Apparatus and method for determining direction of audio source by diver

FIELD: physics.

SUBSTANCE: signal from a source is received at two nondirectional antennae at a distance of λ/4 from each other. The signal from the first antenna is transmitted to the input of an automatic gain control (AGC) amplifier and the signal from the other antenna is delayed by a quarter-period is summed up with the signal from the first antenna. The summation results in formation of a cardioid-type beam pattern. The resultant signal is transmitted to the control input of the AGC amplifier, the gain of which is inversely proportional to the control signal level. As a result, a signal reaches the headphones of the diver, said signal becoming maximum if the diver turns such that the line connecting the right and left side antennae turns in the direction of the source.

EFFECT: broader functionalities, simpler and smaller size of the apparatus.

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The invention relates to a gear diver and can be used as an element in a communication, management and control when performing underwater operations, when actions related to the military sphere, in emergency situations, as well as divers and lovers.

When placed in an aqueous environment at distances of tens or hundreds of meters from providing a surface vessel only means of communication diver is a link on the hydroacoustic channel. One of the most important elements of this communication system is a system which enables the diver to determine the direction to the source of acoustic (sound) signal. The source of this signal may be the signal radiation from the provider, from a special sonar beacon or from another diver for group action. The determination of the direction to the source audio signal is implemented using sonar signal, diver, which is part of his equipment.

The direction finder diver must meet two basic requirements:

the direction finder must be fully, with all component parts, to integrate into wearable diver equipment without creating additional discomfort when performing work;

the accuracy of determining the direction to the signal source should be sufficient for unambiguous the selection of this direction and amount to 15-20° [1].

The direction finder must operate in the frequency range corresponding to the frequency range of the signals used by divers 8-35 kHz.

To create directional characteristics (XH), providing the necessary accuracy of direction finding, the size of the acoustic aperture of the antenna should be approximately (2...3)λ (λ is the wavelength of the operating frequency processed signal), i.e. for the above frequencies from 9 cm (f=25 kHz) to 37.5 cm (f=8 kHz). Even if it will be possible to place the antenna of the required size on the body of the diver, to perform direction finding in two planes will be difficult.

Known methods and devices that partially solve the problem of the direction finder for divers.

Thus, in the device according to U.S. patent [2] the system of diving equipment that solves the problems of navigation, is placed on the helmet and has electronic and computer means, including a display, which displays information needed by the diver, the diver can determine its position relative to the source signal only in the presence of external systems to ensure the vessel. This system, in turn, must have reasonably accurate data on the location of the diver.

In U.S. patent [3] on the helmet diver install multiple receivers, components of the phased array airborne early warning antenna array (PAA). The location of the HEADLIGHTS with the desired orientation is within a helmet is unlikely to work at frequencies below 15 kHz. In addition, using linear HEADLIGHTS can provide direction in one plane only, and multi-channel processing system much more complicated.

In the utility model [4] proposed to implement the correlation processing of signals from two antennas, but HN is formed only in the horizontal plane and in a vertical plane, the system is non-directional.

The closest technical and functional characteristics of the present device and method is "direction finder diver" on the application [5]. This device and method of direction finding using the specified device adopted for the prototype.

The device prototype consists of two identical channels, each of which has connected in series aimed acoustic antenna amplifier with automatic gain control (AGC) and head phone. The antenna is directed in the left and right hemisphere relative to the longitudinal axis of the diver and fixed to the body (helmet) diver. The outputs of the antennas connected to the input device selecting the maximum signal, and the output of this device is connected to the control inputs of the amplifiers with AGC device channels of the prototype. The gain of amplifiers with AGC becomes maximum when the signal levels on both inputs (signal and control) are the same. In the analog, where the signal level of the acoustic antenna is less, will be smaller and the gain of the amplifier, and therefore this channel to the appropriate head phone will receive a signal of a smaller level than the other. It is assumed that the diver compares beeps in the headphones and turns up until the signals in both channels will not be equal. So the diver determines the direction of the signal source.

Device-prototype [5] has a number of disadvantages:

as already mentioned, the implementation of directional reception requires a large amount of aperture of the receiving antenna; minimum focus has antenna with XH type of the hemisphere, but also the implementation of the acoustic antenna with HN in the form of a hemisphere requires a large area screening surface (up to ten wavelengths at the frequency of the processed signal) [6];

- in the case of the HN type, hemisphere device prototype provide a direction finding signal source is fundamentally accurate to the plane perpendicular to the line connecting the centers of the antenna, but the signal source may be above/below the diver, and this localization is impossible;

the sensitivity of each ear of the diver may be different, including the frequency required an additional adjustment of the amplitude-frequency response of each channel for a specific user is on of the motor.

The technical result of the proposed device and method of its use is

- the possibility of finding the diver audio source coming from any direction in space (two angular coordinates);

- decreased size of acoustic antennas, so that they can easily be placed on the helmet of a diver;

- the rejection of the use of binaural effect, i.e. the mapping of the signals arriving at each ear of the diver;

- reduction apparatus using only one amplifier with AGC and one phone.

