RU2515419C1 - Method of measuring change in course angle of probing signal source - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: method of measuring change in the course angle of a probing signal source involves successively receiving probing signals of a moving source; spectral analysis of the first, second and n-th received signals; in each of said received signals, determining the detection threshold, change in amplitude of spectral readings exceeding the threshold; determining and storing values of spectral readings F₁, F₂ and F_n, having maximum amplitude; calculating the difference between values of spectral readings F₂-F₁ and F_n-F₁; and the value of change in the course angle of the probing signal source $$Q_n^0$$

is defined as $$ar\cos Q_n^0,$$

where $$Cos{Q}_n^0=\left(Fn-F_1\right)/\left(F_2-F_1\right)<\mathrm{1,}$$

if the angle between the receiver and the source of probing signals increases, or $$Cos{Q}_n^0=\left(F_2-F_1\right)/\left(Fn-F_1\right)<\mathrm{1,}$$

if the angle between the receiver and source of probing signals decreases; and if (F_n-F₁)(F₂-F₁)=1, the course angle has not changed or has changed slightly.

EFFECT: determining motion elements of a probing signal source for multiple received transmissions.

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Description

The invention relates to the field of sonar and can be used to build systems for the detection of sonar signals (OGS) in modern sonar systems.

Probing signals emitted by sonars located on various carriers, including mobile ones, can be detected at long distances using well-known sonar signal detection systems (Yu.A. Koryakin, S.A. Smirnov, G.V. Yakovlev, “ Ship hydroacoustic equipment ”, St. Petersburg, Science, 2004, pp. 89-92). When these signals are detected, the problem arises of measuring the parameters of the sounding signal, as well as the task of determining the direction and directional angle of movement of the source of the sounding signal.

Known methods for detecting the location of the source of sounding signals described in the work of A. A. Prostakov "Hydroacoustic means of the fleet", M .: 1974, p. 90. The paper considers the problem of determining the location of a random target emitting pulsed signals when using multiple receiving posts. Differences in the time of sound arrival to each receiver are measured, which in turn correspond to differences in the distances from the sound source to the respective receivers. As you know, the geometrical location of the points, the difference of the distances of which to the receivers is constant, is a hyperbole. Having determined the intersection point of the calculated hyperbolas, you can find the place of the sound source and, accordingly, the distance to it, determine the next place of the signal source, construct the path of the source and determine the directional angle of the signal source.

In some cases, this problem can be solved using the triangulation method using several receivers or by evaluating several bearings (V. I. Dmitriev et al. “Navigation and Locations”, Moscow, 2009, p. 278.). Similarly, it is possible to determine the location of the probe signal source when receiving a series of pulses and during complex maneuvering, which requires a long operating time of the observed sonar and a long time of fixed maneuvering, which is not always possible and advisable (Collection "50 years of the Central Research Institute. Morphizpribor", St. Petersburg, 1999 G., p. 149. Yu.A. Koryakin, S. A. Smirnov, G. V. Yakovlev, “Ship sonar equipment, St. Petersburg, Nauka, 2004, p. 67.). However, this method is the closest analogue and can be taken as a prototype.

The method comprises the sequential reception of sounding signals emitted by the observed source, determining the time of arrival of the first received sounding signal, measuring the direction of arrival of the sounding signal, determining the change in the proper position of the sounding signal receiver, determining the speed of the sounding signal receiver, determining the time of receipt of the next sounding signal at a new point the location of the receiver, measuring the direction to the source of the probing signal at a new point the location of the receiver of the probing signals, the measured direction and the measured distance determine the position of the point of intersection of directions to the source of the probing signals, the sides of the triangle are determined by the two angles and side, which will be equal to the distances to the source of the probing signals at the moment of measuring the directions. By repeating the measurements and obtaining a new distance, it is possible to determine the speed of movement of the radiation source, and the direction of motion of the source of the probing signals, which is a characteristic of the directional angle of motion of the source of the probing signals relative to the receiver of the probing signals.

To implement this method, it is necessary that the source of the probe signal (sonar), the parameters of which are determined, operate continuously, and this does not always happen. Another disadvantage of this method is the need for a complex scheme of maneuvering the receiver of the probing signals, which requires a lot of time. During this time, the position of the moving sonar can significantly change, which will lead to an error in determining the heading angle of the signal source relative to the receiver.

The objective of the invention is to simplify the procedure for determining changes in the heading angle of motion of the source of the probing signal relative to the receiver of the probing signals.

The technical result of the proposed technical solution is the ability to determine the magnitude of the change in the heading angle of the sounding signal source relative to the sounding signal receiver based on several received sounding signals and their characteristic features.

