, the input of each of which is connected to one of the outputs of the channel compression unit, an amplitude low-frequency (LF) corrector and an output low-pass filter. Each expander channel contains a phase corrector connected in series, an adder that is absent in the last channel, a frequency multiplier (UCH) and an attenuator that is absent in the first channel. The attenuator output of the subsequent channel is connected to another adder input of the previous channel.

The PM in this device contains an extremator. a voltage comparator and several series-connected two-phase motors, two, the first of which contains an adder.

a counting trigger, two analog keys and a subtracter, and the rest - the first PM for two, an additional counting trigger and a shaper of short pulses.

The UCH contains the same number of series-connected frequency doublers (UCH), each of which contains a bipolar signal module driver and a subtracter.

In the prototype device, due to the inertia of the peak detector in the resulting PM signal, at the moments of unrecorded maxima or minima of the initial signal, differences and kinks occur, which causes the broadband of the tail of the spectrum of the divided signal. Such a signal is known to have the slowest convergence of the sum of continuous signals, which is why in order to maintain the high quality of the resulting signal, it is necessary to transmit a relatively large number of signal parameters obtained in each conversion channel, therefore, a low degree of frequency compression of the transmitted audio signals is obtained.

An object of the invention is to increase the degree of frequency compression of audio signals.

This is achieved by a frequency companding device for audio signals, which on the transmitting side contains a series-connected input low-pass filter, an amplitude high-frequency corrector. first DF, first channel low-pass filter. a channel compression unit, the first input of which is connected to the output of the first channel LPF and PF, the first amplifier, the second RF and second channel LPF, the output of which is connected to the second input of the channel compression unit, are connected in series. Each DF contains a series-connected extremator, a voltage comparator, first and second counting triggers, a series-connected first inverter and a first adder, the other input of which is connected to the input of the second adder, the other input of which is connected to the output of the second inverter, and also the third inverter the control input of which is connected to the output of the second trigger, the output of the first trigger is connected to the control input of the second inverter, the second outputs of the first

and the second inverters are connected to the second inputs of the first and second triggers, respectively, through the corresponding first and second pulse shapers. The input of the extremator is the input of the PM, the output of which is the output of the third inverter. Each inverter contains a counting trigger, the input of which is the control input of the inverter, the output of which is the output of the subtractor, the inputs of which are connected via analog switches to the input of the inverter, the second output of which is the combined control input of the first analog key and the trigger output, the inverse output which is connected to the control input of the second analog key.

On the receiving side, the device comprises a channel separation unit, the first output of which is connected to the first phase corrector and the adder connected in series, the other input of which is connected to the output of the first attenuator, the amplitude-corrected low-frequency corrector and the output low-pass filter in series. The second output of the channel separation unit is connected to the input of the first UCH, consisting of the first and second UDCs connected in series, the input of the first of which is the UCH input, and each UDC contains a subtractor connected to the input.

This device is different in that the first delay unit and the first subtractor connected in series between the output of the first DF and the input of the first amplifier are introduced, the first subtractor, the other input of which is connected to the output of the first channel low-pass filter, the third DF, the second delay unit, and the second subtractor connected in series, a second amplifier, a fourth DF and a third channel low-pass filter, the output of which is connected to the fourth input of the channel compression unit, a fourth channel low-pass filter, connected between the output of the third DF and the third input of the seal channel, and a third amplifier series connected, fifth PM and fifth channel lowpass filter connected between the fifth input of the seal channels and an auxiliary output of the third TM, which input is connected to an additional output of the first PM. The output of the fourth channel low-pass filter is connected to the second input of the second subtractor. A third short pulse former, a first sampling and storage unit, a first low-pass filter and a subtractor, the first input of which is an additional output of the high frequency drive, are introduced in series with each DF. and the second input is combined with

the second input of the sampling and storage unit and the input of the extremator, the fourth short pulse former, the second sampling unit and

storage, a second low-pass filter, the output of which is connected to the control input of the inputted first, second and third controlled root extractors, combined with the second input of the first adder. The output of the first controlled root extractor is connected to the input of the first inverter, the control input of which is combined with the input of the third pulse shaper and connected to the second output of the comparator,

5, the first output of which is connected to the input of the fourth pulse former, the second input of the first root extractor is combined with another input of the second sampling and storage unit and connected to the output of the input subtractor, and the second and third controlled root extractors are connected between the output and input of the first adder and the second inverter, respectively and a second adder and a third inverter.

