Our 6G product family communicates with each other by the use of acoustic pulses of energy. These pulses travel through the water like a shock wave. Pulses sent and received by transceivers and transponders have to compete with external factors. For example, environmental factors such as varying water column conditions, physical placement of the transponder or working in noisy environments. 

To ensure the pulses get to the destination as cleanly as possible, locations of acoustic transponders should be chosen carefully. 

There are two main types of transponders that we use Sonardyne :

Directional transducers

This transducer is designed to direct the majority of its transmit energy and its receive sensitivity in the forward portion of the transducer. On a standard directional transducer, the metal ring at the end is where the acoustic energy dissipates. Ideal for when your target is operating in deep water or directly below your transceiver.

Omni-Directional transducers

This transducer type is designed to transmit its energy in more of a hemispherical pattern to ensure that maximum coverage is provided allowing for maximum robustness. The acoustic phase centre of this design is central to the rubber boot of the transducer. Ideal for ROV, AUV and diver tracking operating at high elevations or long slant ranges. 

With the above in mind, it is important to locate the transducer on the target in such a way as to ensure that there is both no shadowing of the transducer and no destructive interference caused by the reflection of acoustic signals. Think about line of sight, can the transceiver on your surface vessel see the transponder on the target you are tracking? Also, ensure your transponder isn’t mounted near any source of external noise or aeration. For example, avoid placement around ROV thrusters or divers expelled air.

For Omni-Directional transducers, the phase centre of the acoustic transducer should be located 50mm from any structure.

For Directional transducers, the phase centre of the acoustic transducer should be located 50mm from any structure.

The following are general mounting good practices to ensure optimum acoustic performance:

• Transponder mounts should have a 60-degree slope to help prevent reverberation from interfering with the acoustic signals.
• Transponders should be located away from vertical surfaces/obstructions.
• If the use of guard wire over a transducer is planned, then a diameter of <8mm should be used.
• If choosing to use a moulding over the transducer for protection/reduction then an acoustically transparent material should be used and tested to prove the lack of interference.