определяют как $$ar\cos Q_n^0$$

, где $$Cos{Q}_n^0=\left(Fn-F_1\right)/\left(F_2-F_1\right)<1$$

, если источник зондирующих сигналов приближается, или $$Cos{Q}_n^0=\left(F_2-F_1\right)/\left(Fn-F_1\right)<1$$

, если источник зондирующих сигналов удаляется, а при (Fn-F₁)/(F₂-F₁)=1 считают, что курсовой угол движения не изменился или изменился незначительно.To achieve this technical result, additional features are introduced into the method containing the sequential reception of the probing signals of a moving source, namely: spectral analysis of the first, second, and nth received signals is performed, the detection threshold is determined in each of these received signals, and the amplitudes of the spectral samples are measured , exceeding the threshold, determine and store the values of the spectral readings F ₁ , F ₂ and F _n having a maximum amplitude, calculate the difference in the values of the spectral readings F ₂ -F ₁ and F _n -F ₁ , and the value of the change in the directional angle of motion of the source of the probing signals $$Q_n^0$$

determine how $$ar\cos Q_n^0$$

where $$Cos{Q}_n^0=\left(Fn-F_{\mathrm{one}}\right)/\left(F_2-F_{\mathrm{one}}\right)<\mathrm{one}$$

if the sounding source is approaching, or $$Cos{Q}_n^0=\left(F_2-F_{\mathrm{one}}\right)/\left(Fn-F_{\mathrm{one}}\right)<\mathrm{one}$$

if the source of the probing signals is removed, and if (Fn-F ₁ ) / (F ₂ -F ₁ ) = 1, it is believed that the directional angle of movement has not changed or has changed slightly.

Let us explain the achievement of the technical result.

As a rule, the operation of the sonar, which is the source of the probing signal, has as its aim the survey of space and the detection of an object by the presence of an echo signal from it. The propagation range of the probing sonar signal is significantly greater than the detection range of the reflected echo signal. Therefore, the probe signal is detected by the receiver of the OGS system almost always with the first radiation signals, the probability of skipping such a direct propagation signal is extremely small. Radiation of the probe signal occurs at fixed points along the distance when the source (sonar) is moving, after a certain time interval, the value of which is selected depending on the scale of the sonar and is determined by the frequency of the probe signal or the duty cycle of the radiation.

In hydroacoustics, and in radar, the “Doppler effect” is known, which consists in the fact that when the source or receiver moves, the frequency of the radiated probe signal differs from the frequency of the received signal (A.S. Kolichedantsev, Hydroacoustic stations. Sudostroenie, L., 1982 city, p.21).

и с учетом следующего зондирующего сигнала $$F_n-F_1=F_{1}V\cos Q_{n1}^0/C$$

. Разделим правые и левые части независимых уравнений и получим:You can write: F ₂ = F ₁ + F ₁ V / C, where F ₁ is the frequency of the emitted signal, F ₂ is the frequency of the received signal, V is the speed of movement, C is the speed of sound. This is true if the source moves directly in the direction of the receiver. However, in most cases, the movement occurs at an angle and then the speed of movement refers to the approach speed or the radial component of the initial speed, which is determined by the angle between the direction of movement and the direction between the source and receiver. Then F ₂ = F ₁ + F ₁ VcosQ ⁰ / C or after conversion $$F_2-F_{\mathrm{one}}=F_{\mathrm{one}}V\cos Q_{21}^0/C$$

and taking into account the following sounding signal $$F_n-F_{\mathrm{one}}=F_{\mathrm{one}}V\cos Q_{n\mathrm{one}}^0/C$$

. Separate the right and left sides of the independent equations and get:

. $$\left(F_n-F_{\mathrm{one}}\right)/\left(F_2-F_{\mathrm{one}}\right)=\left(F_{\mathrm{one}}V\cos Q_{n\mathrm{one}}^0/C\right)/\left(F_{\mathrm{one}}V\cos Q_{21}^0/C\right)=\cos Q_{n\mathrm{one}}^0/\cos Q_{21}^0$$

.

The frequency of sonar radiation is not known; if it were known, then the course angle of the sonar could be measured. Therefore, the magnitude of the change in the heading angle of the probe signal relative to the receiver is determined, and the measured frequency of the first received probe signal is taken as frequency F ₁ . If we take into account that the change in the angle on the first premises is smaller than on the subsequent ones, we can assume that the estimate of cosQ ₂₁ is close to 1, and then we obtain:

(F _n -F ₁ ) / (F ₂ -F ₁ ) = cosQ _n1 , where F ₁ is the frequency of the first received signal, and Q _n1 is the magnitude of the change in the heading angle during the time between packets 1 and n. The accuracy of the estimate of the change in the directional angle of motion of the source of the probing signals will depend on how much the frequency F ₁ differs from the initial radiation frequency.

