Idrofoni

Gli idrofoni Brüel & Kjær sono trasduttori sonori calibrati individualmente. Ogni idrofono è caratterizzato da una risposta in frequenza piatta e sono omnidirezionali su un'ampia gamma di frequenze. Inoltre, la loro costruzione è assolutamente impermeabile, resistente alla corrosione e può resistere ad alti livelli di salinità. Se siete alla ricerca di un idrofono di qualità che funzioni a 1000 m di profondità, che possa resistere a pressioni statiche fino a 100 bar e che sia costruito per durare - vi trovate nel posto giusto.


HYDROPHONE SPECIFICATIONS

Brüel & Kjær hydrophones are piezoelectric transducers, designed to be used underwater for recording or listening to underwater sound.

The ceramic piezoelectric sensing element and its internal supporting structure are permanently bonded into sound-transparent, lead-free, nitrile butadiene rubber. Support structures are made from metal alloys that are extremely resistant to corrosion in virtually all hostile environments and have very good anti-fouling properties when immersed in seawater.

The internal support is mechanically and electrically isolated from the metal housing, being coupled only by synthetic rubber. This provides vibration isolation of the sensing element. 


RECEIVING SENSITIVITY

Each Brüel & Kjær hydrophone is submitted to an extensive aging and temperature stabilizing procedure before being individually calibrated. Individual calibration data and frequency response curves are supplied with each hydrophone.

The receiving sensitivity calibration of the hydrophones is traceable to international standards.


FREQUENCY RESPONSE

The frequency response of the four hydrophone types is shown here:

Frequency ResponseFrequency response measurements are made in a water tank in free-field conditions using a Brüel & Kjær PULSE™ calibration system. 


POLAR DIRECTIVITY

B&K Hydrophones deliver great omnidirectional sound measurements. The individual hydrophone directivity patterns in water, are shown here:

 

Hydrophone dispersion

The polar directivity patterns were measured in free-field conditions achieved using gating techniques in a water tank. This requires a standard hydrophone as a projector and the unknown hydrophone as the receiver.

HYDROPHONE COMPARISON





Type 8103



Type 8104



Type 8105



Type 8106

Sensitivity*

-211 dB re 1 V/μPa

+/- 2dB

-205 dB re 1 V/μPa

+/- 3 dB

-205 dB re 1 V/μPa

+/- 2 dB

-173 dB re 1 V/μPa

+/- 3 dB

Nominal Voltage Sensitivity

29 μV/Pa

56 μV/Pa

2.24 mV/Pa

Nominal Charge Sensitivity*

0.1 pC/Pa

0.44 pC/Pa

0.41 pC/Pa

N/A

Capacitance* (incl. standard cable)

3700 pF

7800 pF

7250 pF

N/A

Frequency Response* (re 250 Hz) Continuous is valid with integral cable

0.1 Hz to 20 kHz

+1/–1.5 dB

0.1 Hz to 10 kHz

+/-1.5 dB

0.1 Hz to 100 kHz

+1/-6.5 dB

10 Hz to 10 kHz

+0.5/-3.0 dB

Length up to:


0.1 Hz to 100 kHz

+1.5/-6.0 dB

0.1 Hz to 80 kHz

+/-4.0 dB

0.1 Hz to 160 kHz

+3.5/-10.0 dB

7 Hz to 30 kHz

+0.5/-6.0 dB

 

0.1 Hz to 180 kHz

+3.5/-12.5 dB

0.1 Hz to 120 kHz

+4/-12.0 dB

 

3 Hz to 80 kHz

+6/-10.0 dB

Horizontal Directivity 

(Radial, XY Plane)

+/- 2 dB at 100 kHz

+/- 2 dB at 20 kHz

Vertical Directivity

(axial, xz plane):

+/-4 dB at 100 kHz

+/-2 dB at 50 kHz

+/-2 dB over 270° at

80 kHz

+/-2.5 dB at 100 kHz

+/-3 dB at 20 kHz

Leakage Resistance* (at 20 °C)

>2500 MΩ

 


Operating Temperature Range
:

Short-term Continuous (-1 hr operation):

 


-30 to +120 °C
-30 to +80 °C

-10 to +60 °C

Sensitivity Change with temperature:

Charge Voltage:

 

0 to +0.03 dB/°C

0 to -0.03 dB/°C

 

0 to +0.03 dB/°C

0 to -0.04 dB/ °C

 

0 to +0.03 dB/°C

0 to -0.03 dB/°C

 

0 to +0.01 dB/°C

Max. Operating Static Pressure:

 
252 dB
= 4 x 106 Pa
= 40 atm
= 400 m ocean depth


260 dB

= 9.8 x 106Pa 
= 100 atm
= 1000 m depth

 

Sensitivity Change (Static Pressure):

0 to –3 × 10–7 dB/Pa
(0 to -0.03 dB/atm)

0 to 1 × 10–7 dB/Pa

0 to 0.01 dB/atm