5 At the receiving side, a first subtractor is inserted, connected between the primary and secondary outputs of the first UCh and the input of the first attenuator; serially connected second RF and output

0 adder included between output per-. the first adder and the input of the amplitude bass corrector; connected in series to the second phase corrector, the second adder and the third frequency converter included between the third

5 by the output of the channel separation unit and the second input of the output adder, connected in series with the fourth RF amplifier, the second subtractor and the second attenuator connected between the fourth output of the channel separation unit and the second input of the second adder, and the third phase corrector, the fifth RF and the third, connected in series an attenuator connected between the fifth output of the channel separation unit 5 and the third input of the output adder. The additional output of the fourth RF is connected to the second input of the second subtractor. In each UCH introduced in series connected control unit

0 squaring and a tracking amplitude detector, the output of which is connected to the control input of the squaring unit, the input of which is connected to the output of the second UDF, the input and output of the following detector 5 are the main and additional outputs of the UCh, respectively. A controlled squaring unit, included at the input of the UDF, and a tracking amplitude detector, the input and output of which is connected to the inputs of the subtractor, are introduced into each UDM

with the output and control input of the squaring unit.

These differences are significant because, in the proposed device, the functions of maxima and minima are distinguished with a certain accuracy, which ensure fixation of all maxima or minima of the original signal. As a result, jumps in the output signal of all PMs are eliminated, and due to the non-linear smoothing of this signal with the help of root extractors, the kinks are also eliminated. Consequently, in this device all the AFs as frequency compressors are used more efficiently, therefore, although all the allocated functions of the maxima or minima are also subjected to frequency depression, it is sufficient to use only 1-2 conversion channels in each compressor. Since for most audio transmission systems only 3-4 components can be distinguished for conversion, it is sufficient to use 3-8 narrow-band signal parameters for their transmission;

: As a controlled squaring unit, it is better to use the K525PSZ chip, which works according to the algorithm

Suffer KUex / Uynp (1)

The controlled root extractor contains, for example, a series-connected operational amplifier (OA), a diode and a root extractor, the output of which is the output of a controlled root extractor, between the input of which is connected to the inverting input of the OS and its output, a controlled squaring block, a control input which is the control input of the controlled root extractor, which operates according to the algorithm

ih - KiTjJx Uynp - (2)

It is sufficient to use the K1100SC2 chip as a sampling and storage unit.

All entered low-pass filters contain, for example, two series-connected active integrators and a resistive voltage divider, the input of which is connected to the output of the second integrator, which is the output of the low-pass filter, and the common point of the resistive divider is connected to the non-inverting input of the amplifier of the first integrator, whose inverting input is connected to low pass filter input.

The delay unit contains a series-connected controlled light source, the input of which is the input of the unit

delays, a photoresistor, a load resistor, an amplitude-frequency corrector, and a controlled amplifier, the control input of which is connected to a load resistor, and its 5th output is the output of a delay unit. The following amplitude detector contains an extremator connected in series, a voltage comparator, a short pulse shaper, a block

10 is a sample and storage and low-pass filter, the output of which is the output of the next amplitude detector, the input of which is the combined inputs of the sample and storage unit and the extremator;

15 In FIG. 1 shows a structural electrical circuit transmitting; in FIG. 2 - receiving parts of the proposed device; in FIG. 3 is a schematic diagram of a controlled root extractor; in FIG. 4 - entered low-pass filters; on the