To achieve the claimed technical result in the device definition diver directions on the audio source (SFL), containing two (acoustic) antenna tract listen to the received signals, comprising serially connected first antenna amplifier with automatic gain control and a headphone, and the tract provide a control voltage for the amplifier with AGC, introduced new features:

antenna is made non-directional;

centers of antennas placed at a distance of a quarter wavelength of the carrier frequency of the received signal;

the tract provide a control voltage for the amplifier with AGC consists of a unit delay signal for a time equal to a quarter period of the carrier frequency of the received signal, and adder;

the output of the first antenna is connected to the signal input of the amplifier with AGC and to the first input of the adder;

a second antenna connected in series with the delay device and the second input of the adder;

the output of the adder is connected to the control input of the amplifier with AGC, the gain of which is made inversely proportional to the level of the control signal.

For the convenience of finding the source of the audio signal, the first antenna is located on the helmet of a diver on the line from the nose to the back side of the nose.

In the method of determining the diver directions on the audio source (SFL), consisting of Desk diver level signal based on the reception signal SFL two spaced antennas and deciding on the direction of SFL, introduced new features:

the output signal from the second antenna is delayed for a time equal to a quarter period of the carrier frequency of the received signal (τ=T/4);

- delayed signal summed with the signal received from the output of the first antenna;

- for making decisions about the direction of the sound source signal using the signal of the first antenna, and the level of this signal change is inversely proportional to the value of the level of the total signal;

- change the spatial position of the imaginary line connecting the CE the format of the antennas change in space the position of the diver to achieve the maximum level recorded by the diver signal;

- determine the direction of SFL as the direction of the vector from the location point of the second antenna to the location of the first antenna.

The invention is illustrated figure 1-3. Figure 1 presents a generalized functional diagram of the inventive device; figure 2 shows the directional characteristic, which is formed after the adder; figure 3 shows the resulting HN, representing up to a constant angular distribution of the signal, listening to the diver.

The proposed device (figure 1) consists of an array of acoustic antennas 1, 2, which are denoted by A₁and A₂; antenna placed at a distance of λ/4. Structurally antenna, made each in the form of omnidirectional hydrophone can be placed on the helmet of a diver above the surface of the helmet to reduce the influence of diffraction. The antenna output is A₂connected channel 3 provide a control voltage for the amplifier with AGC, which includes the device 4 delay (denoted in figure 1 as τ), serially connected with the second input of the adder 5 (denoted by Σ); output antenna A₂connected to the signal input of the amplifier 6 with AGC and to the first input of the adder 5. The output of the adder is connected with the control input of the amplifier 6 and the output of the amplifier - head phone 7 diver. All of the included device nodes from the given in figure 1, known [1, 6].

The operation of the device and steps of the claimed method of direction finding is useful to consider together.

Let the signal of the sound source with the carrier frequency f, comes with directions, as shown by the double arrow in figure 1. Identical antennas A₁and A₂are omnidirectional (shielding the body of a diver in this case is not considered), so the signal coming from any direction in space, will be perceived by the diver. To improve the formation of the Omni-directional HN hydrophones, which consist of the antenna can be raised above the helmet diver. The distance between the antennas is equal to λ/4, so the phase shift in accordance with [6] between the signals arriving at the antenna of A_1,2will kd cosθ, where k=π/λ=2πf/c, where c is the speed of sound in water; d is the distance equal to λ/4, θ is the angle between the line connecting the centers of the antennas, and the direction of the signal source (for the case shown in figures 1, 3, θ=0). Thus, the phase shift between the signals at the outputs of the antennas will be.

The signal from antenna A₁is supplied to the signal input of the amplifier 6 with AGC, and the signal from the antenna And₂shifted at time f=T/4, T=1/f; which gives an additional phase shift Δφ₁=2πft=2πfT/4=π/2. At the first input of the adder 5 receives the signal with the phase φ₁=0, and the second input signal, the moved phase angle φ ₂=π(1+cosθ)/2. After summation of these signals at the output of adder is signal, the angular distribution is described HN

and has the shape of a cardioid [6] (figure 2). Axis cardioid lies on the line connecting the centers of the antennas, and the maximum is facing, which is directed vector from antenna 1 to antenna 2. Zero cardioid facing in the opposite direction, in the figure 2 example, "0" cardioid facing in the direction of signal arrival.

The signal is described by expression (1), is fed to the control input of the amplifier 6 with AGC, and the signal input of the amplifier 6, the video signal from the antenna A₁1. The gain of the amplifier 6 is such that the higher the level of the control signal, the lower the signal level at the input of the phone 7. Therefore, HN output signal from the amplifier 6 can be represented by the function ("return cardioid")

Figure 2 shows the ideal cardioid. When the direction θ=0, the function R_ARU(θ) degenerates to a δ-function and the value function (2) must be infinite. In real poliocephalus situation are destabilizing factors (noise of different origin), so the level cardioid (1) in the direction θ=0 R(θ)|_θ=0≠0, i.e. there is a "swimming" zero HN. The inverse function R_ARU(θ), respectively, the ri θ=0 will not be in the form of δ-functions, and will be limited in size, as shown in figure 3.

