In Deep

Ryan Dixon says an advantage for NovAtel when creating a GNSS +INS solution from one of its GNSS boards is that the company's engineers understand, in the minutest detail, how those GNSS boards function. “We have access to every bit of information, and what this allows us to do is create a much more robust solution in all respects.” both worked for the same company. When Mutschler left that company to found Seahorse, and Eriksen went to work for Norbit, the two continued to collaborate. Between them they offer over 35 years of industry experience.

Today, Seahorse Geomatics is the NovAtel marine SPAN dealer worldwide. They are also the North American dealer for NORBIT and a key partner providing services world wide. Much of the initial phase evaluation and testing of the new Norbit sonar system was carried out by Mike Mutschler and his team at Seahorse.

Mutschler explains: “Seahorse Geomatics was contacted by Norbit in 2012 to provide a practical bathymetric surveying context for the development of their all-new curved-array multibeam sonar system.”

Since 1998, he says, Seahorse has been involved in the marine surveying sector, providing seismic surveying, offshore positioning, dredging, coastal engineering, geological sciences, acoustic sensor manufacturing and services in hydrographic disciplines. “This put us in a good position to help Norbit sonar developers to better understand the challenges associated with bathymetric mapping and therefore direct R&D efforts towards solving or simplifying these from the ground-up,” Mutschler says.

“The resulting Norbit iWBMSc is a tightly integrated, wide-swath multibeam sonar kit with co-located attitude and coupled GNSS/INS solutions in a small form factor. The critical requirement to meet or exceed strict specifications, as published by the International Hydrographic Organization, US Army Corps of Engineers, Rijkswaterstaat, etc., is maintained.”

Seahorse Geomatics and Norbit are linked, Mutschler says, “in a boundary-free synergistic working relationship that combines discrete passions for acoustics pioneering and increasing bathymetric mapping efficiencies.” The result is the most compact high-performance sonar available, a revolutionary bottommapping solution capable of delivering waterdata products of the highest quality.

In addition to providing key technical input, says Eriksen, “Mike is our go-to-market partner. He does our system testing and client contact. He represents our products at trade shows and performs demonstrations.”

A Truly Groundbreaking System

Mutschler says the Norbit iWBMSc system is broadband-enabled, allowing up to 80 kHz FM pulses centered at 400 kHz, and incorporates a curved receiver array of multiple piezoceramic elements. “This allows for narrow beams to be maintained across a wider angular swath width than typical planar/flat receiver arrays.” This results in smaller beam footprints on the bottom surface for increased data resolution and accuracy.

Multibeam sonar systems are most often mounted on floating or submerged survey vessels that are heading, pitching, rolling, heaving in different directions, with varying dynamics at play on or under water surfaces. The Norbit multibeam sonar measures several hundred beams, each having a unique two-way travel time and across-track pointing angle from nadir which must be combined with accurate survey platform positioning, attitude-roll, pitch and heading and sound speed to derive a final and repeatable XYZ location on a common projection.

“When the different sensors are separated, vertical and horizontal uncertainties are increased due to offset measurement errors, sensor misalignments and platform flexing,” Mutschler explains. To solve this, Norbit puts the NovAtel GNSS +INS deep within the sonar hardware.

“The STIM300 IMU is situated directly inside the already compact sonar head,” says Mutschler. “The benefits include fixed and very small lever arm offsets which effectively eliminate sensor-to-sensor flexing, simple setup and integration with a single LAN cable for complete data acquisition on a laptop, and a compact size for simple mounting on nearly any sized platform, from a sea kayak to a large survey ship.”

NovAtel's Ryan Dixon states: “The big deal here is that we are getting a level of correction in relation to price not available in the past. Because of the integration there is less possibility of error.”