Directional Acoustic Transducers (Echo Sounders) Posted by Business Development Manager March 8th, 2018

Directional Acoustic Transducers (Echo Sounders)

Sensor Technology Ltd. has designed and manufactured a large number of directional acoustic transducers, with frequencies ranging from 18 kHz up to 3 MHz. Common uses include acoustic telemetry, pinger & transponder networks, navigation systems, underwater positioning, hydrographic survey and fish finding. Ultrasonic echo sounder-type transducers are also increasingly common in non-marine environments. The proximity sensors and fluid level sensors commonly found on automated production lines are often an echo sounder style of design. Similarly, many systems for measuring gas flow and fluid flow rates depend on directional transducers. Echo sounder transducers can be used in either send & receive (echo sounding) or send-only modes, as dictated by the application.

SX34-18
18 kHz low frequency echo sounder (SX34-18)

Technical Specification

RESONANCE FREQUENCY
18 kHz

BEAM ANGLE AXIAL 3DB AT FR
14° (Conical)

DEPTH RATING
1500 m

TRANSMIT VOLTAGE RESPONSE TVR
165 dB re 1 µPa/V @ 1m

SX08-02
50 kHz 200 kHz dual frequency echo sounder (SX08-02)

Technical Specification

RESONANCE FREQUENCY
50 & 200 kHz

BEAM ANGLE AXIAL 3DB AT FR
48° (@ 50 kHz) & 12° (@ 200 kHz)

DEPTH RATING
100 m

TRANSMIT VOLTAGE RESPONSE TVR
145 (@ 50 kHz) & 165 (@ 200 kHz) dB re 1 µPa/V @ 1m

SX20-02
200 kHz ultrasonic echo sounder (SX20-02)

Technical Specification

RESONANCE FREQUENCY
200 kHz

BEAM ANGLE AXIAL 3DB AT FR
20° (Conical)

DEPTH RATING
100 m

TRANSMIT VOLTAGE RESPONSE TVR
140 dB re 1 µPa/V @ 1m

echo sounder vertical resolution is determined by frequency

Directional Acoustic Transducers: Vertical Resolution

Echo sounding uses the timing of a returning echo to determine the distance to a target. Targets positioned closer together than one wavelength will create echoes that the system perceives as a single return, and the system will identify it a single target. A shorter wavelength improves the vertical resolution. However, given that the wavelength is a function of frequency, it is in fact the operating frequency of a directional acoustic transducer that determines vertical resolution.

echo sounder horizontal resolution is determined by beam width

Directional Acoustic Transducers: Horizontal Resolution

Similarly, if multiple objects produce multiple echoes that all return to the transducer at the same time, the system will perceive a single return. The system will identify the result as a single target. A narrow beam can be used to reduce the potential for multiple returns. So, the directionality (i.e. beam width) of an echo sounder determines horizontal resolution.

Customizing Directional Acoustic Transducers

The operating frequency and beam angle are both customizable, which is why directional acoustic transducers are so versatile. We can modify a number of design parameters to meet the exact performance specifications of your application. Design variables that can be adjusted to meet your requirements include:

  • operating frequency,
  • beam angle,
  • bandwidth,
  • operating depth, and
  • packaging (e.g. housing, mounting points, cable/connector type).

The possibilities are virtually endless. Contact us to discuss your requirements.