Many Sonardyne transponders, like members of the Fetch family, have configurable power and linear gain settings. These are important values because they determine how much sound the instrument will make when transmitting and how hard it will listen when receiving. These parameters sometimes need adjusting to optimise the acoustic link reliability for the subsea environment being operated in (depth, background noise etc). But what about when testing the acoustic link in-air before deployment?

When running pre-deployment tests and checks on a Fetch instrument with configurable power and gain settings, low power and gain settings should be applied. Low power is needed because the output power needed for underwater transmission would be excessive when in-air, and low gain since gain controls the sensitivity of the receiver and you want to avoid sensor saturation when in-air.

Power and linear gain of a Fetch instrument can be viewed using the iWand and to configure these parameters, use applicable Sonardyne software such as the iWand 6G Configurator software, 6G Terminal Lite or Subsea Array Manager (SAM).

When conducting pre-deployment testing for LMF Fetch units, it is absolutely critical to use in-air acoustic settings for reliable acoustic communications. These in-air settings will mean that power and gain are optimised and more favourable for in-air conditions whilst lowering the receive wait time.

Remember, if the power and gain of your Fetch were set for ‘in-air’ use for testing and setup purposes, it is imperative these settings are changed once the unit is submerged to be optimised for the ‘at-depth’ operating range. This can be done via SAM, and remember to click ‘Update job’ to save the new settings.

When your Fetch is subsea and you’re ready to start using the acoustic link, ensure the power and gain settings of both the Fetch and the topside transceiver are configured appropriately to optimise the link.

You can find out more detail on how to set up and deploy a Fetch instrument by watching the videos below or by checking out other Fetch-based FAQs.