0 FIG. 5 - delay unit; in FIG. 6 is a graph for depicting the operation of the proposed device.

The device contains an input low-pass filter 1, an amplitude high-frequency corrector 2, a block for sampling and storage, an extremator 4, a voltage comparator 6, a short-pulse shaper 6, input low-pass filters 7, a subtractor 8, a controlled root extractor 9, 10, an inverter 11, and a counting trigger 12, analog key 13, adder 14, counting trigger 15, channel low-pass filter 16. delay unit 17, amplifier 18, channel compression unit 19, PF 20, channel separation unit 21, controlled squaring unit 22, next amplitude detector 23, UDF 24, UCh 25, phase corrector 27, amplitude LF 28, output oh low-pass filter 29, OU 30; root extractor 31, integrator 32, resistive voltage divider 33, controlled

0 light source 34, photoresistor 35. load resistor 36, amplitude-frequency corrector 37, controlled amplifier 38, input 39 and additional output 40 of the first DF 10, input 41 of the first root extractor 9,

5 input 42 and output 43 of the first inverter 11, input 44 of the second root extractor 9. input 45 and output 46 of the second inverter 11, additional output 47 of the third PM 10, output 48 of the squaring unit 22, output 49

0 of the first UDC 24, the inputs 50.51 and 52 of the output adder 14.

The audio frequency compander on the transmitting side of FIG. 1 contains sequentially

5 connected by the input low-pass filter 1, the input of which is the input of the transmitting part, the amplitude high-frequency corrector 2, the first low-pass filter 10, the first channel low-pass filter 16, the channel compression unit 19, the input of which is connected to the output of the first low-pass filter 16. and the PF 20, the output of which is the output of the transmitting portion. To the input (I block 19 is connected in series to the first amplifier 18, the second DF 10 and the second channel low-pass filter 16. Each DF 10 contains in series 5 connected extemator 4, a comparator 5, the first and second triggers 15. in series connected the first inverter 11 and the first adder 14 the other input of which is combined with the input of the second adder 14. 10 the other input of which is connected to the output 46 of the second inverter 11, as well as the third inverter 11. the control input of which is connected to the output of the second trigger 15. the output of the first trigger 15 is connected to the control input 15 of the second inverter 11. The second output of the first and second inverters 11 through the corresponding first and second pulse shapers 6 are connected to the second inputs of the corresponding first and 20 second triggers 15. The input of the extremator 4 is the input 39 of the first, DC 10. output which is the output of the third inverter 11. Each inverter 11 contains a trigger 12, the input of which is the 25 control input of the inverter 11, the output 43 of the first of which is the output of the subtractor 8, the inputs of which are connected via analog switches 13 to the stroke 22 of this inverter, the second output of which 30 is the combined control input of the first key 13 and the output of the trigger 12, the inverse output of which is connected to the control input of the second key 13.

On the receiving side of FIG. 2, this device 35 comprises a channel separation unit 21, the input of which is the input of the receiving part, the output of which 1 is connected to the first phase corrector 27 and the adder 14 connected in series, the other 40 input of which is connected to the output of the first attenuator 26, the amplitude bass connected in series a corrector 28 and an output low-pass filter 29, the output of which is the output of the receiving part. The output AND of the channel separation unit 21 45 is connected to the input of the first RF 25, consisting of the first and second UDM 24 connected in series, the input of the first of which is the input of the RF 25, and each of the UDM 24 contains 50 subtractor 8. the output of which is you move 49 of the first UDC 24,

On the transmitting side (Fig. 1), there are introduced, connected between the output of the first DF 1Q and the input of the first amplifier 18, the subsequently connected delay unit 17 and the first subtractor 8, the other input of which is connected to the output of the first channel LPF 16, connected in series to the third DF 10, second delay unit 17.

the second subtractor 8, the second amplifier 18. the fourth DF 10 and the third channel low-pass filter 16, the output of which is connected to the input IV of the channel sealing unit 19; the fourth channel low-pass filter 16, connected between the output of the third DF 10 and the input of III block 19, and the third amplifier 18, the fifth DF 10 and the fifth channel low-pass filter 16, connected between the input V of block 19 and the additional output 47 of the third DF 10 in series, input which is connected to the additional output 40 of the first DF 10. The output of the fourth channel low-pass filter 16 is connected to the second input of the second subtractor 8. A third short-circuit former 6. Short pulses, the first sampling and storage unit 3, the first low-pass filter 7 and the subtractor are introduced in series 8, the first input of which is an additional output 40 of the first DF 10, and the second input is combined with the second input of the sampling and storage unit 3 and the input of the extremator 4; the fourth short pulse shaper 6, the second sampling and storage unit 3, and the second low-pass filter, connected in series

