DE102007022055B3 - A method for locating noise sources of a vehicle moving at a distance - Google Patents

Abstract

A method for locating noise sources of a vehicle (1) moving at a long distance comprises the following steps: - providing an array (2) with acoustic sensors; - Providing acoustic transmitters (4, 5, 6) on the vehicle (1) for generating an orthogonal reference signal (7); - Synchronization of the acoustic transmitter (4, 5, 6) and the acoustic sensors (3) with an absolute reference time; - Correlation of the received signals with the reference signals (7); - Determining the absolute acoustic position of the noise sources and the relative orientation of the noise sources by triangulation. This avoids the disadvantages of the known prior art solution and provides an improved solution for locating sources of noise from a vehicle traveling at a great distance. In addition, the invention provides a simple and inexpensive solution that dispenses with the access of external measuring stations, such as radar stations.

Description

The The invention relates to methods for locating noise sources a moving vehicle at a distance. Further concerns the invention a system for locating noise sources one in big Distance moving vehicle.

Out The prior art discloses methods for source localization of noise sources known on vehicles.

That's how it describes DE 199 10 329 A1 a method for determining the exterior noise of vehicles in an acoustic test bench. The following steps are proposed for a more precise determination of the proportion of an individual noise source in the pass-by noise: Determining a sound field caused by the entirety of the individual sound sources of the vehicle when driving by means of near-field microphones mounted on the vehicle and far-field microphones arranged in the test bench. Determining a sound field caused by loudspeakers when the vehicle is at rest, wherein the loudspeakers are arranged at positions or in the vicinity of the position of the individual sound sources of the vehicle, detects at least one variable characterizing the respective loudspeaker operation and the loudspeakers are put into operation successively. Calculate the parameters characterizing the loudspeaker operation which are necessary for simultaneous generation of the driving sound from the first step and calculation of a sound pressure level generated by a single sound source at a specific microphone product in the field. In this way, an exact determination of the proportion of individual individual noise sources on the pass-by noise of a road vehicle is to be made possible. A position determination, as required for vehicles in the long distance, does not take place here. Also, atmospheric disturbances are excluded by the measurement in a defined test environment.

Further, the US Pat. No. 7,054,228 B1 Method for localization and quantification of noise sources using arrays of acoustic vector sensors. In an evaluation device here the sound pressure and the noise intensity are determined, which should allow a direction determination of the noise source. The approximate spatial coordinates of the noise source are determined by means of a quadratic triangulation formula. Hereby a flying plane can be located and tracked as well as its noise volume can be determined. A determination of different noise sources on the aircraft itself is not possible with this method, since for this purpose the absolute location of the aircraft flying past at a great distance is too imprecise and this can only be reproduced as a coordinate point.

A Another known method for determining the noise sources of an aircraft in overflight is in Piet, J.F. et al. "Localization of the Acoustic Sources of the A340 with Large Phased Microphone Array during Flight Tests ", American Institute of Aeronautics and Astronautics, Paper 2002-2506, p. 1-11 described. Therein, the use of a microphone array is provided. The noise measurement is there with a very accurate determination of the aircraft position and the aircraft location connected by GPS data or by radar technology he follows. The accuracy should be in the order of magnitude of the wavelength. Disadvantage of this known method is that electromagnetic Waves used to determine the position of the aircraft, the not the change the local speed of sound due to atmospheric fluctuations such as wind, Temperature, etc. are subjected. The disadvantage of position determination By means of GPS, radar, radio, etc., it is therefore that electromagnetic Waves are used. These electromagnetic waves are spreading different than the sound waves to be measured, d. H. it will indeed determines the geometric position exactly, but the relevant "acoustic" position becomes only inaccurately determined. This often focuses the microphone array an incorrect position and the results of the source localization the source of noise are practically unusable.

Of the The invention is therefore based on the object, the disadvantages of the known solutions to avoid the prior art and an improved solution to Locate sources of noise one z. B. in large Distance moving vehicle to provide. It should also by the invention further provides a simple and inexpensive solution are the access to external measuring stations, such as Radar stations omitted.

These The object is achieved by a Method for locating sources of noise at a great distance moving vehicle with the features of claim 1 and a system for locating sources of noise at a great distance moving vehicle with the features of claim 10. advantageous Embodiments and developments of the solution according to the invention are in the dependent claims specified.

