A PRESSURE COUPLING CHAMBER FOR HYDROPHONE CALIBRATION

Abstract

The present invention is a pressure coupling chamber (1) developed for comparison calibrations of acoustic pressure-sensitive hydrophone (2) in the frequency range from Hz to 1 kHz. A hydrophone (2), reference receiver unit (3) and acoustic source (6) under test are acoustically coupled in the chamber through the air-filled medium inside the pressure coupling chamber (1). Acoustic sources (6) that are going to create acoustic pressure in the pressure coupling chamber (1), placed on the side walls of the chamber (1) to surround the pressure-sensitive active surface of hydrophone (2), are driven to create a hydrostatic pressure effect in the related frequency range in the chamber. Calibration of tested hydrophone (2) with comparison method is carried out by measuring the output voltages of tested hydrophone (2) and the reference receiver unit (3).

Claims

1) A pressure coupling chamber (1) for comparison calibration of hydrophone, comprising At least one hydrophone (2), At least one hydrophone adapter (9) intertwined with the hydrophone (2), Suitable fastener for providing sealing between the hydrophone and the hydrophone adapter (14), At least one thread adapter (7) located at the top of the hydrophone adapter (9), Suitable fastener for sealing (13) to provide sealing between the hydrophone adapter (9) and the thread adapter (7). Suitable fastener for fixing (8) the thread adapter (7) to the hydrophone adapter (9). Pressure coupling chamber body (4) located between the thread adapter (7) and the reference receiver unit sealing tube (5), Internal volume of the pressure coupling chamber (A) formed between the pressure coupling chamber body (4) and the hydrophone, At least two acoustic sources (6), located and evenly spaced around the pressure-sensitive active surface of the hydrophone element and mounted to the pressure coupling chamber body (4) symmetrically, At least one thread pin (11) and an acoustic cap (10) in the pressure coupling chamber body (4), and fixed with the suitable fasteners (15) for fixing to the acoustic cap (10), Laboratory standard microphones (LS1 or LS2) as a reference receiver unit (3), At least one reference receiver unit (3) fixed to the upper part of the hydrophone (2) with fasteners suitable for sealing (12) and sealed with the sealing tube (5), Air medium in the internal volume of pressure coupling chamber (A), which is not subjected to a separate pressurization externally.

2) A pressure coupling chamber (1) according to claim 1, characterized in that the reference receiver unit (3) placed coaxially relatively pressure coupling chamber body (4) and the hydrophone (2).

3) (canceled)

4) A pressure coupling chamber (1) according to claim 1, characterized in that the acoustic sources (6) are placed in the pressure coupling chamber body (4) equidistantly and symmetrically around the hydrophone, and driven in the same phase.

5) (canceled)

6) A pressure coupling chamber (1) according to claim 1, characterized in that the Laboratory Standard microphone is used as the reference receiver unit (3).

Description

DESCRIPTION OF THE FIGURES

[0039] FIG. 1: Perspective drawing of the schematic image of the product that is the subject matter of the invention.

[0040] FIG. 2: Sectional drawing of the schematic image of the product that is the subject matter of the invention.

DESCRIPTION OF THE REFERENCES IN THE FIGURES

[0041] 1. Pressure coupling chamber [0042] 2. Hydrophone [0043] 3. Reference receiver unit [0044] 4. Pressure coupling chamber body [0045] 5. Reference receiver unit sealing tube [0046] 6. Acoustic source [0047] 7. Thread adapter [0048] 8. Fastener for fixing thread adapter [0049] 9. Hydrophone adapter [0050] 10. Acoustic cap [0051] 11. Thread pin [0052] 12. Fastener for sealing the reference receiver unit [0053] 13. Fastener for sealing the thread adapter [0054] 14. Fastener for sealing the hydrophone [0055] 15. Fastener connecting the hydrophone adapter to the thread adapter [0056] A Internal medium of the pressure coupling chamber

DESCRIPTION OF THE INVENTION

[0057] In the pressure coupling chamber, that is the subject of the invention, the hydrophone (2) which is desired to be calibrated and the reference receiver unit (3) to be used during the comparison method are exposed to the same conditions in the pressure coupling chamber (1).

[0058] The acoustic pressure generated by acoustic sources (6) in the pressure coupling chamber (1) is determined by measuring with the reference receiver unit (3) and the value obtained is compared by the conversion of the voltage value, which is the output of the hydrophone (2) exposed to the same pressure, into acoustic pressure.

[0059] Hydrophone under calibration (2) and the reference receiver unit used as reference pressure sensor (3), mounted on the pressure coupling chamber body (4) with the loudspeaker cap (10), thread pin (11) and fastener suitable for fixing (15), are exposed to the acoustic pressure generated preferably by at least 2 pieces of acoustic sources (6) depending on the dimensions of the pressure coupling chamber. Acoustic sources (6), placed preferably equidistance to face each other in the direction of the hydrophone (2) axis, are mounted to the pressure coupling chamber body (4) symmetrically. The hydrophone (2), which is placed in the pressure coupling chamber with the hydrophone adapter (9), is fixed by the thread adapter (7) and the fastener (8) suitable for fixing. Sealing is ensured between the parts that compose the pressure coupling chamber (1) by the suitable fasteners (12,13,14) for sealing. In order to expose the reference receiver unit (3) to the acoustic pressure generated in the pressure coupling chamber (1), the reference receiver unit (3) is mounted to the pressure coupling chamber body (4) with the reference receiver unit sealing tube (5).

HOW THE INVENTION IS APPLIED TO THE INDUSTRY

[0060] The present invention is designed for performing calibrations of electro-acoustic transducers used in the field of underwater acoustics (hydrophones (2)) in the frequency band from a few Hz up to 1000 Hz. While calibrations of such elements at frequencies 1000 Hz and higher are performed in test tanks, the acoustic wavelengths at lower frequencies approach the dimensions of the test tank so that the surface reflections of the test tank affect the measurement conditions. With the calibration structures expressed as the pressure coupling chamber (1), the upper frequency limit for hydrophone calibration can be increased from the state-of-the-art 350-400 Hz range to the level of 1000 Hz. The calibration device (1), which is the subject of the invention, can be transferred to the industry for the needs of primary and secondary calibration laboratories and research institutions working in this field.

[0061] *The Project Leading to this application has received funding from the EMPIR Programme co-financed by the Participating States and from the European Union's Horizon 2020 Research and innovation Programme