7. the output of which is connected to the control inputs of the introduced first, second and third controlled root extractors 9, combined with the second input of the first adder 14. The output of the first root extractor 9 is connected to the input 42 of the first inverter 11, the control input of which is combined with the input of the third driver 6 pulses and connected to the second output of the comparator 5, the first output of which is connected to the input of the fourth driver 6 pulses, the second input 41 of the first root extractor 9 is combined with another input of the second block 3 of the sample and storage and connected to the output of the subtractor

8. The second and third root switches 9 are connected between the output 44 and the input 45 of the first subtractor 14 and the second inverter 11 and between the output of the second subtract 14 and the input of the third inverter 11.

On the receiving side (Fig. 2), a first subtractor 8 is introduced, connected between the primary and secondary outputs of the first RF 25 and the input of the first attenuator 26; serially connected to the second RF 25 and the output adder 14, connected between the output of the first adder 14 and the input of the amplitude LF corrector 28, serially connected to the second phase corrector 27, the second adder 14 and the third RF 25, wedged between the output Ш of the channel separation unit 21 and the input 51 output adder 14; connected in series the fourth RF 25, the second subtractor

8 and the second attenuator 26, connected between the output of the IV block 21 and the second input of the second adder 14, and the series-connected third phase corrector 27, the fifth RF 25 and the third attenuator 26, connected between the output V of the block 21 and the input 52 of the output adder 14 The additional output of the fourth RF 25 is connected to the second input of the second subtractor 8. In each RF 25, a squaring block 22 and a following amplitude detector 23 are inserted in series, the output of which is connected to the control input of the block 22, the input of which is connected to the output at UDC 24, and the inputs of the detector 23 are respectively the primary and secondary output of the RF 25. In each UDC 24, a squaring block 22 is included, included at the input of the UDC 24 and the following amplitude detector 23, the input and output of which is connected to the inputs of the subtractor 8 and with the output and control input of block 22.

The audio frequency companion device operates as follows.

An initial sound signal of a certain level is fed to the input of the low-pass filter 1, the cutoff frequency of which is determined by the spectrum of the frequency components to be converted. The resulting signal of this filter is input to the amplitude RF corrector 2, in which the alignment of the low- and high-frequency components of this signal occurs. The corrected signal is fed to input 39 of the first PM 10.

An oscillogram quite common with the point of view of subsequent transformations of the signal acting at input 39 is shown in FIG. 6a. The dotted line in this graph shows the function of the minima of this signal.

The sound signal as a composite process can be represented, as is known, in the form

S (t) i) AK (t) t + pk (t). (3) k -l.

(Ok 0) k - 1 This signal is fed to the input of extremator 4, sampling and storage unit 3, and subtractor 8.

The extremator 4 extracts the moments of the maxima and minima of the signal (3) of FIG. ba in the form of voltage drops. Reliable extraction of extrema of even small RF components of the signal (3) is facilitated by the ЈH corrector 2. The resulting signal of the extremator 4 is input

 a comparator 5, which matches the signal levels of the extremator 4 and the control system of the PM 10. From one of the outputs of the comparator 5, the control signal is supplied to the counting input of the trigger 12 of the first inverter 11 to the input of the third driver of short pulses, and from the other to the counting input of the first trigger 15 and the input of the fourth driver 6 short pulses. The pulses generated in the third and fourth blocks 6 are input to the first and second blocks 3 of sampling and storage, respectively, while the duration of these pulses in blocks 3, the values of the maximums or minimums of the input signal for them are sampled, and in the interval between pulses, these blocks are stored that value. The first block 3 samples the minimums of the signal (3) of FIG. ba, as a result of which at the output 40 of the first low-pass filter 7, the function of the minima

s

Sml (t) 2, AK (t) COS U t (t) -A4 (t), (4) k 1

shown separately in FIG. 6h. This signal is fed to another input of subtractor 8, at the output of which 41 the first component of the initial audio signal is allocated

