CN102098608A - Parametric acoustic array audio playback system and modulation method thereof - Google Patents
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Abstract
The invention provides a parametric acoustic array audio playback system, which comprises a quick modulator, a digital power amplifier and ultrasonic transducer array, wherein the quick modulator is used for receiving an audio analogue signal and converting the audio analogue signal into a high-frequency pulse signal; the digital power amplifier is used for receiving the high-frequency pulse signal and converting the high-frequency pulse signal into an ultrasonic signal; the ultrasonic transducer array is used for receiving the ultrasonic signal and converting the ultrasonic signal into ultrasonic waves; and the quick modulator comprises a receiving device for receiving the audio analogue signal, an analogue-to-digital conversion device for converting the audio analogue signal into an audio digital signal, a signal processing device for modulating the audio digital signal into the high-frequency pulse signal and an output device for outputting frequency modulation pulses. The invention also provides a parametric acoustic array audio playback system-based modulation method. By the parametric acoustic array audio playback system and the modulation method of the system, modulation speed is increased, accuracy is higher, and user requirements can be better met.
Description
[technical field]
The present invention relates to a kind of parametric array audio playback systems and modulator approach thereof, relate in particular to a kind of parametric acoustic array audio playback systems and modulator approach thereof.
[background technology]
Along with the progress of science and technology, the field of digital signals of sound is more and more general, and the parametric acoustic array audio playback systems becomes the popular research topic that people inquire into.The parametric acoustic array audio playback systems of correlation technique is to obtain impulse waveform by reference signal and comparator acting in conjunction.Yet because signal will compare in chronological order one by one, it is to be compared that this makes that a large amount of signals needs etc., thereby cause the inefficiency of parametric acoustic array audio playback systems.And the pulse precision that the parametric acoustic array audio playback systems of correlation technique obtains also is subjected to audio sample rate and calculates quantitative limitation.
Therefore, being necessary to propose a kind of new parametric acoustic array audio playback systems overcomes the problems referred to above in fact.
[summary of the invention]
The technical problem that the present invention need solve provides parametric acoustic array audio playback systems and the modulator approach thereof that a kind of modulating speed is faster, precision is higher.
According to above-mentioned technical problem, designed a kind of parametric acoustic array audio playback systems, its objective is such realization: a kind of parametric acoustic array audio playback systems, wherein, described parametric acoustic array audio playback systems comprises and is used to the fast modulation device that receives audio analog signals and convert thereof into high-frequency pulse signal, receives described high-frequency pulse signal and converts thereof into the digital power amplifier of ultrasonic signal and receive described ultrasonic signal and convert thereof into hyperacoustic ultrasonic transducer battle array.Described fast modulation device comprises the receiving system that is used to receive audio analog signals, described audio analog signals is converted to the analog-digital commutator of audio digital signals, described audio digital signals is modulated into the signal processing apparatus of high-frequency pulse signal and with the output device of described high-frequency pulse signal output.
Preferably, described signal processing device is changed to the application-specific integrated circuit (ASIC) of digital signal processor or field programmable gate array or high-frequency signal conversion.
Preferably, described signal processing apparatus has used pulse-width modulation method to handle described audio digital signals.
The present invention also provides a kind of modulator approach based on parametric acoustic array audio playback systems of the present invention, and wherein, this modulator approach comprises the steps:
(1) provide a fast modulation device, it comprises: receiving system, analog-digital commutator, signal processing apparatus and output device;
One digital power amplifier is provided;
One ultrasonic transducer battle array is provided;
One carrier wave is provided;
(2) A, be transferred to described analog-digital commutator after gathering audio analog signals and it is loaded into described carrier wave by described receiving system;
B, frequency that described analog-digital commutator setting is identical with described carrier wave are as sample frequency, described audio analog signals obtains audio digital signals through the sampling and the processing of described analog-digital commutator, and described analog-digital commutator is transferred to described signal processing apparatus with described audio digital signals;
The described audio digital signals that C, described signal processing apparatus will receive obtains high-frequency pulse signal p (t) by the processing of pulse-width modulation method, the cycle of described high-frequency pulse signal is predetermined, its pulse duration and pulse spacing are to calculate according to described audio digital signals, calculate the positive pulse p (t) of described high-frequency pulse signal earlier
+:
According to the symmetry of signal, the wave function p (t)-then of negative pulse need not to calculate again, by positive pulse p (t)+anti-phase and postpone 1/2 cycle and obtain, thereby obtains high-frequency pulse signal p (t):
And described high-frequency pulse signal exported to described digital power amplifier by described output device;
D, described high-frequency pulse signal obtain ultrasonic signal and drive described ultrasonic transducer battle array task driven signal after the processing and amplifying of described digital power amplifier, described ultrasonic signal obtains ultrasonic wave through the processing of described ultrasonic transducer battle array.
