Tritech Gemini NBI – Narrow Beam Imaging

The Gemini NBI offers a narrow vertical beam and 130° swath.


The Gemini NBI produces an acoustic image, cutting through the water with a narrow acoustic beam and at the high refresh rate users can expect from the Gemini range of multibeam sonars.
Based on the proven design of the Gemini 720i, the Gemini NBI uses a 1° vertical beam instead of the 20° vertical beam found on the 720i. This reduced beam width allows the user to more precisely identify the position of the acoustic targets than is possible with a wide beam imaging sonar which is commonly used for obstacle avoidance operations.
Operating at 620kHz the Gemini NBI is able to produce images with 10mm range resolution while the 0.5° horizontal angular resolution results in an extremely sharp sonar image. Where monitoring your position relative to a known target is the objective and not general obstacle avoidance, then the Gemini NBI can help guide you safely to the desired target.
The multibeam transducer design used for the Gemini NBI results in a 130° sector scan width and advanced technology allows update rates as high as 30 scans per second. With wide angle imaging and a high refresh rate the user is able to quickly and effectively manoeuvre to a target in poor visibility conditions.
Depth rated to 4000m and manufactured from titanium the Gemini NBI has been designed to work in the harshest of environments such as those typically found in subsea mining and excavation.

The Tritech Seanet Pro software package supports the Gemini NBI enabling the network of other Tritech sensors. A standalone Gemini software package is also available which offers users a tailored control and display interface including a click and track function and engineering measurement tools. Gemini software also has typical features common with Seanet Pro such as data recording/ playback, screen capture, range and gain control, colour palette selection, cursor reporting. A software development kit is available for autonomous vehicle operations.

Interface Options
For information on various interface options for this product, please see the following link to the interface options datasheet.

Technical information

Acoustic Specifications
Operating Frequency: 620kHz
Angular Resolution: 1.0° acoustic, 0.5° effective
Swathe: 130°
Number of Beams: 256
Vertical Beamwidth: 1°
Range: 0.5 to 120m
Update Rate: 5 – 30Hz (range dependent)
Range Resolution: 10mm (range dependent)
Pulse Length: 25 – 200μs (range dependent)

Power Consumption: 37W maximum (range dependent, head unit only)
Supply Voltage: 22 – 75V DC
Communications Protocols: Ethernet (up to 80m) or VDSL (up to 1000m)
Connector Type: Burton 5506 Series
VDSL cable length: Maximum length for VDSL and power is 300m, if power is provided locally
(e.g., by the ROV), then cable length for VDSL communications is 1000m.

Physical Specifications
Weight: 14.6kg air, 9.5kg water
Depth Rating: 4000m
Material: Titanium (6 AL-4V)
Finish: Bead blasted
Operating Temperature: -10 to 35°C
Storage Temperature: -20 to 50°C