• – Bereitstellen eines Arrays mit akustischen Sensoren;
• – Bereitstellen von akustischen Sendern am Fahrzeug zum Erzeugen eines orthogonalen Referenzsignals;
• – Synchronisation der akustischen Sender und der akustischen Sensoren mit einer absoluten Referenzzeit;
• – Korrelation der empfangenen Signale mit den Referenzsignalen;
• – Bestimmen der absoluten akustischen Lage der Geräuschquellen sowie der relativen Orientierung der Geräuschquellen durch Triangulation.

The method according to the invention for locating noise sources of a vehicle moving at a distance has the following steps:

• - providing an array with acoustic sensors;
• - Providing acoustic transmitters on the vehicle for generating an orthogonal reference signal;
• - synchronization of the acoustic transmitters and the acoustic sensors with an absolute reference time;
• - Correlation of the received signals with the reference signals;
• - Determining the absolute acoustic position of the noise sources and the relative orientation of the noise sources by triangulation.

hereby become the disadvantages of the known solutions of the prior art avoided and an improved solution for locating noise sources a remotely moving vehicle provided. Furthermore The invention provides a simple and cost-effective solution to disposal placed on the access of external measuring stations, such as Radar stations, omitted. In particular, the vehicle can in relatively large Distance, for example, if it is a passing aircraft or it may be located at a relatively short distance, for example, in the case of a close measurement on a helicopter, wherein z. B. also flow acts.

According to the invention for the Location and for the orientation, d. H. For the angle of rotation or orientation, acoustic reference sources used. These send out orthogonal acoustic signal sequences. These signal sequences can for example, chirp signals, bar codes, gold codes, etc. By means of these reference signals then the acoustic position of the vehicle can be determined exactly. A special advantage is in that both the locating signals and the measuring system on acoustic Spread. This means, the location taken into account automatically all phenomena the atmospheric Wave propagation or ground and terrain effects such as reflections, etc., and lets it go an exact position determination too. Furthermore, there are no additional ones Measuring or auxiliary systems required. In particular, deleted the determination of the absolute position for example by means of radar, for this the inventive method the determination of the acoustic relative position is sufficient.

A advantageous development of the invention provides that the acoustic Sensors are designed as microphones. These have turned up at the noise measurement as reliable and versatile. In particular, microphones allow the measurement to continue Frequency ranges and thus provide a wealth of raw data for further Evaluation.

Yet An advantageous development of the invention provides that the orthogonal reference signals are coded differently. hereby The reference signals can be individual components on the vehicle and thus assign defined positions.

A Further advantageous development of the invention provides that the acoustic transmitters as speakers or other suitable electromechanical Transducers are formed whose extension is small compared to the respective wavelength is. Here, in particular, small designs are used, so the transmitters do not have the flow behavior unfavorable influence.

Yet A further advantageous embodiment of the invention provides that at least three transmitters are provided on the vehicle. hereby settles in easy to perform a position determination that is less than three Transmitters is more complex.

Further provides an advantageous development of the invention that the moving vehicle a flying object, especially an airplane, in overflight is. This is where the invention comes into its own, as the distances between the vehicle and the array are particularly large here. But also noise sources from passing by in the distance or watercraft can advantageously be located with this method.

A Another advantageous embodiment of the invention provides that the viewing direction of the array over a time delay is controlled at each acoustic sensor. This is from a Controlled evaluation device.

A advantageous development of the invention provides that a cross-correlation from the orthogonal sequence of the signal and a pattern comparison. This allows the measurement results to be refined or verified.

Finally sees an advantageous embodiment of the invention that a determination the damping the signals due to the propagation due to the orthogonal reference signals he follows. Thus, by using standard sources, i. H. by Power normalization, also the damping of the signal determined by the propagation.

One inventive system for locating noise sources one in big Distance moving vehicle has an acoustic array Sensors, acoustic transmitters on the vehicle for generating orthogonal Reference signals and an evaluation unit. It can the Evaluation unit as a digital computing unit with real-time operation be designed.

Further the invention improving measures will be described below together with the description of a preferred embodiment the invention with reference to the attached Figure closer shown. The figure shows a schematic perspective view of an aircraft in overflight over a corresponding measuring field.

Therein is schematically an airplane 1 shown, which moves in the direction of the arrow at a speed v in the plane of the drawing from left to right. The plane overflows 1 a microphone array 2 consisting of about 60 microphones arranged in crossed lines 3 is constructed. Here is each of the microphones 3 precisely defined and precisely locatable in an xy grid.

