FAQ (Frequently Asked Questions) Bellow is a list of Frequently Asked Questions. If you don’t find any FAQs covering your questions, please use the contact form to e-mail the question to RESON. We will try to answer you as soon as possible.
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Can hydrophones operate under full vacuum?
Yes. Many RESON models have been used in water tunnels under vacuum conditions Read more
Why is the base material of RESON hydrophones chosen to be Sea Bronze instead of Stainless steel?
"Sea Bronze"; or Aluminum Bronze Alloy (ALCu10Ni5Fe4) has shown to have a better corrosion resistanc Read moree over time than Stainless Steel. Sea Bronze material has over the years demonstrated very-very good corrosion resistance. To have absolutely best corrosion results, then never clamp directly on the sea bronze housing using other metals. Instead use electrical isolating mounting brackets to avoid any electro galvanic corrosion. Keep minimum of a few millimeters clearance from metal parts to sea bronze housing.
Why does plots for hydrophones only show measurements from 5kHz and upwards?
As a standard RESON does not calibrate hydrophones in water below 5kHz, due to the limitations in si Read moreze of our test tank. Measurements at lower frequencies will require, that measurements needs to be performed in open sea, which is very expensive.
Instead receive sensitivity measurements are performed in air at 250Hz using calibrated pistonphone and pistonphone coupler, and this value is compared to measurement at 5kHz.
Many years of experience have shown that hydrophone sensitivity has a very flat response up to 5kHz, therefore measurements at these frequencies are not worth performing.
Why has special formulated NBR replaced Chloroprene rubber as encapsulation material in Reson hydrophones?
A small amount of lead added to the chloroprene vulcanized rubber used in RESON hydrophones ensured Read morethe acoustic properties, long lifetime, sturdiness in hostile environments and other properties of the compound and RESON hydrophones.
RESON anticipated regulations in the use of lead and initiated comprehensive testing of a broad range of alternatives 10 years ago. The tests included such properties as water permeability, quelling, acoustic properties, electrical properties, abrasion resistance, tensile strength and long-term stability in various environments.
The NBR rubber demonstrated equal performance, and therefore replaces chloroprene for the RESON 1000 and 4000 series transducers and hydrophones without any change in performance specifications and physical outlines.
Additionally the NBR rubber encapsulation has very good chemical resistance to hydrocarbons and other pollutants likely to be found in harbors. It is also well suited for applications directly submerged in fluids such as kerosene and castor oil.
However NBR show some sensitivity to UV and Ozone, and care should therefore be taken not to expose the hydrophones to direct sunlight and weathering for very long periods.
What is the difference between input and output gain for CCA1000?
The input gain is capacitive gain (or attenuation) by adjusting the input capacitance in relation to Read more the hydrophone and cable. The Output gain is a voltage gain from a standard voltage preamplifier (resistors). The 2 values combined give the total gain of the signal going through the CCA1000.
What is the maximum Sound pressure level I can measure with TC4035 or TC4038?
+227dB re 1µPa/V (0.2MPa) can be measured with the TC4035 before the preamplifier saturates +235 Read moredB re 1µPa/V (0.6MPa) can be safely measured with the TC4038
What sensitivity loss can be accounted for by pressure?
Approx. 0.03dB/Bar (1bar=10m) Read more
What does dB sensitivity means?
Decibel (dB) is a comparative reference unit, 1Volt output per µPa at 1m distance (dB re 1V/µPa) Read morer>The more negative the number, the more sensitive the hydrophone; TC 4032 is –170 dB re 1V/Pa is more sensitive than TC 4013 -211dB re 1V/Pa
What it translates to is +211dB sound pressure level (SPL) will result in 1Vrms output from the hydrophone. An increase or decrease in SPL will result in a corresponding increase or decrease in Voltage output. Every 6dB change is SPL = doubling or halving the voltage output: Ex) TC 4013 (Sensitivity or Open Circuit Voltage (OCV) is -211dB re 1V/Pa) +193dB results in 0.125Vrms output +199dB results in 0.25Vrms output +205dB results in 0.5Vrms output +211dB results in 1Vrms output +217dB results in 2Vrms output +226dB results in 4Vrms output +232dB results in 8Vrms output Use equation SPL = 20log(Vrms) - OCV
How do I determine signal pressure level (SPL), or energy level from a source, at the tip of a hydrophone? (In dB, and then convert to Pascal?) All this based on the output reading on my oscilloscope.
Formula 1) SPL = 20log(Vrms) – OCV RL = 20log(Vrms) – OCV (RL and SPL are the same, the Read more sound pressure level at the hydrophone tip is the receive level) RL = receive level at phone (this is the unknown here) OCV = hydrophone sensitivity (-211dB re uPa/V for TC 4013)
Formula 2) Vrms = Vpp/2sqrt2 or Vp/sqrt2 Oscilloscopes readings usually give you Vpp Signal Analyzers may give you dBVrms
Formula 3) dBV = 20log(Vrms) Ex) If you get 1V output from your TC 4013 hydrophone using an oscilloscope (Hyd sensitivity is -211dB): Vrms=Vpp/2sqrt2 = 1Vpp/2sqrt2 = 0.353Vrms dBV - OCV = SPL 20log(Vrms) - OCV = SPL 20log(0.353) - (-211) = 202dB So energy level at the hydrophone is 202dB re 1V/Pa
How many Pa is 202dB?
Formula 4) 20log(uPa) = dB uPa = 10E(dB/20) = 10E(202/20) = 10E(10.1) = 1.2589 E10 uPa = 12589 Pa
What is the maximum voltage I can use to drive the TC 4013, TC 4033, TC 4034 as projectors?
100Vrms max @ 1% Duty Cycle 10Vrms max @ 10% Duty Cycle 1Vrms max @ 100% Duty Cycle
Eac Read moreh decade increase of input voltage = 20 dB addition signal output Formula: 20logV = SPL V = voltage input SPL = pressure level in dB added to transmit sensitivity at given frequency EX) TC 4013 transmitting at 40kHz; refer to the included 'Transmit Sensitivity' plot at 40kHz 1Vrms = 110dB re 1uPa/V at 1m 10Vrms = 130dB 100Vrms = 150dB
What are the example of using 2 x TC 4013, one as a projector, one as a hydrophone?
TC 4013 can be used as a transmitter. Any signal/function generator can be used for low power. A Po Read morewer amplifier may be required for more power.
One-Way Transmission Loss formula: RL = SL - 20logR - R RL = receive level at hydrophone SL = source level at transmitter R = range (m) = attenuation coefficient (based on temperature, frequency, salinity)
Example) Using 2 x TC 4013, one to transmit, one to receive