Preferably, this modulator approach also is provided with the modification method to the frequency spectrum intermodulation distortion of described audio digital signals, promptly described audio digital signals is done preliminary treatment, described preliminary treatment comprises that the index of modulation of adjusting described audio digital signals and the direct current that increases described audio digital signals are worth partially, thereby obtain modulation signal, the bandwidth of described modulation signal is expanded expansion modulation signal after obtaining handling.
Preferably, this modulator approach also is provided with the modification method to the frequency spectrum intermodulation distortion of described audio digital signals, promptly described audio digital signals being done phase shifts handles, thereby obtain first audio digital signals and second audio digital signals, making described first audio digital signals and second audio digital signals do pulse width modulation by described signal processing apparatus respectively again handles, and then obtain first high-frequency pulse signal and second high-frequency pulse signal, with described first high-frequency pulse signal and the second high-frequency pulse signal addition or subtract each other, obtain revised high-frequency pulse signal.
Compare with correlation technique, the modulating speed of parametric acoustic array audio playback systems of the present invention and modulator approach thereof is faster, and precision is higher, more can satisfy user demand.
[description of drawings]
Fig. 1 is the schematic flow sheet of parametric array audio playback systems one embodiment of the present invention.
Fig. 2 is the timing chart that obtains after parametric array audio playback systems of the present invention is modulated audio signal.
[embodiment]
The invention will be further described below in conjunction with drawings and embodiments.
As shown in Figure 1, a kind of parametric acoustic array audio playback systems 10, wherein, parametric acoustic array audio playback systems 10 comprises and is used to the fast modulation device 1 that receives audio analog signals and convert thereof into high-frequency pulse signal, receives high-frequency pulse signal and also converts thereof into the digital power amplifier 6 of ultrasonic signal and receive ultrasonic signal and convert thereof into hyperacoustic ultrasonic transducer battle array 7.The fast modulation device comprises the receiving system 2 that is used to receive audio analog signals, audio analog signals is converted to the analog-digital commutator 3 of audio digital signals s (t), audio digital signals s (t) is modulated into the signal processing apparatus 4 of high-frequency pulse signal and with the output device 5 of described high-frequency pulse signal output.
In the process of signal transmission, be not that signal is directly transmitted, but the ripple of a signal and a fixed frequency interacted that this process is called loading.The ripple of described fixed frequency is called carrier wave.Concrete, in the present embodiment, parametric acoustic array audio playback systems 10 is provided with a carrier frequency fc=48KHz, it is ADSP 21364EZKIT Digital Signal Processing evaluation board that fast modulation device 1 is selected model for use, it can conveniently use digital signal processor (the Digital Signal Processor of other model, be called for short DSP), around it, increase other auxiliary equipment, thereby form the synthetic circuit that can finish certain task.Because it is signal processing apparatus 4 that this device is provided with the floating type digital signal processor, its computing is accurately convenient, and it has comprised stereo RCA interface is that receiving system 1, AD1835 audio frequency analog to digital converter are that analog-digital commutator 3, DAI digital audio interface are output device 5, also bear the audio frequency input function and the AD1835 audio frequency analog to digital converter of the fast modulation device 1 among the present invention is an analog-digital commutator 3, the DAI digital audio interface is that output device 5 is also born pulse input interface function.Certainly, signal processing apparatus 4 is not limited only to this, also can be field programmable gate array (Field-Programmable Gate Array is called for short FPGA) or application-specific integrated circuit (ASIC) (ApplicationSpecific Integrated Circuit, be called for short ASIC) etc., but its principle is the same.
The present invention also provides a kind of modulator approach based on parametric acoustic array audio playback systems 10 of the present invention, and wherein, this modulator approach comprises the steps:
(1) provide one to be used to the fast modulation device 1 that receives audio analog signals and convert thereof into high-frequency pulse signal, specifically be that model is an ADSP 21364EZKIT Digital Signal Processing evaluation board, comprise: the stereo RCA interface that is used to gather audio analog signals is a receiving system 2, the AD1835 audio frequency analog to digital converter that described audio analog signals is converted to audio digital signals s (t) is an analog-digital commutator 3, described audio digital signals s (t) is modulated into the signal processing apparatus 4 of high-frequency pulse signal and is output device 5 the DAI digital audio interface of described high-frequency pulse signal output
One digital power amplifier 6 is provided;
One ultrasonic transducer battle array 7 is provided;
One carrier wave is provided;
(2) A, be transferred to described analog-digital commutator after gathering audio analog signals and it is loaded into described carrier wave by receiving system 2.With the MP3 player is that audio-source produces audio analog signals, and other loud speaker etc. is all feasible certainly, is that receiving system 2 is gathered audio analog signals and it is transferred to analog-digital commutator 3 by stereo RCA interface.