At the plane 1 are in the present embodiment, three acoustic transmitter 4 . 5 . 6 arranged. There is a transmitter on the left wing tip 4 , at the right wing tip a transmitter 5 and in the bow a transmitter 6 arranged. The transmitters 4 . 5 . 6 are designed as speakers, the differently coded orthogonal reference signals 7 send out. The emitted signal sequences of the orthogonal signals 7 may be chirp signals, bar codes, gold codes or other suitable signal sequences. Due to the different coding, every reference signal is 7 the corresponding aircraft component and thus the position on the aircraft 1 assignable.

The orthogonal reference signals 7 are synchronized with the reference time of the microphone acquisition at the beginning of the measurement campaign. This is essential because only then can the signal propagation time be determined correctly.

By correlation of the received signals 7 With the references on the ground, the acoustic duration of each transmitter can be determined for each microphone. From this triangulation follows both the absolute acoustic orientation and the relative orientation, ie tilting or tilting.

In addition to the reference signals 7 The other sounds generated by the flying aircraft are also detected by the microphone array according to their different position. These are for example engine noise, interference of aerodynamic components, reflected sound waves, etc.

As the measurement and location of the reference signals 7 and the sound waves of the aircraft noise are based on the same wave propagation, runtime fluctuations, which are generated for example by atmospheric disturbances such as temperature layers or wind, are deliberately included in the measurement. This orients the microphone array 2 automatically to the acoustically relevant position of the moving aircraft 1 ,

The microphone array 2 works like a classic array as a beamformer. The viewing direction of the array is controlled by a time delay on each microphone. This viewing direction is in the sense of this invention from the position determination on the transmitter 4 . 5 . 6 on the moving plane 1 certainly.

The synchronization of the transmitter 4 . 5 . 6 and the microphones 3 as well as the signal detection and evaluation via a (not shown) evaluation unit. In the present exemplary embodiment, this is a digital arithmetic unit in real-time operation. But it is also possible to make an offline evaluation or later evaluation of the signals. In the evaluation unit can also cross-correlation of Orthogonalfolgen the reference signals 7 and the pattern comparison of the signal coding.

The Restricted invention in their execution not to the preferred embodiment given above. Rather, a number of variants are conceivable, which of the in the claims claimed solution also in other types Use.

1

plane

2

microphone array

3

microphone

4

transmitter

5

transmitter

6

transmitter

7

reference signal

Claims (10)

Method for localizing noise sources of a vehicle moving at a distance ( 1 ), the method comprising the following steps: - providing an array ( 2 ) with acoustic sensors; - Provision of acoustic transmitters ( 4 . 5 . 6 ) at the vehicle ( 1 ) for generating an orthogonal reference signal ( 7 ); - Synchronization of the acoustic transmitters ( 4 . 5 . 6 ) and the acoustic sensors ( 3 ) with an absolute reference time; Correlation of the received signals with the reference signals ( 7 ); - Determining the absolute acoustic position of the noise sources and the relative orientation of the noise sources by triangulation. Method according to claim 1, characterized in that the acoustic sensors ( 3 ) are designed as microphones. Method according to claim 1, characterized in that the orthogonal reference signals ( 7 ) are coded differently. Method according to claim 1, characterized in that the acoustic transmitters ( 4 . 5 . 6 ) are designed as speakers or other suitable electromechanical transducer whose extent is small compared to the respective wavelength. Method according to claim 1, characterized in that at least three transmitters ( 4 . 5 . 6 ) at the vehicle ( 1 ) are provided. Method according to claim 1, characterized in that the moving vehicle ( 1 ) a flying object, in particular an aircraft, is in overflight. Method according to claim 1, characterized in that the viewing direction of the array ( 2 ) over a time delay on each acoustic sensor ( 3 ) is controlled. Method according to claim 1, characterized in that a cross-correlation from the orthogonal sequence of the reference signal ( 7 ) and a pattern comparison. A method according to claim 1, characterized in that a determination of the attenuation of the signals by the propagation due to the orthogonal reference signals ( 7 ) he follows. System for locating noise sources of a vehicle moving at a long distance ( 1 ) according to a method according to one of claims 1 to 9, wherein this an array ( 2 ) with acoustic sensors ( 3 ), acoustic transmitters ( 4 . 5 . 6 ) at the vehicle ( 1 ) for generating orthogonal reference signals ( 7 ) and an evaluation unit.