CN1929696A - Method and device for loudspeaker array setting by using quadratic residue sequence phase delay - Google Patents

Abstract

This invention relates to one method by use of second remaining sequence for microphone setting, which adopts phase time lag to realize microphone direction optimization and applies remaining sequence into microphone array. Each microphone unit feeds back different phase time lags signals to get one secondary remaining sequence.

Description

Utilize quadratic residue sequence phase delay that the method and the device of loudspeaker array are set

Technical field

The present invention designs the method to set up of loudspeaker array, promptly improves the directive property of loudspeaker array by method for processing signals, makes it all have directive property preferably when low frequency and high frequency, to improve the uniformity coefficient of radiated sound field.

Background technology

In the 21st century that science and technology is constantly brought forth new ideas, for satisfying the new demand of people to high-quality audiovisual entertainment, the increasing large-scale hall, venue occur like the mushrooms after rain.Because single loud speaker is difficult to the sound pressure level that reaches required and desirable, so, at these large stadiums and some outdoor location (as gymnasium, open deck) thereof, large-scale sound-reproducing system (with the loudspeaker array of a plurality of loud speakers compositions) just becomes inevitable choice.

Compare with traditional sound-reproducing system, large-scale loudspeaker array sound-reproducing system has following advantage:

1. can produce enough sound pressure levels, to satisfy the demand of large stadium and open-air performance;

2. the interference effect between multi-loudspeaker makes directive property be more prone to control, satisfies the needs of actual conditions;

3. in high reverberation environment, but inhibitory reflex sound improves the definition of voice;

4. near-field region and far-field region acoustic pressure unevenness are reduced, make whole audience audience can both obtain good hearing effect.

Above various advantages makes that all large-scale loudspeaker array sound-reproducing system has obtained using widely.

Meanwhile, for satisfying the demand of indoor high-quality audiovisual entertainment, the loudspeaker array of miniaturization also is applied in the audio-visual equipment such as panel TV set (as liquid crystal TV set, plasma TV), home theater gradually, because the advantage of aspects such as its power, shape, outward appearance is more and more favored.

Yet also there are the many defectives that can't avoid in the array of forming with a plurality of loud speakers.This is that its directivity pattern is the function of frequency because the interference between the multi-loudspeaker can produce directive property.When high frequency, the main lobe of this directivity pattern narrows down and can produce secondary lobe, and the position of secondary lobe is very responsive for frequency change, therefore makes that the sound field distributed pole is inhomogeneous, makes the application of loudspeaker array be limited to.The radiation problem of multi-loudspeaker sound-reproducing system is that for many years but the electroacoustic field presses for insoluble problem.

Inhomogeneous in order to overcome the sound field that frequency change causes, people have proposed some solutions:

Klepper David L., Steele Douglas W., " Constant Direction Characteristics froma Line Source Array, " J.A.E.S, Volume 11 Number 3 pp.198-202; July 1963 (direction character of loudspeaker array) uses electricity or acoustic filter, filters the high frequency of part unit.

Menno Van Der Wal, et al, " Design of Logarithmically SpacedConstant-Directivity Transducer Arrays; " J.Audio Eng.Soc., Vol.44, pp.497-507, (1996 June). (design of logarithm space array) arranges loudspeaker array with logarithmic interval.

Keele, Jr., D.B., " Effective Performance of Bessel Arrays ", J.A.E.S., Volume 38 Number10 pp.723-748; October 1990. utilizes the Bessel function property, and for each point source in the array distributes different strengths of sound source, source strength is proportional to particular B essel function, thereby improves the sound field uniformity coefficient.

Jiang Chao, Shen Yong, " An Omni-directivity Sound Source Array, " Mo.P2.11, The 18 ^ThInternational Congress On Acoustics, Kyoto, Japan, April 2004. (omnidirectional sound source array) adjusts source strength according to sinc function rule, has not only improved the uniformity coefficient of sound field, has also improved phase characteristic.

Said method all is by adjusting the uniformity coefficient that source strength improves the loudspeaker array radiated sound field, design deficiencies such as complicated, that radiation efficiency is low but exist, lacking ideal solution.