From figure 3 it is seen that the angular distribution of the signal coming in on the phone diver, depends on the direction of arrival of a signal and has a pronounced maximum in the direction θ=0 along the line coincident with the line connecting the centers of the antennas A₁and a₂and the direction vector of the source signal coincides with the vector going from the center of the antenna A₂to the center of the antenna A₁.

When no signal diver listens to the ambient noise, which can be considered isotropic. When the presence of a signal the diver rotates the helmet to achieve the maximum level of the signal in the phone. Depending on the relative position of the antenna (from the face to the back or along the line of the shoulders of the diver) diver turns his face (sideways), delengua the audio source.

Of functions (1) and (2) it follows that HN is a symmetric function of the angle θ, and in a section perpendicular to the plane of the HN type (2) gives a circle. HN (2) forms in space geometry type "cone", i.e. is unidirectional, carving out space corner segment, the axis of which corresponds to the direction of maximum. Signal to the diver can come from any direction, including above or below, but the diver is supplied with the claimed device has the possibility is ity to identify the direction of a signal source with an accuracy up to the width of the "cone", not within the hemisphere, as suggested in the prototype.

Calculations show that in terms of real interference the accuracy of determining the direction to a signal source is 10-15° (half-width HN -3 dB). The diameter of the hydrophones in the frequency range, which are accepted for divers, 30-50 mm, weight with valve 100-200 g (in air).

Thus, the claimed technical effect consists in one direction finding the source of a sound signal coming from any direction, with acceptable for diving operations precision [1] and with the practical possibility of implementing at a complete set of diving equipment. Optionally, you can specify that when using only one phone for direction finding (and not the headphones with two phones on each ear to the second ear of the diver can be removed the phone from the other device, not the radio signal.

The invention can be used in underwater engineering, rescue, research, military issues, and to "bring" diver on the boat-the provider or to another object, for relative orientation when working in a group, in poor visibility conditions, under the ice.

Sources of information

1. Zanin V.Y., Malyshenko N.N., The Chebykin O.V. Equipment underwater swimmer. St. Petersburg: Izd-vo "Layout", 1997.

2. Pat With Whom And No. 2002109601. Scuba diver communication and tracking device (Simiona the diver communication system and device for navigation). IPC G08B 13/14. Publ. 15.08.2002 twelve.

3. The U.S. Pat No. 6272073. Underwater location and communication device (Device for underwater communication and orientation). IPC H04B 11/00. Publ. 07.08.2001.

4. Evidence of the Russian Federation for useful model №43370. Direction finder diver. IPC G01S 3/80. Publ. 16.01.2005.

5. Application No. 2002111457. Direction finder for the diver. IPC G01S 3/80. Publ. 10.11.2003 (PROTOTYPE).

6. Sarychev PPM, Dobrovolsky YU Hydroacoustic antenna. Leningrad: Sudostroenie, 1984.

1. Device for determination of a diver direction to the source of a sound signal containing two antennas, the path listening to the received signals, comprising serially connected first antenna amplifier with automatic gain control (AGC) and a headphone, and the tract provide a control voltage for the amplifier with AGC, characterized in that both antennas are made non-directional centers of the antennas are placed at a distance of a quarter wavelength of the carrier frequency of the received signal, the tract provide a control voltage for the amplifier with AGC consists of a unit delay time equal to a quarter period of the carrier frequency of the received signal, and adder, and the output of the second antenna is connected to the input of the delay device, the output of the first antenna connected to the signal input of the amplifier with the ROUX, connected also to the first input of the adder, the output of the delay device connected to the second input of the adder, the output of the adder is connected to the control input of the amplifier with AGC, the gain of the amplifier with AGC is inversely proportional to the level of the control signal.

2. The device according to claim 1, characterized in that the first antenna is located on the helmet of a diver on the line from the nose to the back side of the nose.

3. The method of determining the diver directions on the audio source (SFL), consisting of Desk diver level signal based on the reception signal SFL two spaced antennas and deciding on the direction of SFL, characterized in that the antenna is made undirected and spaced by a distance equal to a quarter wavelength of the carrier frequency of the received signal, while the output signal from the second antenna is delayed for a time equal to a quarter period of the carrier frequency of the received signal that is summed with the output signal from the first antenna, and for making decisions about the direction of SFL uses the signal received first antenna, and the level of this signal change is inversely proportional to the value of the level of the total signal change of the spatial position of the imaginary line connecting the centers of the antennas by changing the position of the diver in the space d is the maximum level recorded by the diver signal, and SFL is defined as the direction of the vector from the location point of the second antenna to the location of the first antenna.