B, analog-digital commutator 3 is provided with the frequency identical with carrier wave as sample frequency, carrier frequency is made as fc=48KHz in the present embodiment.Audio analog signals is that AD1835 audio frequency analog to digital converter is handled through analog-digital commutator 3, and sampling with the sample frequency of 48KHz obtains audio digital signals s (t) and this audio digital signals s (t) is transferred to signal processing apparatus 4.Certainly, AD1835 audio frequency analog to digital converter is that the sample frequency of analog-digital commutator 3 can also be made as 96KHz and 192KHz etc.The sample frequency that analog-digital commutator 3 is set in the present embodiment is the same with carrier frequency, other processing that this just makes that it goes without doing when audio digital signals s (t) and carrier wave loaded, thus the processing speed of parametric acoustic array audio playback systems of the present invention can be accelerated.Certainly, carrier frequency also can be made as other value, but its principle is the same.
The described audio digital signals s (t) that C, signal processing apparatus 4 will receive calculates its pulse duration and pulse spacing by pulse-width modulation method, utilize pulse width modulation to realize the amplitude modulation(PAM) of pulse according to the momentum area equivalent principle of burst pulse again, thereby obtain the high-frequency pulse signal of corresponding amplitude, and described high-frequency pulse signal is exported to described digital power amplifier 6 by described output device 5.
D, high-frequency pulse signal obtain ultrasonic signal and drive the drive signal of ultrasonic transducer battle array 7 work after the processing and amplifying of described digital power amplifier 6 gets, ultrasonic signal just obtains ultrasonic wave through the processing of ultrasonic transducer battle array 7, and ultrasonic wave is demodulated to sound for hearing certainly through air.
Modulator approach is selected the wide modulation of the simple venation in the pulse-width modulation for use, promptly audio digital signals s (t) is done the high-frequency pulse signal that the single pulse width modulation obtains.The cycle of high-frequency pulse signal is predetermined, and its pulse duration and pulse spacing are that the size according to audio digital signals s (t) calculates.Concrete, the audio digital signals s (t) that makes described signal processing apparatus 4 receive satisfies-1≤s (t)≤1, and t is arbitrary moment.In order to prevent ovennodulation, need digital audio and video signals s (t) is added direct current biasing d, thereby obtain modulation signal g (t), make modulation signal g (t) all the time greater than 0.
g(t)＝d+m·s(t)，m≤d (1)
Wherein, d is that direct current is worth partially, and m is the index of modulation.
G (t) is a modulation signal, obtains after doing particular procedure by audio digital signals s (t), as the index of modulation of adjusting audio digital signals and the direct current that increases audio digital signals value etc. partially.
In the present embodiment, because 0＜g (t)＜1 in order to make full use of the dynamic range of g (t), at first increases direct current biasing d, its value is made as g (t)/2, and promptly 0.5; Superposed signal s (t) on direct current biasing d again.Because-1≤s (t)≤1, its dynamic range is excessive, need multiply by index of modulation m, feasible-1≤d+ms (t)≤1, and (d 1-d), so can obtain m＜0.5 when d=0.5, establishes m=0.4 to m＜min in the present embodiment.Certainly, direct current biasing d and index of modulation m also can be made as other value, all are feasible as long as meet the demands, but its principle is the same.By obtaining behind formula (1) the substitution occurrence:
g(t)＝0.5+0.4·s(t)
The expression formula of ultrasonic signal c (t) behind the amplitude modulation(PAM) that expectation obtains is:
c(t)＝g(t)·sin(2π·f
c·t)
Wherein, f
cBe the frequency of ultrasonic signal, t is arbitrary time.
As shown in Figure 2, the ultrasonic signal c (t) after modulation is that a frequency is f
c=48KHz, the sinusoidal signal that amplitude changes.For each cycle of ultrasonic signal c (t), amplitude is that first positive cycle is g (t)/2 with a duty ratio, goes match on the occasion of the positive pulse that symmetry axis was located in 1/4 cycle; Amplitude is g (t)/2 for second negative cycle with a duty ratio, and the negative value symmetry axis goes match in the negative pulse at 3/4 cycle place.Wherein, the wave function p (t) of positive pulse
+Can calculate by following formula:
Wherein, T
cBe Cycle Length, T
c=1/f
c, n=0,1,2,3 ....