$ 4 (t) S (t) - Sml (t) A «(t) {1 + COS OTs t +

+ P4 (t)} (5)

This signal of FIG. 66 is a signal fixed by all its minima over the time axis. The dotted line in the waveform of FIG. 66 shows the function of the maxima A4 (t) - the envelope of this signal, which is fed to the signal input of the first root extractor 9 and to the other input of the second sampling and storage unit 3. Since the fourth short-pulse driver 6 is excited by an inverted signal with respect to the excitation signal of the third driver 6, it is precisely the maximum function As (t) of signal (5) of FIG. 66, which receives a non-control input, of all root extractors 9 and to another input of all adders 14.

If the 9-root extractors were uncontrollable, then at a low level the signal would be located in the initial - almost linear region of the current-voltage characteristic and practically no root extraction would occur. With a large sound level, the signal would go far beyond the saturation region as a main part and a nonlinear transformation far from root recovery would result. In the controlled root extractor, an automatic

scaling in which, regardless of the change in sound level A4 (t), the root extraction of the rapidly varying function V / 5 (t) 1 + cos ohm t + ((t) of signal (5) is obtained. According to formulas (2) and (5) with Uynp (t ) we have

D24 (t) ± KA4 (t) Vi + cos М t + y, (t) (6). It can be seen from this expression that the function A4 (t) does not undergo non-linear transformation. This feature of the operation of the controlled root extractor on the oscillogram of FIG. 6c is shown as a dashed line of the same function of maxima as the signal of FIG. 66.

The signal (6) of FIG. 6c is fed to input 42 of the first inverter 11, i.e. to the signal input of analog keys 13, to the control input of each of which a control signal is received from one of the outputs of trigger 12. As a result, only even signal pulses (6) of FIG. 6c, and at the output of the other, only odd pulses. These signals at the output .43 of the subtractor 8 form a frequency-divided by two signal of FIG. 6g From formula (6) we have

) K2A4 (t) cos t + -Јф (7)

On the waveform of the signal of FIG. 6d, the dotted line shows the equal functions of the maxima and minima, which are equal to the envelope A4 (t) of the signal (T). This feature of the DF operation makes it possible to use the same function A4 (t) both for controlling all root extractors 9 and for fixing the level of the frequency-divided signal, similar to signal (7) of FIG. 6g with the help of adders 14 included in the DC 10.

As a result of the compensation of the negative function of the minima in (7) by the positive function A4 (t), at the output 44 of the first adder 14, the signal of FIG. 6e, which enters the input 44 of the root extractor 9, the output of which 45 receives the signal of FIG. 6th. This signal is fed to the input 45 of the second inverter 11. At the output 46 of this inverter, the signal of FIG. 6g

D44 (t) K4A4 (t)

divided by an instantaneous frequency of four. Similarly, the frequency is divided in the next DF into two, containing a second adder 14, a third root extractor 9 and a third inverter 11, at the output of which a signal is received

D84 (t) K8A4 (t) COS t + (8)

divided by eight.

The reduction in the spectrum of the signal (8) is obtained mainly by reducing the deviation of the instantaneous frequency of the signal (5), which is significant.

The resulting signal (8) of the first DF 10 is fed to the input of the first channel

Low-pass filter 16c linear phase response and the input of the first block 17 delay. At the output of this filter from the signal (8), the first narrow-band signal is selected - the parameter of the initial sound signal - the first component

future compressed signal. The first parameter signal is input to channel I of channel compaction unit 19. The output signal of block 17 and the low-pass filter 16, having the same delay, at the output of the first subtractor 8 causes a relatively small relatively narrow-band first signal, the remainder, which can be neglected for some audio transmission systems. In systems with an increased requirement for the quality of the reconstructed sound, this residual signal must be stored and subjected to similar transformations in the additional channel. The first residual signal is fed to

the input of the first amplifier 18 of the second channel, the conversion of which is similar to those considered. As a result, the output of the second channel low-pass filter 1 & a second. narrowband parameter signal is supplied to the input AND of the channel multiplexing unit 19.

