Based on the industry standard Gemini 720is platform, the Gemini 1200id employs a mechanical design that is tried and tested in the harshest of subsea environments and offers a degree of redundancy by design not afforded by any other commercially available platform. The sonar has been developed largely in response to requests from existing customers who regularly operate the Gemini 720is to depths as low as 4,000 m below sea level.
In addition to the 720 kHz acoustic frequency offered by the Gemini 720is, the Gemini 1200id introduces dual frequency operation with the addition of a new 1.2 MHz acoustic operating frequency which improves angular resolution from 1° to 0.6° and range resolution from 4 mm to 2.4 mm, resulting in a significant improvement in the final overall resolution.
A CUSTOM SOLUTION
The introduction of the 1.2 MHz acoustic operating frequency to the Gemini 1200id necessitated a redesign of the analog front-end electronics to handle the higher sampling rate requirements of the new higher-frequency mode of operation.
Rather than taking the easier and cheaper route of transitioning over to single-ended analog front-end integrated circuits developed for ultrasound applications as typically used by the majority of other multibeam sonars, the Gemini 1200id continues to employ an in-house developed analog front-end solution that incorporates fully differential receiver channels consisting of discrete low-noise amplifiers, discrete variable gain amplifiers, second-order bandpass filters, and discrete high-speed, high-resolution serial ADCs.
This custom analog front-end solution allows the receiver to be optimized for longer-range sonar applications rather than shorter-range medical ultrasound applications which primarily drive the development of ultrasound analog front-end integrated circuits due to the relatively larger volumes involved. As a result of its superior analog front-end tailored for sonar applications, the Gemini 1200id has a dynamic range twice as wide as its nearest competitor.
SHARPER IMAGING
The electronic circuits within the Gemini 1200id have also been optimized and where necessary additional filtering exclusively employed to minimize self-generated noise around the two acoustic operating frequencies resulting in significant reductions in unwanted artefacts that can appear in the sonar image. In addition to this, the Gemini 1200id actively attenuates external waterborne noise from other subsea equipment in the vicinity of the sonar, including from the likes of ROV thrusters which tend to generate relatively large levels of electromagnetic interference.
By pushing self-generated electrical noise away from the acoustic operating frequencies, and by actively attenuating external waterborne electromagnetic interference, the Gemini 1200id offers welcomed improvements in SNR.
The wide dynamic range and enhanced SNR of the Gemini 1200id enable it to produce sonar images displaying sharp and bright acoustic returns on a noise reduced dark background resulting in crisp sonar images of excellent clarity.
PRECISE CONTROL
A flight-time sensor operating at 1 MHz and integrated into the side of the Gemini 1200id measures the speed of sound in the water immediately around the sonar at the time of acoustic reception to ensure that observed targets are displayed accurately for position and size.
All auxiliary port features supported on the Gemini 720is are also supported by the Gemini 1200id, and the depth rating of 4,000 m is maintained, ensuring that the Gemini 1200id offers a direct upgrade path for customers who until now have been reluctant to consider anything beyond their trusted Gemini 720is sonars for mission-critical operations.
The Gemini 1200id can be controlled using either Genesis or software development kits that support integration into third party applications. Genesis is Tritech’s latest all-in-one software package for controlling, displaying and recording data from its portfolio of sensors. It boasts a modern, dynamic and easy to use interface with a comprehensive suite of integrated features.
To allow the Gemini 1200id to share bandwidth with other equipment and sensors that may be present on an existing or shared network connection, the data bandwidth consumed by the sonar can be limited by capping the ping rate, reducing resolution, or enabling data compression.
SONAR SUPPORT
Every Gemini 1200id sonar that rolls off the production line is subjected to a strict factory acceptance testing regime to guarantee quality and performance. As part of this testing, every function of the sonar is verified and additional tests at pressure limits conducted to confirm operation under extreme conditions. The design of the sonar is qualified to ensure reliability against shock and vibration, corrosion, and for compliance against relevant EMC regulations.
All purchases of the Gemini 1200id are available with an extended warranty of three years. Although the Gemini 1200id is based on a proven and reliable platform, extended warranty provides customers with peace of mind so that they can concentrate on conducting their mission-critical operations under the certainty that the Tritech support network is available to offer advice and support 24/7, 365 days a year.
This feature appeared in ON&T Magazine’s 2025 October Edition, Subsea Infrastructure: Integrity & Security, to read more access the magazine here.