Shen Yong, Jiang Chao, Xu Xiaobing etc., utilize quadratic residue sequence that the method and the device of loudspeaker array are set, number of patent application 200410044849.5, quadratic residue sequence is used to optimize the directive property of loudspeaker array,, thereby improves the uniformity coefficient of sound field for each loudspeaker unit is provided with different signal lags.

Because signal lag and frequency are closely related, though said method can significantly improve the uniformity coefficient of sound field, directivity pattern changes greatly when frequency change, produces uneven sound field near some frequency.

Example: 7000Hz-8000Hz this very in the small frequency scope, see both directivity pattern situations of change.Coverage is more even when 7000Hz for directivity pattern (Fig. 4 is the sensing figure of the method for time of delay), and there is the broad valley point in place, 15 degree angle when 8000Hz, therefore the audience in this relative broad range can't hear the sound of this frequency, and radiated sound field is inhomogeneous.

Quadratic residue sequence is a kind of mathematical sequence, and this sequence is determined by following formula:

d _n＝n ²?mod?N。

D wherein _nBe n element of sequence, N is a sequence length, gets odd prime usually, and mod represents delivery.Such as when the N=5, this sequence is: 0,1,4,4,1; When N=7, this sequence is: 0,1,4,2,2,4,1; When N=11, this sequence is: 0,1,4,9,5,3,3,5,9,4,1.

For the array of an omnidirectional, need accomplish that when frequency changes within the specific limits it is constant substantially that directivity pattern keeps.Realize the omnidirectional array by phase retardation, the strict theoretical support is arranged, can guarantee above-mentioned requirements.

Summary of the invention

The objective of the invention is: quadratic residue sequence is applied on the loudspeaker array, provides a kind of method for designing simple relatively, the directive property uniformity obtains the obviously improved method that loudspeaker array is set.

The object of the present invention is achieved like this: utilize quadratic residue sequence that the method for loudspeaker array is set, adopt the optimization of the method realization directivity of loudspeaker of phase place time-delay, quadratic residue sequence is applied on the loudspeaker array, and each loudspeaker unit is fed through the signal of out of phase time-delay; The phase place time-delay of each loudspeaker unit of loudspeaker array is proportional to a quadratic residue sequence accordingly.The present invention is meant and introduces phase difference successively on the loudspeaker array of equidistantly arranging in a line, can make directive property even equally.

Concrete scheme is on the array of N for to introduce phase difference on loudspeaker array in length, the signal delay phase place  of n loudspeaker unit _n, phase retardation is proportional to a quadratic residue sequence and represents with following formula:

 _n=(n ²ModN) *  _n,  wherein _n=2 π/N.N is a sequence length, and mod represents delivery.Such as,

When N=5, the phase delay of each loud speaker is respectively:

$0,\frac{2\mathrm{\π}}{7},\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}$

When N=7, the phase delay of each loud speaker is respectively:

$0,\frac{2\mathrm{\π}}{7},\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}\×2,\frac{2\mathrm{\π}}{7}\×2,\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}$

When N=11, the phase delay of each loud speaker is respectively:

$0,\frac{2\mathrm{\π}}{7},\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}\×9,\frac{2\mathrm{\π}}{7}\×5,\frac{2\mathrm{\π}}{7}\×3,\frac{2\mathrm{\π}}{7}\×3,\frac{2\mathrm{\π}}{7}\×5,\frac{2\mathrm{\π}}{7}\×9,\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}$

The directive property of loudspeaker array is improved.

Utilize quadratic residue sequence that the device of loudspeaker array is set, drive the loudspeaker array signal source and pass through by driving loud speaker after the time-delay of above-mentioned requirements phase place delay unit more respectively.Loudspeaker unit is determined by the actual operating frequency scope at interval.

The present invention be used for equidistantly arrange in a line or the loudspeaker array of the camber line of near linear on introduce phase difference.