The function (4) of the minima of FIG. 6h goes to the input of the third DC 10. In

as a result of transformations similar to those considered, a signal is received at the input of the fourth low-pass filter 16

OaaYu - KaAz (g) cos t + - & | ll

and at the inputs And and IV of block 19, two more narrow-band parameter signals are obtained.

On the waveform of the signal of FIG. 6h shows the function of the minima, which is shown separately in FIG. 6i. This signal 2

Sm2 (t) - X g + Wl - AZ () (9)

k 1

is allocated at the auxiliary output 47 of the third DF 10. It is fed to the input of the third amplifier 18 included in the fifth conversion channel. A signal is received at the input of the fifth channel low-pass filter 16

D82 (t) K8A2 (t)

and at its output, a fifth narrowband parameter signal is received, which is input to the V input of block 19.

The possibility of using one and the last signal conversion channel V (9) of FIG. it is visible from its waveform: this signal is rather narrow-band.

All the signal-parameters thus obtained in the compressor in the channel compaction unit 19 form a single compressed signal with a much narrower frequency band compared to the band of the original sound signal. The compressed signal through PF 20 is transmitted in a much more narrowband. than typical communication channels.

At the receiving node, the received signal in the channel separation unit 21 is divided into the same signal parameters as were obtained in the compressor. Transformations in the receiving unit - expander are strictly the reverse of transformations in the compressor. With the output II of block 21, a second parameter signal similar to the signal (8) of FIG. 6g, it is fed to the signal input of the controlled squaring unit 22 of the first UDF 24 included in the first UCH 25. At the output 48, a signal similar to the signal of FIG. 6e, which is fed to the input of the subtractor 8 and the next amplitude detector 23, the output of which is the envelope of the signal (8), which acts on the control input of the block 22 and on the other input of the subtractor 8, According to formulas (1) and (8) , at Uynp A4 (t) a signal is received

Y48 (t) K4A (t) t + illl-jOO)

It can be seen from this formula that, in block 22 too, the function A-q (t) also does not undergo non-linear transformation. From (10) we have

Y48 (t) K2A4 (t) + K2A4 (t) cos t +)

The first term is removed from this signal in the subtractor 8 and a signal is obtained at the output 49

Y44 (t) K2A4 (t)

similar to the signal of FIG. bg with a doubled frequency compared with the signal frequency (8) of FIG. 6g.

The second UDF 24 included in the first RF 25 works similarly. In the last block 22 of the first UCH 25, a unipolar signal is obtained, similar to the signal of FIG. 66, and at the output of the first subtractor 8, a unipolar signal is obtained, the first residual signal is sufficiently accurately reconstructed, which, through the first attenuator 26, compensating the amplification of amplifier 18, is fed to the input of the first adder 14. The received first signal-parameter from output I block 21 receives the input of the first phase corrector 27, which compensates for the delay in the signal in channel II, introduced mainly by the second channel low-pass filter 16, therefore, both signals are in-phase at the inputs of the first adder 14. The resulting signal of this adder is obtained close enough to the signal of FIG. 6g, which is fed to the input of the second RF 25, the transformations of which are similar to those considered. As a result, at the input 50 of the output adder 14, a sufficiently accurately reconstructed unipolar signal of FIG. 66 - the first restored component of the original

sound signal of FIG. 6a.

Similarly, the second component is restored in channels III and IV, and the third component in channel V, which goes to the inputs 51 and 52 of the output

an adder 14, at the output of which a sufficiently accurately reconstructed original signal of FIG. 6a. The output amplitude low-frequency corrector 28 restores the ratio of the levels of the low-frequency and high-frequency components of it, and the output low-pass filter 29 removes possible high-frequency products of nonlinear transforms from it.

The proposed device has significantly wider potential use in comparison with half-coders and in comparison with the Wobank system.

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