SU1088513A1 - Method of bistatic acoustic atmospheric sounding - Google Patents

Abstract

THE METHOD OF THE BYSTATIC ACU. STOMIC SENSING OF THE ATMOCIEPLI according to which a pulse of acoustic radiation is sent to the investigated area of the atmosphere, receive a scatter of Hde radiation and record the time interval between the sending and receiving them. acoustic radiation pulse, which is judged by the meteorological parameters of the atmosphere, differing in that. what. The invention relates to meteorological instrumentation and can be used to remotely measure air temperature, wind speed and direction. The known method of bistatic acoustic sounding of the atmosphere, according to which a sound wave is sent to the investigated region of the atmosphere, the scattered wave is received by a system of a ring of microphones and the air temperature and wind speed are judged by the time delay of the sound pulse. in order to increase the accuracy of sounding, during the time of sending an acoustic radiation pulse, the angle between the direction of the acoustic radiation pulse sending and the direct connecting emitter and receiver with a speed of Co (P-1) Vd sln (a-fj8), rad / s, cos а - (sin «+ sin p) ctg (a -fp) where P is a given dimensionless parameter, .. Co is the speed of sound on ground level; d is the distance between the emitter and receiver. .. Ogs ft are the angles between the straight line connecting the emitter and receiver, and the axes of the transmitting and receiving system radiation patterns at the moment of time, coinciding with the center of the time interval for sending the pulse. O 00 IOO Due to the ambiguity of the path, the sound was transmitted within the limits of the antenna directivity diagrams, the accuracy of the known method is low. The closest to this technical solution is the method of bistatic acoustic sounding of the atmosphere, according to which a pulse of acoustic radiation is sent to the studied area of the atmosphere, receive scattered radiation and record the time interval between the sending and reception of a pulse of acoustic radiation, according to the magnitude of which judge the atmospheric meteorological parameters .

Description

However, the known method has a low accuracy of sounding due to the broadening of the duration of the received sound pulse due to the unique significance of the path traveled by the sound pulse. The purpose of the invention is to improve the accuracy of sounding. For this, in the known method of bistatic acoustic sounding of the atmosphere, according to which an acoustic radiation pulse is sent to the investigated area of the atmosphere, my radiation is scattered, and the time interval between the transmission and reception of the acoustic radiation pulse, measured according to the atmospheric meteorological parameters, is recorded. Acoustic radiation pulse guiding time reduces the angle between the direction of the acoustic radiation pulse on the direct connecting-emitter and receiver with speed v - s- -Q - :: cos о; - sin (X -1- sin / j where P is the given dimensionless parameter,. Co is the speed of sound at ground level; d is the distance between the transmitter and the receiver; a and angles between the straight line connecting the transmitter and the second. k, and the axes of the transmitting and receiving antenna patterns at the moment of time, coinciding with the center of the time interval for sending the pulse. Fig. 1 is a schematic diagram explaining the method of biostatic acoustic sounding; Fig. 2 shows a device implementing the method. The sound emitter T emits a pulse to the investigated area of the atmosphere. from acoustic radiation at angles a to the direct connecting the radiator, sound T and receiver F. The diffuse radiation is received at an angle j to the same straight line at distance a. For fixed emission and reception angles a and / h, an acoustic pulse radiation duration TU emitted in solid angle 1p due to the difference in paths traveled by the sound wave will be increased by the value of A L / C, where A L LI- Ls AB + BC, C is the speed of sound. As a result, the accuracy of the measurement of the time interval between the moment and reception of the pulse determined by the duration of the received the impulse gp gi -f-al / c cannot be increased only by decreasing T. Reducing Ki makes sense only to a value comparable to AL / C. The reduction of the solid angle 1 / is also limited by the maximum dimensions of the acoustic antennas and the signal frequencies. With a decrease in the angle a in the course of the time Gu is sent to the pulse of acoustic radiation, the received scattered pulse temporarily compresses. In the direction at an angle a L-}) / 2 to which the longer propagation path of the sound Li corresponds, the radiation is sent earlier, and in the direction. At an angle a-rip / 2, in which the path L2 is shorter, later. As a result, the scattered wave arrives at the point greeted by F. along the paths of Li and La with a smaller delay relative to each other. If we denote by P the compression coefficient of the received scattered pulse P - P of the acoustic radiation - the duration of the received scattered pulse with decreasing of the angle a it is not difficult from the geometric relations in the drawing to obtain the required rate of decrease of the angle a - C (P-1) d (go) +., cosG: (to) - sin a (Ib jctg "(to) -f / j Maximum reduction rate angle a is determined by physical limitations. For example, when using tea The maximum speed of V is determined by the duration Tz of the scanning sector Att and the wavelength of the acoustic radiation. In this case, the maximum value of the parameter P does not exceed 50. Figure 2 shows a device that implements this method, where I is a synchronizer , 2 - transmitter, 3 - antenna with frequency scanning of the beam beam, 4 - antenna, 5 - receiver, b - time interval meter, 7 - mini-computer. Transmitter 2, controlled by signals from synchronizer 1, generates powerful pulses of the duration Gu of electrical oscillations with a linearly varying purity of the sound range and a time interval between them Tn longer than the acoustic propagation time of the PS sounding path. These oscillations by the frequency-scan antenna 3 are converted into sound waves and sent to the atmosphere in a direction varying in proportion to their frequency. The scattered sound pulses in the atmosphere are received by another antenna 4, spaced apart from the first by distance d, converted into an electrical signal, which is fed to the receiver 5, where it is amplified, filtered from the background noise and detected. Next, the envelope of the received signal enters the time interval meter b, which measures the difference in time between the arrival of the received pulse and the reference pulse from the synchronizer, which coincides in time with the center of the interval of the sending pulse, and provides information on the mini-computer 7 in the binary code, which allows determining the meteorological parameter by the memory algorithm. In addition, from the synchronizer to

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the receiver also receives a signal to prohibit the time of sending the probe pulse. Compared with the prototype, when probing according to the claimed method, the accuracy of measurements at the same range increases approximately 50 times. No deterioration in the signal-to-noise ratio occurs. Therefore, with a given maximum measurement error, the invented method also significantly increases the maximum sensing range, since it allows reliable measurements at a longer range, where the signal-to-noise ratio is less. This is achieved by degrading the spatial resolution from 20 m in the prototype to 40 m in the inventive method. However, the spatial resolution of 40 m is also sufficiently high and not attainable by the instruments currently used in meteorology.

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Claims (1)

(54X57) METHOD OF BYSTATIC ACOUSTIC SENSING OF THE ATMOSPHERE, according to which a pulse of acoustic radiation is sent to the investigated area of the atmosphere, receive scattered radiation and record the time interval between the sending and receiving. pulse of acoustic radiation, the largest of which is judged on the meteorological parameters of the atmosphere, characterized in that