According to the symmetry of signal, the wave function p (t) of negative pulse _ can need not calculates, and is anti-phase and postpone 1/2 cycle and obtain by positive pulse.
According to above-mentioned principle as can be known, described audio digital signals s (t)) after described digital signal processing device modulation, obtains high-frequency pulse signal p (t), resulting high-frequency pulse signal p (t) is three level pulse signals, it also is quasi-periodic signal, its signal amplitude is represented with-1,0,1, then can draw the high-frequency pulse signal p expression formula in (t) arbitrary cycle:
Wherein, t is arbitrary time, T
cBe Cycle Length, T
c=1/f
c, f
c=48KHz, g (t) is a modulation signal, n=0,1,2,3 ....
More excellent, may there be the intermodulation distortion between frequency spectrum in the parametric acoustic array system that pulse-width modulation realizes, and therefore, the modulator approach of parametric acoustic array audio playback systems of the present invention also is provided with the modification method to the intermodulation distortion between frequency spectrum.Concrete, audio digital signals s (t) is done preliminary treatment, described preliminary treatment comprises that the index of modulation of adjusting audio digital signals and the direct current that increases described audio digital signals are worth partially, thereby obtains modulation signal g (t).To the bandwidth of described modulation signal g (t) expand after obtaining handling expansion modulation signal g ' (t).
Method by such spread bandwidth carries out compensating to the intermodulation distortion between the audio digital signals frequency spectrum gradually, and then reduces the distortion spectrum of audio digital signals, improves parametric acoustic array audio playback systems modulation accuracy.
Present embodiment also provides the method for the intermodulation distortion between another kind of correction frequency spectrum, promptly described audio digital signals s (t) is done 90 ° of phase shifts, thereby obtains first audio digital signals and second audio digital signals.Certainly be not limited only to 90 °, but principle is the same.Making described first audio digital signals and second audio digital signals do pulse width modulation by described signal processing apparatus respectively again handles, and then obtain first high-frequency pulse signal and second high-frequency pulse signal, with described first high-frequency pulse signal and the second high-frequency pulse signal addition or subtract each other, obtain revised high-frequency pulse signal, revised high-frequency pulse signal has only the upper sideband or the lower sideband of double-side band, and then has avoided the intermodulation distortion of upper sideband and lower sideband.
Compare with correlation technique, parametric acoustic array audio playback systems of the present invention and using method thereof are according to the fixed-frequency and the signal symmetry of carrier signal in the parametric acoustic array audio playback systems, directly accurately calculate each pulse duration and the interval of pulse width modulated waveform by mathematical relationship, the precision and the formation speed of pulse have greatly been improved, thereby make that the modulating speed of parametric acoustic array audio playback systems of the present invention and modulator approach thereof is faster, precision is higher, more can satisfy user demand.
Above-described only is embodiments of the present invention, should be pointed out that for the person of ordinary skill of the art at this, under the prerequisite that does not break away from the invention design, can also make improvement, but these all belongs to protection scope of the present invention.
Claims (6)
1. parametric acoustic array audio playback systems, it is characterized in that: described parametric acoustic array audio playback systems comprises and is used to the fast modulation device that receives audio analog signals and convert thereof into high-frequency pulse signal, receive described high-frequency pulse signal and convert thereof into the digital power amplifier of ultrasonic signal and receive described ultrasonic signal and convert thereof into hyperacoustic ultrasonic transducer battle array, described fast modulation device comprises the receiving system that is used to receive audio analog signals, described audio analog signals is converted to the analog-digital commutator of audio digital signals, described audio digital signals is modulated into the signal processing apparatus of high-frequency pulse signal and the output device that described high-frequency pulse signal is exported.
2. parametric acoustic array audio playback systems according to claim 1 is characterized in that: described signal processing device is changed to the application-specific integrated circuit (ASIC) of digital signal processor or field programmable gate array or high-frequency signal conversion.
3. parametric acoustic array audio playback systems according to claim 2 is characterized in that: described signal processing apparatus has used pulse-width modulation method to handle described audio digital signals.
