RU2105955C1 - Fiber-optical meter of vertical distribution of velocity of sound in ocean - Google Patents

Abstract

FIELD: underwater acoustics, determination of dependence of velocity of sound on depth of ocean. SUBSTANCE: meter incorporates fiber-optical coils attached to rod-towline at equal distances, source 3 of coherent light, photodetector 4 optically coupled with interferometer, phase shifter 5, projector and unit 9 for processing and recording. EFFECT: improved operational characteristics. 3 cl, 5 dwg

Description

 The invention relates to the field of hydroacoustics and can be used to determine the dependence of the speed of sound on the coordinate, for example, by the depth of the ocean.

Known meter of the same purpose, containing vertically mounted pulsed sonar emitter and several reflectors of sound, as well as blocks of processing and recording equipment [1]
A disadvantage of the known meter is the lack of an optical signal at its output, which makes it difficult to coordinate with the optical communication line, which in the near future will be the main channel for transmitting information.

A known meter of the vertical distribution of the speed of sound in the ocean, containing control elements fixed to a tugboat at a fixed distance from each other, a pulsed sonar emitter mounted at one end of the tugboat, opposite the control elements, processing and recording unit [2]
This meter is taken as a prototype.

 The disadvantage of the prototype is the absence of an optical signal at the output of the meter.

 The technical result obtained by the implementation of the invention is the provision at the output of the meter of the vertical distribution of the speed of sound of an optical signal that carries information about the measured velocity field.

 This technical result is obtained due to the fact that in the known meter of the vertical distribution of the speed of sound in the ocean, containing control elements fixed to the tow bar at a fixed distance from each other, a pulsed sonar emitter mounted at one end of the tow bar, opposite the control elements , a processing and registration unit, a coherent light source and a photodetector are introduced, the output of which is connected to the input of the processing and registration unit, and the control elements are made s in the form of sensitive fiber coils formed by the supporting and subject fibers located along the length of the tow bar, the coherent light source, photodetector, reference fiber and subject fiber being optically matched to the interferometer via a fiber communication line.

 At the same time, a phase-shifting device is installed in the subject or reference optical fiber.

 A pulsed sonar emitter is connected to a pulse-width signal generator, and the processing and recording unit includes a band-pass filter, the input of which is the input of this unit.

 Figure 1 presents the structural diagram of the meter; figure 2 is an optical diagram of the meter; in FIG. 3-5 time diagrams explaining the principle of operation of the meter.

 The meter contains (Fig. 1) fixed on the tow bar 1 at a known distance from each other control elements in the form of fiber optic coils 2, a source of coherent light 3 and a photodetector 4, optically matched to the interferometer (figure 2).

Fiber coils 2 in the interferometer are located in its supporting and subject shoulders (fibers) and are sensitive elements made in the form of separate parts of the subject and reference fibers. All fiber coils 2 are located in the medium under study, therefore, their division into subject and support is conditional (in figure 2, the subject coils are conventionally designated under the position 2 ₁ , and the support under the position 2 ₂ .

 In the subject or reference optical fibers installed phase-shifting device 5.

 Opposite the sensing elements mounted pulsed sonar emitter 6.

 In the particular case of a pulsed sonar emitter 6 can be connected to a pulse width generator (not shown) and emit pulse width signals. In this case, a band-pass filter 7 is installed at the output of the photodetector 4, the output of which through an amplifier 8 is connected to the block of recording equipment 9. Blocks 7, 8, 9 form a structurally processing and registration block.

 All processing and recording equipment, as well as electric signal generators, are, for example, in a floating buoy 10, also equipped with a radio transmitter (not shown) and a radio antenna 11.

 Electronic equipment may be located on a ship or other craft. The meter is also equipped with all the necessary tools for immersion and lifting (not shown in the drawing).

 The meter works as follows.

 The meter is lowered into the studied region of the ocean and all the elements of the equipment located in the embodiment of the meter shown in Fig. 1 are included in a buoy 10 floating on the surface of the ocean.

Turning on the equipment can be done remotely through the radio antenna 11 or according to a predetermined program. In this case, the initial phase difference on the output curve 12 of the interferometer (Fig. 3) is pre-set, for example, using the phase-shifting device 5 (Fig. 2) equal to 90 ^o (in Fig. 3, point A).

 Pulse sonar emitter 6 (figure 1) emits on the control elements in the form of fiber coils 2 acoustic pulses. In this case, at the output of the interferometer, a series of 13 photocurrent pulses will be observed (Fig. 4), which carries information about the speed of sound at various depths of the ocean.

 To improve the noise immunity of the meter to various hydroacoustic interferences, the pulses emitted by the hydroacoustic emitter can have a pulse-width character, i.e. represent segments of sinusoids 14, following at certain intervals of time (figure 5).

 In this case, at the output of the meter (photodetector 4) there will also be a series of photocurrent pulses that are emitted against the background of interference by a band-pass filter 7, amplified by an amplifier 8, and recorded by a recorder 9 (Fig. 2).

 The amplitudes of the emitted pulses are set based on the dimensions of the linear portion of the output curve 12 (in Fig. 3, under the position 15 the input signal of the interferometer is indicated, and under the position 16 its output signal).

 Thus, the meter allows you to measure the vertical distribution of the speed of sound in the ocean using a single fiber-optic interferometer. At the same time, its useful signal in the form of optical pulses will not be affected by stationary interference (temperature, hydrostatic pressure), since both support and object coils are located in the same medium.

Claims (3)

 1. A meter for the vertical distribution of sound velocity in the ocean, comprising control elements fixed to a tug-rod at a fixed distance from each other, a pulsed sonar emitter mounted at one end of the tug-rod opposite the control elements, a processing and recording unit, characterized in that a coherent light source and a photodetector are introduced into it, the output of which is connected to the input of the processing and recording unit, and the control elements are made in the form of sensitive fiber optic optical coils formed by the supporting and subject optical fibers located along the length of the tow bar, the coherent light source, the photodetector, the reference fiber and the subject fiber being optically matched to the interferometer via an optical fiber communication line.  2. The meter according to claim 1, characterized in that a phase-shifting device is installed in the subject or reference optical fiber.  3. The meter according to claim 1, characterized in that the pulsed sonar emitter is connected to a pulse-width signal generator, and the processing and registration unit includes a band-pass filter, the input of which is the input of this unit.

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