The contrast of Fig. 2, Fig. 3, and the contrast of Fig. 8, Fig. 9 shows that according to the present invention quadratic residue sequence is applied on the loudspeaker array, the uniformity of directive property is obviously improved; In addition, the contrast of Fig. 4, Fig. 5 shows, compares with the method for utilizing quadratic residue sequence that array element time of delay is set, and the method for phase retardation of the present invention can obviously be improved the inhomogeneities of the sensing figure that frequency change among a small circle brings.Pole figure among Fig. 5 (method of phase retardation) is compared with Fig. 4, keeps almost constant directive property at 7000Hz-8000Hz, not with the frequency significant change.Can cover nearly all angle, the uniformity coefficient of radiated sound field has very big change than the former.

In other frequency ranges, observe, also can obtain similar conclusion.

Characteristics of the present invention are: sensing figure after testing represents, uses the present invention, and the directive property of loudspeaker array is obviously improved, and radiated sound field is more even, and method for designing is simple relatively, and the drive circuit of loudspeaker array is also very simple.Miniaturized loudspeakers array of the present invention also is applied to can satisfy the demand of indoor high-quality audiovisual entertainment in the equipment such as panel TV set (as liquid crystal TV set, plasma TV), home theater.

Description of drawings

Fig. 1 is example according to the present invention with N=7, and this moment, corresponding quadratic residue sequence was 0,1,4,2,2,4,1 loudspeaker array implementation method schematic diagram.

Fig. 2 is when N=7, and the loudspeaker array of optimizing without quadratic residue sequence points to figure, the directive property of array when representing different frequency respectively, (a) 1kHz among Fig. 2; (b) 2kHz among Fig. 2; (c) 4kHz among Fig. 2; (d) 8kHz among Fig. 2.Array element spacing d=0.1m, down together.

Fig. 3 when N=7, utilizes quadratic residue sequence to carry out the loudspeaker array sensing figure that phase delay is optimized, the directive property of array when representing different frequency respectively, (a) 1kHz among Fig. 3 according to the present invention; (b) 2kHz; (c) 4kHz; (d) 8kHz.

Fig. 4 utilizes quadratic residue sequence to carry out the loudspeaker array sensing figure that " time delay " optimized, the directive property of array when representing different frequency respectively, (a) 7kHz among Fig. 4 when N=7; (b) 7.5kHz; (c) 8kHz.

Fig. 5 when N=7, utilizes quadratic residue sequence to carry out the loudspeaker array sensing figure that phase delay is optimized, the directive property of array when representing different frequency respectively, (a) 7kHz among Fig. 5 according to the present invention; (b) 7.5kHz; (c) 8kHz.

Fig. 6 when N=7, major axes orientation (0 degree direction) far field frequency response contrast: dotted line---time of delay method; Solid line---phase retardation method.Abscissa is a frequency, and ordinate is the sound pressure level that dB represents, down together.

Fig. 7 departs from the far field frequency responses contrast of main shaft 45 degree direction: dotted line when N=7---time of delay method; Solid line---phase retardation method.

Fig. 8 optimizes loudspeaker array without quadratic residue sequence and points to figure, the directive property of array when representing different frequency respectively, (a) 1kHz among Fig. 8 when N=5; (b) 2kHz; (c) 8kHz 4kHz:(d).Array element spacing d=0.1m, down together.

Fig. 9 when N=5, utilizes quadratic residue sequence to carry out the loudspeaker array sensing figure that phase delay is optimized, the directive property of array when representing different frequency respectively, (a) 1kHz among Fig. 9 according to the present invention; (b) 2kHz; (c) 4kHz; (d) 8kHz.

Figure 10 when N=5, major axes orientation (0 degree direction) far field frequency response contrast: dotted line---time of delay method; Solid line---phase retardation method.

Figure 11 departs from the far field frequency responses contrast of main shaft 45 degree direction: dotted line when N=5---time of delay method; Solid line---phase retardation method.

Specific implementation method

When N=7, quadratic residue sequence is: 0,1,4,2,2,4,1.Then circuit is: drive the loudspeaker array signal source and pass through respectively $0,\frac{2\mathrm{\π}}{7},\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}\×2,\frac{2\mathrm{\π}}{7}\×2,\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}$ Phase delay cell, through driving loud speaker through power amplification again after the phase delay.Compared with prior art, the delay of phase delay cell obviously is not the proportional relation of simple time delay.Directive property under several frequencies as shown in Figure 3 at this moment.