4. the modulator approach of a parametric acoustic array audio playback systems, it is characterized in that: this modulator approach comprises the steps:
(1) provide a fast modulation device, it comprises: receiving system, analog-digital commutator, signal processing apparatus and output device;
One digital power amplifier is provided;
One ultrasonic transducer battle array is provided;
One carrier wave is provided;
(2) A, be transferred to described analog-digital commutator after gathering audio analog signals and it is loaded into described carrier wave by described receiving system;
B, frequency that described analog-digital commutator setting is identical with described carrier wave are as sample frequency, described audio analog signals obtains audio digital signals through the sampling and the processing of described analog-digital commutator, and described analog-digital commutator is transferred to described signal processing apparatus with described audio digital signals;
The described audio digital signals that C, described signal processing apparatus will receive obtains high-frequency pulse signal p (t) by the processing of pulse-width modulation method, the cycle of described high-frequency pulse signal p (t) is predetermined, its pulse duration and pulse spacing are to calculate according to described audio digital signals, calculate the positive pulse p (t) of described high-frequency pulse signal earlier
+:
According to the symmetry of signal, the wave function p (t)-then of negative pulse need not to calculate again, by positive pulse p (t)+anti-phase and postpone 1/2 cycle and obtain, thereby obtains high-frequency pulse signal p (t):
And described high-frequency pulse signal exported to described digital power amplifier by described output device;
D, described high-frequency pulse signal obtain ultrasonic signal and drive the drive signal of described ultrasonic transducer battle array work after the processing and amplifying of described digital power amplifier, described ultrasonic signal obtains ultrasonic wave through the processing of described ultrasonic transducer battle array.
5. the modulator approach of parametric acoustic array audio playback systems according to claim 4, it is characterized in that: this modulator approach also is provided with the modification method to the frequency spectrum intermodulation distortion of described audio digital signals, promptly described audio digital signals is done preliminary treatment, described preliminary treatment comprises that the index of modulation of adjusting described audio digital signals and the direct current that increases described audio digital signals are worth partially, thereby obtain modulation signal, the bandwidth of described modulation signal is expanded expansion modulation signal after obtaining handling.
6. the modulator approach of parametric acoustic array audio playback systems according to claim 4, it is characterized in that: this using method also is provided with the modification method to the frequency spectrum intermodulation distortion of described audio digital signals, promptly described audio digital signals being done phase shifts handles, thereby obtain first audio digital signals and second audio digital signals, making described first audio digital signals and second audio digital signals do pulse width modulation by described signal processing apparatus respectively again handles, and then obtain first high-frequency pulse signal and second high-frequency pulse signal, with described first high-frequency pulse signal and the second high-frequency pulse signal addition or subtract each other, obtain revised high-frequency pulse signal.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103873978B (en) * | 2012-12-17 | 2017-06-27 | 联想(北京)有限公司 | The method and electronic equipment of information processing |
| CN110972030A (en) * | 2018-10-01 | 2020-04-07 | 恩智浦有限公司 | Audio processing system |
| CN111818422A (en) * | 2020-07-03 | 2020-10-23 | 电子科技大学 | Fixed-point sound wave transmitting device based on parametric array principle |
| CN115499738A (en) * | 2022-09-21 | 2022-12-20 | 电子科技大学 | Programmable parametric array speaker with safety device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN2792024Y (en) * | 2005-04-01 | 2006-06-28 | 康佳集团股份有限公司 | Audio power amplifier |
| CN101111095A (en) * | 2007-07-12 | 2008-01-23 | 电子科技大学 | Sound frequency directional loudspeaker system based on consumer electronic equipments |
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2010
- 2010-12-13 CN CN201010584960.9A patent/CN102098608B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2792024Y (en) * | 2005-04-01 | 2006-06-28 | 康佳集团股份有限公司 | Audio power amplifier |
| CN101111095A (en) * | 2007-07-12 | 2008-01-23 | 电子科技大学 | Sound frequency directional loudspeaker system based on consumer electronic equipments |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103873978B (en) * | 2012-12-17 | 2017-06-27 | 联想(北京)有限公司 | The method and electronic equipment of information processing |
| CN110972030A (en) * | 2018-10-01 | 2020-04-07 | 恩智浦有限公司 | Audio processing system |
| CN111818422A (en) * | 2020-07-03 | 2020-10-23 | 电子科技大学 | Fixed-point sound wave transmitting device based on parametric array principle |
| CN111818422B (en) * | 2020-07-03 | 2021-10-26 | 电子科技大学 | Fixed-point sound wave transmitting device based on parametric array principle |
| CN115499738A (en) * | 2022-09-21 | 2022-12-20 | 电子科技大学 | Programmable parametric array speaker with safety device |
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