In real conditions, the initial direction of sonar movement directly to the receiver is rare. Therefore, an estimate of the magnitude of the change in the course angle of the source of the probing signals obtained from the calculation results will differ from the true magnitude of the change. Nevertheless, the fact of a change in the direction of movement will be measured, the estimated value of the change in the course angle of the sonar, the value of which will improve with each new received parcel. If (F _n -F ₁ ) is less than (F ₂ -F ₁ ), this means that the directional angle of the sonar in relation to the receiver increases. If (F _n -F ₁ ) is greater than (F ₂ -F ₁ ), then the course angle of the sonar relative to the receiver decreases. In this case, to calculate the magnitude of the change in the heading angle of the sounding signal source, it is necessary to take the reciprocal of the value obtained and in relation to it to determine the change in the heading angle of the sounding signal source. If (F _n -F ₁ ) = (F ₂ -F ₁ ), this means that the directional angle of the sonar in relation to the receiver has not changed. As a rule, the repetition rate of probing signals from search sonars is quite high. During the time between emissions, the sonar will not significantly change its location and therefore, on the first transmissions, the frequency will not change significantly. Therefore, the frequency measurement is performed for each received package, the frequency difference is estimated for each subsequent signal, the ratio is calculated each time to the first measured frequency difference, which with each received signal leads to an increase in the reliability of the measured change in the directional angle of movement.

The invention is illustrated by the drawing, which shows a block diagram of a device that implements the proposed method.

The device comprises an antenna 1 connected via a receiving device 2, a spectral analysis unit 3 with a first input of a measurement unit 5 of a spectral reference value with a maximum amplitude. The output of block 5 is connected to the input of memory block 6, the first output of which is connected to the first input of decision block 9. The second output of block 3 through the threshold selection block 4 is connected to the second input of block 5. The second output of block 6 through the difference calculation block 7 and block 8 for calculating the value of the angle of change of course is connected to the second input of the decision block 9.

An example of the proposed method, it is advisable to consider together with a description of the operation of the device that implements the method.

The probe signals received by the antenna 1 are sent to the receiving device 2, where they are detected and transmitted to the block 3 of the spectral analysis. These blocks are well-known devices that are implemented in the prototype and in sonar signal detection systems (Yu.A. Koryakin, S.A. Smirnov, G.V. Yakovlev, Ship sonar equipment, St. Petersburg: “Science”, 2004, S.89-92). From the output of block 3, the spectrum readings of the selected probe signal are sent to block 4, where they are compared with a threshold, after which, in block 5, the spectral reference with the maximum amplitude is determined. The probing signals received by the sonar detection equipment are direct propagation signals and therefore are processed at the receiving device with a large signal-to-noise ratio, therefore there is no problem of choosing a threshold in this situation. At the output of block 3, the samples of the spectrum can have different values and different amplitudes, in addition, to solve the problem, it is necessary to select samples in frequency and amplitude. This problem is solved in block 4, which generates a threshold signal in amplitude and threshold signal boundaries in frequency. The selected samples of the spectrum enter the block 5 for determining the spectral reference with a maximum amplitude, where the values of the frequencies whose amplitude is maximum for the received sounding signal are selected. The value of this spectral reference and the number of the probe signal with the detection time from block 5 are transferred to memory block 6, where the spectra are selected in time and in pairs. The selected pairs of spectral samples are sent to block 7 for calculating the difference and calculating the ratio of the measured difference to the first difference, which is stored in the same block. After this, the determination of the cosine of the angle and the determination of the magnitude of the change in the directional angle of the source of the sounding signals. All these parameters go to decision block 9, where they are displayed and used to form the sonar motion path of the probing signals.

All these computational operations, the operations of storing, selecting and comparing, can be carried out in special processors used to detect probing sonar signals during software development (ibid., Pp. 281-295).

Thus, without maneuvering, only by measuring the difference in spectral readings between the methods of the probing signals and calculating their ratio, as well as using simple mathematical operations on them, it is possible to determine the change in the course angle of the moving source of the probing signal and track its direction of movement.

Claims (1)

A method of measuring a change in the directional angle of motion of a source of sounding signals, comprising sequentially receiving the sounding signals of a moving source, characterized in that: a first, second and n-th received signals are spectrally analyzed, a detection threshold is determined in each of these received signals, and the amplitudes of the spectral samples are measured , exceeding the threshold, determine and store the values of the spectral readings F ₁ , F ₂ and F _n having a maximum amplitude, calculate the difference in the values of the spectral readings F ₂ -F ₁ and F _n -F ₁ , and the value of the change in the course angle of motion of the source of the probing signals $$Q_n^0$$

determine how $$ar\cos Q_n^0$$

where $$Cos{Q}_n^0=\left(Fn-F_{\mathrm{one}}\right)/\left(F_2-F_{\mathrm{one}}\right)<\mathrm{one}$$

if the angle between the receiver and the source of the probing signals increases, or $$Cos{Q}_n^0=\left(F_2-F_{\mathrm{one}}\right)/\left(Fn-F_{\mathrm{one}}\right)<\mathrm{one}$$

if the angle between the receiver and the source of the probing signals decreases, and when (Fn-F ₁ ) / (F ₂ -F ₁ ) = 1, it is assumed that the directional angle of movement has not changed or has changed slightly.