When N=5, quadratic residue sequence is: 0,1,4,4,1.Then circuit is: drive the loudspeaker array signal source and pass through respectively $0,\frac{2\mathrm{\π}}{7},\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}$ Phase delay cell, through driving loud speaker through power amplification again after the phase delay.Directive property under several frequencies as shown in Figure 9 at this moment.

The far field frequency response:

With N=7 is example, the method for time of delay before the dotted line representative, and solid line is represented the method for phase retardation.Angle θ represents to depart from the degree of main shaft.Far field frequency response when below investigating different angles.

When θ=0 was spent, frequency response as shown in Figure 6.

1/12 octave, dotted line acoustic pressure variances sigma=4.9928e-4

Solid line acoustic pressure variances sigma=3.6082e-9

On main shaft, by the method for phase retardation, it is constant that the frequency response of main shaft keeps, and is a big advantage of this method.

When θ=45 were spent, frequency response as shown in Figure 7.

1/12 octave, dotted line acoustic pressure variances sigma=6.7422e-4

Solid line acoustic pressure variances sigma=5.6070e-5

In the zone of departing from main shaft, the method for phase retardation still keeps the advantage of frequency response aspect, and the little order of magnitude of solid line variance shows that the frequency response fluctuation is little, is better than dotted line.

On other depart from the angle of main shaft, observe, also can obtain above-mentioned conclusion.

And during N=5, array is seen Figure 10, Figure 11 at 0 degree and 45 frequency responses of spending directions, can access similar conclusion.

In sum, the method for phase retardation is compared with the method for time delay, although all be to have used quadratic residue sequence, The form of theory diagram is also to some extent similar, but there is very big difference in they. The method of phase retardation is owing to be tight from theory Lattice are derived, and have the obvious advantage that the directivity pattern variation is little, frequency response is straight.

Claims (4)

1, utilize quadratic residue sequence that the method for loudspeaker array is set, it is characterized in that the method that adopts phase place to delay time realizes the optimization of the directivity of loudspeaker, quadratic residue sequence is applied to loudspeaker array, and each loudspeaker unit is fed through the signal of out of phase time-delay; The phase place time-delay that is each loudspeaker unit of loudspeaker array is proportional to a quadratic residue sequence accordingly.

2, the method for utilizing quadratic residue sequence phase delay that loudspeaker array is set as claimed in claim 1 is characterized in that: equidistantly arrange in a line or the loudspeaker array of the camber line of near linear on introduce phase difference.

3, the method for utilizing quadratic residue sequence phase delay that loudspeaker array is set as claimed in claim 1 is characterized in that: introducing phase difference on loudspeaker array, is on the array of N in length, to the signal delay phase place  of n loudspeaker unit _n, make  _n=(n ²Mod N) *  ₀,  wherein ₀=2 π/N; N is a sequence length, and mod represents delivery.

4, utilize quadratic residue sequence phase delay that the device of loudspeaker array is set, it is characterized in that utilizing quadratic residue sequence that the device of loudspeaker array is set, drive the loudspeaker array signal source respectively through driving loud speaker behind the phase retardation device that meets above-mentioned requirements again:

When N=5, the phase delay of each loud speaker is respectively:

$0,\frac{2\mathrm{\π}}{7},\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}$

When N=7, the phase delay of each loud speaker is respectively:

$0,\frac{2\mathrm{\π}}{7},\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}\×2,\frac{2\mathrm{\π}}{7}\×2,\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}$

When N=11, the phase delay of each loud speaker is respectively:

$0,\frac{2\mathrm{\π}}{7},\frac{2\mathrm{\π}}{7}\×,\frac{2\mathrm{\π}}{7}\×9,\frac{2\mathrm{\π}}{7}\×5,\frac{2\mathrm{\π}}{7}\×3,\frac{2\mathrm{\π}}{7}\×3,\frac{2\mathrm{\π}}{7}\×5,\frac{2\mathrm{\π}}{7}\×9,\frac{2\mathrm{\π}}{7}\×4,\frac{2\mathrm{\π}}{7}.$

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